About
Care Guide
More About How-Tos
Pests & Diseases
More Info
Related Articles
Add to My Garden Chinese peony 'Jan van Leeuwen'
Paeonia lactiflora 'Jan van Leeuwen'
Also known as : Fragrant peony 'Jan van Leeuwen'
Chinese peony 'Jan van Leeuwen' delights the eye with bowl-shaped satin-white flowers with yellow centers that bloom from late spring to early summer. Foliage is dark green and dense. This is a cultivar of Chinese peony, named after the originator Jan van Leeuwen in 1928. This lovely cultivar is sought after and treasured by peony enthusiasts.
Hardiness Zones
5 to 8
Care Guide for Chinese peony 'Jan van Leeuwen'
Average water needs, watering when the top 3 cm of soil has dried out.
Chalky, Sand, Acidic, Neutral, Alkaline
Full sun, Partial sun
5 to 8
Know the light your plants really get.
Find the best spots for them to optimize their health, simply using your phone.
Scan QR code to download
Chinese peony 'Jan van Leeuwen'
Sunlight
Full sun
Download and print this plant care card and attach it to your plants
Download
Chinese peony 'Jan van Leeuwen'
Sunlight
Full sun
Download
Chinese peony 'Jan van Leeuwen'
Sunlight
Full sun
Download
More About How-Tos
Lighting
Full sun
Temperature
-20 35 ℃
Common Pests & Diseases
Common issues for Chinese peony 'Jan van Leeuwen' based on 10 million real cases
Brown spot
This infection can cause brown spots or patches to appear on the plant.
Solutions: In minor cases of brown spot, there isn’t any need to treat the disease. However, if much of the foliage is affected and defoliation occurs, the plant will benefit from getting rid of the infection. It is recommended to start by applying organic treatment options, working up to the more potent synthetic, chemical fungicides if necessary. Organic options won’t kill the fungus, but will prevent it from spreading. Dissolve ½ teaspoon of baking soda and one teaspoon of liquid soap in a gallon of water. Using a spray bottle, spray on tops and bottoms of leaves until the mixture drips off. Repeat every two weeks until existing spots stop enlarging and new spots no longer appear. Spray a copper-based fungicidal soap on the leaves, coating the top and bottom leaf surfaces. Reapply as directed on the product label. Copper penetrates the leaf surface and prevents germination of spores so the fungus cannot spread. Apply an all-purpose fungicide to the entire plant, following the label instructions carefully.
Petal blight
Bacterial infections can cause flowers to become soft and rotten.
Solutions: Like other fungal diseases, the progression of petal blight is extremely difficult to stop and impossible to reverse once it infects a plant. The best course of action is to remove all damaged flowers immediately and dispose of them entirely. Do not put them in the compost pile, where spores could grow and spread.
Caterpillars
Caterpillars are fleshy moth or butterfly larvae that come in an array of colors, patterns, and even hairstyles. They chew on leaves and flower petals, creating large, irregular holes.
Solutions: Even though caterpillars are diverse, they all chew on plant parts and can cause significant damage if present in large numbers. For severe cases: Apply insecticide. For an organic solution, spray plants with a Bacillus thuringiensis (Bt), which specifically affects the larval stage of moths and butterflies. Be sure to coat plants, since caterpillars need to ingest Bt for it to be effective. This will not harm other insects. Spray a chili extract. Chili seeds can be cooked in water to make a spicy spray that caterpillars don't like. Spray this mixture on the plants, but be aware it will also be spicy to humans. Introduce beneficial insects. Release beneficial insects to the garden that eat caterpillars, such as parasitic wasps. For less severe cases: Hand pick. Using gloves, pick off caterpillars on plants and dispose of them in a bucket of soapy water. Dust plants with diatomaceous earth. This powder is harmless to humans but irritates caterpillars. Therefore, it will make it difficult for caterpillars to move and eat.
Underwatering
Leaves may wilt for a variety of reasons.
Solutions: The easiest (and most obvious) way to address underwatering is to fully hydrate the plant. However, this must be done carefully. A common mistake that many gardeners make is to douse their underwatered plants with water. This can overwhelm the roots of the plant and shock its system, something that can be even more damaging than the lack of water to begin with. Instead, water thoroughly and slowly, taking breaks to let the water slowly saturate through the soil to get to the roots. Use room temperature water, as cold water might be too much of a shock. In the future, shorten the time between waterings. A good rule of thumb is to check the soil around each plant daily. If it’s dry to at least two inches down, it’s time to water. If a container plant is repeatedly drying out very quickly, repotting into a slower-draining container might be a good idea, too.
Treat and prevent plant diseases.
AI-powered plant doctor helps you diagnose plant problems in seconds.
Brown spot
This infection can cause brown spots or patches to appear on the plant.
Overview
Discolored spots on the foliage of plants are one of the most common disease problems people observe. These spots are caused by fungal and bacterial diseases, with most infections related to a fungal pathogen.
Brown spot can occurs on all houseplants, flowering ornamentals, vegetable plants, and leaves of trees, bushes, and shrubs. No plants are resistant to it, and the problem is worse in warm, wet environments. It can occur at any point in the life stage as long as leaves are present.
Small brownish spots appear on the foliage and enlarge as the disease progresses. In severe cases, the plant or tree is weakened when the lesions interrupt photosynthesis or cause defoliation.
Symptom Analysis
In most cases, brown spot only affects a small percentage of the whole plant, appearing on a small amount of the leaves. A small infection only puts minor stress on the plant. However, if left untreated and the disease progresses over numerous seasons, it will severely impact the health and productivity of the infected specimen.
- Sporulation begins (reproduction of the fungal spores), and tiny spots appear on leaves.
- Placement is often random and scattered as diseases are spread through raindrops.
- May appear on lower leaves and the interior of the plant where humidity is higher.
- Brown spots enlarge and grow large enough to touch neighboring spots to form a more prominent blotch.
- Leaf margins may turn yellow.
- Tiny black dots (fruiting bodies of the fungi) appear in the dead spots.
- Blotches grow in size until the entire leaf is brown.
- The leaf falls off the plant.
Severe Symptoms
- Partial or complete premature defoliation
- Reduced growth
- Increased susceptibility to pests and other diseases
Disease Cause
Brown spot, or leaf spot, is a common descriptive term given to several diseases affecting the leaves of plants and trees. Around 85% of diseases exhibiting leaf spots are due to fungus or fungus-like organisms. Sometimes brown spot is caused by a bacterial infection, or insect activity with similar symptoms.
When conditions are warm and the leaf surfaces are wet, fungal spores being transported by wind or rain land on the surface and cling to it. They do not rupture the cell walls but grow in the space between the plant plasma membrane and the plant cell wall. As the spores reproduce, they release toxins and enzymes that cause necrotic spots (i.e., dead tissue) on the leaves, allowing the fungi to consume the products released when the cells degrade.
Solutions
In minor cases of brown spot, there isn’t any need to treat the disease. However, if much of the foliage is affected and defoliation occurs, the plant will benefit from getting rid of the infection. It is recommended to start by applying organic treatment options, working up to the more potent synthetic, chemical fungicides if necessary.
Organic options won’t kill the fungus, but will prevent it from spreading.
- Dissolve ½ teaspoon of baking soda and one teaspoon of liquid soap in a gallon of water. Using a spray bottle, spray on tops and bottoms of leaves until the mixture drips off. Repeat every two weeks until existing spots stop enlarging and new spots no longer appear.
- Spray a copper-based fungicidal soap on the leaves, coating the top and bottom leaf surfaces. Reapply as directed on the product label. Copper penetrates the leaf surface and prevents germination of spores so the fungus cannot spread.
- Apply an all-purpose fungicide to the entire plant, following the label instructions carefully.
Prevention
Like many other diseases, it is easier to prevent brown spot than cure it, and this is done through cultural practices.
- Clear fall leaves from the ground before winter to minimize places where fungi and bacteria can overwinter.
- Maintain good air movement between plants through proper plant spacing.
- Increase air circulation through the center of plants through pruning.
- Thoroughly clean all pruning tools after working with diseased plants.
- Never dispose of disease plant material in a compost pile.
- Avoid overhead watering to keep moisture off of the foliage.
- Keep plants healthy by providing adequate sunlight, water, and fertilizer.
Continue reading in our app - it's better
A database of 400,000+ plants and unlimited guides at your fingertips...
Scan the QR code with your phone camera to download the app
Sign in/sign up
Sign in with Apple
Sign in with Google
Petal blight
Bacterial infections can cause flowers to become soft and rotten.
Overview
Petal blight, sometimes called flower blight, is a fungal disease that only affects the blooms of some ornamental flowering plants. As the infection progresses, it destroys the flower, yet it never damages the vegetative or green parts of the plant.
When flowers are infected, the symptoms look similar to Botrytis blight, but Botrytis also infects dead or dormant vegetative tissue.
The disease was first discovered in Japanese plants in 1919 and in the US in the late 1930s. Presently it is also found in New Zealand, Australia, and parts of Europe. Unfortunately, no plants have high resistance to petal blight, but specific cultivars are more susceptible than others, particularly species with double blooms.
Petal blight infection rates are high when temperatures are mild to warm (optimum temperatures are 15 to 21 ℃) and the weather is misty or rainy.
Overall, petal blight is an aesthetic problem that ruins blossoms. The disease is not harmful to the long-term health of the plant.
Symptom Analysis
The severity of the symptoms varies, depending upon the species of plant infected. Signs of petal blight are commonly seen on the blooms just after they open.
- Pallid spots on colored petals.
- Brown spots on white petals.
- Browning around the petal edges.
- Small spots look water-soaked.
- Spots rapidly enlarge and merge.
- Flowers become limp.
- The entire flower turns light brown, but does not crumble.
- Flowers become slimy at first and then take on a leathery texture.
- A ring of white or gray mycelium can be seen at the base of the petals.
Disease Cause
Petal blight is caused by several different fungi, with each type infecting specific plants. Ovulinia azalea infects azaleas species and cultivars, and rhododendrons. Ciborinia camelliae infects camellia cultivars.
Shortly after blooming, the fungus infects the base of the flowers by the calyx. The fungus produces cell wall-degrading enzymes that destroy flowers within a couple of days. When the flowers fall to the ground, the fungus' hard fruiting bodies fall to the soil as well, overwintering until the following spring.
When temperatures hit the optimum range the following season, spores are transmitted by insects or can spread on wind currents up to about 12 miles. Once in the soil, the pathogen can be active for three to five years.
Solutions
Like other fungal diseases, the progression of petal blight is extremely difficult to stop and impossible to reverse once it infects a plant. The best course of action is to remove all damaged flowers immediately and dispose of them entirely. Do not put them in the compost pile, where spores could grow and spread.
Prevention
- Apply a preventative dose of fungicide as soon as blooms start to show color on the plant. The preventative can be applied as a soil drench or directly to the flowers on the plant.
- Avoid overhead watering during blooming.
- Remove any leaf litter and dead flowers at the end of the season.
- Cover the ground under infected plants with 4” of fresh organic mulch before winter, taking care not to disturb the infected soil.
- Buy bare-root specimens when available.
- When potted plants are purchased, remove the top layer of potting soil and replace it with fresh mulch.
- Plant cultivars that bloom early in the season before the temperatures get high enough for petal blight pathogens to be spreading.
Continue reading in our app - it's better
A database of 400,000+ plants and unlimited guides at your fingertips...
Scan the QR code with your phone camera to download the app
Sign in/sign up
Sign in with Apple
Sign in with Google
Caterpillars
Caterpillars are fleshy moth or butterfly larvae that come in an array of colors, patterns, and even hairstyles. They chew on leaves and flower petals, creating large, irregular holes.
Overview
Caterpillars can cause problems for home gardeners. If not managed, these insects can defoliate a plant in just a matter of days. However, home gardeners face a challenge because these caterpillars eventually turn into beautiful butterflies and moths, which are important for pollination and the general ecosystem.
There are thousands of different species of caterpillars and many will only target certain plants. If caterpillars are posing a problem, they can be removed by hand, or gardeners can use insect-proof netting to protect their valuable plants.
Symptom Analysis
Caterpillars are the larvae of butterflies and moths. During the warmer months, butterflies and moths that visit gardens will lay their eggs on the underside of leaves.
When the tiny eggs hatch, the young larvae emerge and start feeding on the leaves of the plant. Depending on how many larvae have hatched, they can easily defoliate the plant in a very short period of time. Caterpillars will shed their skin as they grow, around 4 or 5 times during this feeding cycle.
Symptoms of caterpillars eating plants appear as holes in the leaves. The edges of the leaves may be eaten away as well, and flowers can be affected as well.
Some are easy to see, but others need to be searched for. This is because their bodies are often camouflaged to look like part of the plant. Gardeners need to look carefully along the stems of the plant as well as under the leaves. Also, look for tiny white, yellow, or brown eggs that can be found in groups on the underside of leaves.
Once the caterpillar is fully grown, it transforms into a pupa or chrysalis. Then, after a period of time that varies according to the species, a butterfly or moth will emerge from the pupa and the cycle begins again.
Solutions
Even though caterpillars are diverse, they all chew on plant parts and can cause significant damage if present in large numbers.
For severe cases:
- Apply insecticide. For an organic solution, spray plants with a Bacillus thuringiensis (Bt), which specifically affects the larval stage of moths and butterflies. Be sure to coat plants, since caterpillars need to ingest Bt for it to be effective. This will not harm other insects.
- Spray a chili extract. Chili seeds can be cooked in water to make a spicy spray that caterpillars don't like. Spray this mixture on the plants, but be aware it will also be spicy to humans.
- Introduce beneficial insects. Release beneficial insects to the garden that eat caterpillars, such as parasitic wasps.
For less severe cases:
- Hand pick. Using gloves, pick off caterpillars on plants and dispose of them in a bucket of soapy water.
- Dust plants with diatomaceous earth. This powder is harmless to humans but irritates caterpillars. Therefore, it will make it difficult for caterpillars to move and eat.
Prevention
Prevention may require less effort than attempts to eradicate infestations that have already begun. Here are our top steps for prevention:
- Monitor plants. Check plants regularly for caterpillar eggs on leaves. If they do not belong to an endangered species, they should be squished.
- Use insect netting. Cover plants with insect netting to prevent butterflies and moths from laying eggs on plants.
- Apply diatomaceous earth. Apply DE to plants early in the season and reapply after rain.
- Encourage plant diversity. This will attract predatory insects including parasitic wasps.
Continue reading in our app - it's better
A database of 400,000+ plants and unlimited guides at your fingertips...
Scan the QR code with your phone camera to download the app
Sign in/sign up
Sign in with Apple
Sign in with Google
Underwatering
Leaves may wilt for a variety of reasons.
Overview
Underwatering plants is one of the quickest ways to kill them. This is something that most gardeners are well aware of. Unfortunately, knowing exactly how much water a plant needs can be tricky, especially considering that underwatering and overwatering present similar symptoms in plants.
Therefore, it’s important to be vigilant and attentive to each plants’ individual needs.
Symptom Analysis
As mentioned earlier, overwatering and underwatering present similar symptoms in plants. These symptoms include poor growth, wilted leaves, defoliation, and brown leaf tips or margins. Ultimately, both underwatering and overwatering can lead to the death of a plant.
The easiest way to determine whether a plant has too much water or too little is to look at the leaves. If underwatering is the culprit, the leaves will look brown and crunchy, while if it’s overwatering, they will appear yellow or a pale green in color.
When this issue first begins, there may be no noticeable symptoms at all, particularly in hardy or drought-tolerant plants. However, they will begin to wilt once they start suffering from a lack of water. The edges of the plant’s leaves will become brown or curled. Soil pulling away from the edges of the planter is a telltale sign, or a crispy, brittle stem.
Prolonged underwatering can cause a plant’s growth to become stunted. The leaves might drop and the plant can be more susceptible to pest infestations, too.
Disease Cause
Underwatering is caused by, quite simply, not watering plants often or deeply enough. There is a heightened risk of underwatering if any of these situations apply:
- Extreme heat and dry weather (when growing outdoors)
- Grow lights or indoor lighting that is too bright or intense for the type of plant
- Using fast-draining growing media such as sand
Solutions
The easiest (and most obvious) way to address underwatering is to fully hydrate the plant. However, this must be done carefully. A common mistake that many gardeners make is to douse their underwatered plants with water. This can overwhelm the roots of the plant and shock its system, something that can be even more damaging than the lack of water to begin with.
Instead, water thoroughly and slowly, taking breaks to let the water slowly saturate through the soil to get to the roots. Use room temperature water, as cold water might be too much of a shock.
In the future, shorten the time between waterings. A good rule of thumb is to check the soil around each plant daily. If it’s dry to at least two inches down, it’s time to water. If a container plant is repeatedly drying out very quickly, repotting into a slower-draining container might be a good idea, too.
Prevention
Always check the soil before watering. If the top inch of soil feels moist, though not wet, the watering is perfect. If it’s dry, water it immediately. If it feels soggy, you avoid watering until it dries out a bit more.
Also, make sure the lighting is sufficient for the species. Plants grow faster and need more water when there is intense light or lots of heat. Being aware of these conditions and modifying them, if possible, is a good way to prevent underwatering. Many container plants are potted in soil mixtures mean to be well-draining. Adding materials that retain moisture, like compost or peat moss, can also prevent these symptoms.
Other tips to prevent underwatering include:
- Choose pots with adequately-sized drainage holes
- Avoid warm temperatures
- Use large pots with additional soil (these take longer to dry out)
- Avoid terracotta pots, which lose water quickly
Continue reading in our app - it's better
A database of 400,000+ plants and unlimited guides at your fingertips...
Scan the QR code with your phone camera to download the app
Sign in/sign up
Sign in with Apple
Sign in with Google
More Info
Plant Type
Herb
Scientific Classification
Find your perfect green friends.
Plan your green oasis based on your criteria: plant type, pet safety, skill level, sites, and more.
Related Articles
Useful Tips
Most Common Herb
Plant Collection Most Common Herb Fragrant plantain lily See More The trademark feature of Asia-native plantain lilies is the numerous glossy oval leaves with deep parallel veins. The Fragrant plantain lily is additionally decorated with strongly fragrant, trumpet-shaped, large white flowers, which are unique in the genus. Hosta plantaginea is one of the favorite cultivatedContinue reading “Most Common Herb”
Read More ![more]()
Useful Tips
Best Perennial Plant to Grow
Plant Collection Best Perennial Plant to Grow Orange daylily See More The Orange daylily is a perennial plant known for its captivating lily-like blooms. Its natural habitats are meadows and forests, but it is also a common garden plant in temperate regions around the world. Each individual flower lasts only a day, but the plantContinue reading “Best Perennial Plant to Grow”
Read More ![more]()
Useful Tips
Best Perennial Plant to Grow
Plant Collection Best Perennial Plant to Grow China rose See More The China rose (Rosa chinensis) is a Southwest China native. The plant has been cultivated for so long that it has become hard to tell the difference between wild and cultivated varieties. With medium-sized clusters of flowers and a long blooming season, it isContinue reading “Best Perennial Plant to Grow”
Read More ![more]()
Useful Tips
Most Common Herb
Plant Collection Most Common Herb Golden pothos See More The Golden pothos is a popular flowering house plant that’s commonly seen in Australia, Asia, and the West Indies. It goes by many nicknames, including “devil’s ivy,” because it is so hard to kill, and can grow in the dark. Golden pothos has poisonous sap, soContinue reading “Most Common Herb”
Read More ![more]()
View More Articles
Continue reading in our app - it's better
A database of 400,000+ plants and unlimited guides at your fingertips...
Your Ultimate Guide to Plants
Identify, grow, and nurture the better way!
17,000 local species +400,000 global species studied
Nearly 5 years of research
80+ scholars in botany and gardening
Botanist in your pocket
Scan the QR code with your phone camera to download the app
Sign in/sign up
Sign in with Apple
Sign in with Google
Logged in!
About
Care Guide
More About How-Tos
Pests & Diseases
More Info
Related Articles
Add to My Garden Chinese peony 'Jan van Leeuwen'
Paeonia lactiflora 'Jan van Leeuwen'
Also known as: Fragrant peony 'Jan van Leeuwen'
Chinese peony 'Jan van Leeuwen' delights the eye with bowl-shaped satin-white flowers with yellow centers that bloom from late spring to early summer. Foliage is dark green and dense. This is a cultivar of Chinese peony, named after the originator Jan van Leeuwen in 1928. This lovely cultivar is sought after and treasured by peony enthusiasts.
Hardiness Zones
5 to 8
Care Guide for Chinese peony 'Jan van Leeuwen'
Water
Average water needs, watering when the top 3 cm of soil has dried out.
Soil
Chalky, Sand, Acidic, Neutral, Alkaline
Sunlight
Full sun, Partial sun
Hardiness Zones
5 to 8
Know the light your plants really get.
Find the best spots for them to optimize their health, simply using your phone.
Download the App
Download
More About How-Tos
Common Pests & Diseases
Common issues for Chinese peony 'Jan van Leeuwen' based on 10 million real cases
Brown spot
This infection can cause brown spots or patches to appear on the plant.
Solutions: In minor cases of brown spot, there isn’t any need to treat the disease. However, if much of the foliage is affected and defoliation occurs, the plant will benefit from getting rid of the infection. It is recommended to start by applying organic treatment options, working up to the more potent synthetic, chemical fungicides if necessary. Organic options won’t kill the fungus, but will prevent it from spreading. Dissolve ½ teaspoon of baking soda and one teaspoon of liquid soap in a gallon of water. Using a spray bottle, spray on tops and bottoms of leaves until the mixture drips off. Repeat every two weeks until existing spots stop enlarging and new spots no longer appear. Spray a copper-based fungicidal soap on the leaves, coating the top and bottom leaf surfaces. Reapply as directed on the product label. Copper penetrates the leaf surface and prevents germination of spores so the fungus cannot spread. Apply an all-purpose fungicide to the entire plant, following the label instructions carefully.
Learn More ![more]()
Petal blight
Bacterial infections can cause flowers to become soft and rotten.
Solutions: Like other fungal diseases, the progression of petal blight is extremely difficult to stop and impossible to reverse once it infects a plant. The best course of action is to remove all damaged flowers immediately and dispose of them entirely. Do not put them in the compost pile, where spores could grow and spread.
Learn More ![more]()
Caterpillars
Caterpillars are fleshy moth or butterfly larvae that come in an array of colors, patterns, and even hairstyles. They chew on leaves and flower petals, creating large, irregular holes.
Solutions: Even though caterpillars are diverse, they all chew on plant parts and can cause significant damage if present in large numbers. For severe cases: Apply insecticide. For an organic solution, spray plants with a Bacillus thuringiensis (Bt), which specifically affects the larval stage of moths and butterflies. Be sure to coat plants, since caterpillars need to ingest Bt for it to be effective. This will not harm other insects. Spray a chili extract. Chili seeds can be cooked in water to make a spicy spray that caterpillars don't like. Spray this mixture on the plants, but be aware it will also be spicy to humans. Introduce beneficial insects. Release beneficial insects to the garden that eat caterpillars, such as parasitic wasps. For less severe cases: Hand pick. Using gloves, pick off caterpillars on plants and dispose of them in a bucket of soapy water. Dust plants with diatomaceous earth. This powder is harmless to humans but irritates caterpillars. Therefore, it will make it difficult for caterpillars to move and eat.
Learn More ![more]()
Underwatering
Leaves may wilt for a variety of reasons.
Solutions: The easiest (and most obvious) way to address underwatering is to fully hydrate the plant. However, this must be done carefully. A common mistake that many gardeners make is to douse their underwatered plants with water. This can overwhelm the roots of the plant and shock its system, something that can be even more damaging than the lack of water to begin with. Instead, water thoroughly and slowly, taking breaks to let the water slowly saturate through the soil to get to the roots. Use room temperature water, as cold water might be too much of a shock. In the future, shorten the time between waterings. A good rule of thumb is to check the soil around each plant daily. If it’s dry to at least two inches down, it’s time to water. If a container plant is repeatedly drying out very quickly, repotting into a slower-draining container might be a good idea, too.
Learn More ![more]()
Treat and prevent plant diseases.
AI-powered plant doctor helps you diagnose plant problems in seconds.
Download the App
Brown spot
This infection can cause brown spots or patches to appear on the plant.
Overview
Discolored spots on the foliage of plants are one of the most common disease problems people observe. These spots are caused by fungal and bacterial diseases, with most infections related to a fungal pathogen.
Brown spot can occurs on all houseplants, flowering ornamentals, vegetable plants, and leaves of trees, bushes, and shrubs. No plants are resistant to it, and the problem is worse in warm, wet environments. It can occur at any point in the life stage as long as leaves are present.
Small brownish spots appear on the foliage and enlarge as the disease progresses. In severe cases, the plant or tree is weakened when the lesions interrupt photosynthesis or cause defoliation.
Symptom Analysis
In most cases, brown spot only affects a small percentage of the whole plant, appearing on a small amount of the leaves. A small infection only puts minor stress on the plant. However, if left untreated and the disease progresses over numerous seasons, it will severely impact the health and productivity of the infected specimen.
- Sporulation begins (reproduction of the fungal spores), and tiny spots appear on leaves.
- Placement is often random and scattered as diseases are spread through raindrops.
- May appear on lower leaves and the interior of the plant where humidity is higher.
- Brown spots enlarge and grow large enough to touch neighboring spots to form a more prominent blotch.
- Leaf margins may turn yellow.
- Tiny black dots (fruiting bodies of the fungi) appear in the dead spots.
- Blotches grow in size until the entire leaf is brown.
- The leaf falls off the plant.
Severe Symptoms
- Partial or complete premature defoliation
- Reduced growth
- Increased susceptibility to pests and other diseases
Disease Cause
Brown spot, or leaf spot, is a common descriptive term given to several diseases affecting the leaves of plants and trees. Around 85% of diseases exhibiting leaf spots are due to fungus or fungus-like organisms. Sometimes brown spot is caused by a bacterial infection, or insect activity with similar symptoms.
When conditions are warm and the leaf surfaces are wet, fungal spores being transported by wind or rain land on the surface and cling to it. They do not rupture the cell walls but grow in the space between the plant plasma membrane and the plant cell wall. As the spores reproduce, they release toxins and enzymes that cause necrotic spots (i.e., dead tissue) on the leaves, allowing the fungi to consume the products released when the cells degrade.
Solutions
In minor cases of brown spot, there isn’t any need to treat the disease. However, if much of the foliage is affected and defoliation occurs, the plant will benefit from getting rid of the infection. It is recommended to start by applying organic treatment options, working up to the more potent synthetic, chemical fungicides if necessary.
Organic options won’t kill the fungus, but will prevent it from spreading.
- Dissolve ½ teaspoon of baking soda and one teaspoon of liquid soap in a gallon of water. Using a spray bottle, spray on tops and bottoms of leaves until the mixture drips off. Repeat every two weeks until existing spots stop enlarging and new spots no longer appear.
- Spray a copper-based fungicidal soap on the leaves, coating the top and bottom leaf surfaces. Reapply as directed on the product label. Copper penetrates the leaf surface and prevents germination of spores so the fungus cannot spread.
- Apply an all-purpose fungicide to the entire plant, following the label instructions carefully.
Prevention
Like many other diseases, it is easier to prevent brown spot than cure it, and this is done through cultural practices.
- Clear fall leaves from the ground before winter to minimize places where fungi and bacteria can overwinter.
- Maintain good air movement between plants through proper plant spacing.
- Increase air circulation through the center of plants through pruning.
- Thoroughly clean all pruning tools after working with diseased plants.
- Never dispose of disease plant material in a compost pile.
- Avoid overhead watering to keep moisture off of the foliage.
- Keep plants healthy by providing adequate sunlight, water, and fertilizer.
Continue reading in our app - it's better
A database of 400,000+ plants
unlimited guides at your fingertips...
unlimited guides at your fingertips...
Sign in/sign up
Petal blight
Bacterial infections can cause flowers to become soft and rotten.
Overview
Petal blight, sometimes called flower blight, is a fungal disease that only affects the blooms of some ornamental flowering plants. As the infection progresses, it destroys the flower, yet it never damages the vegetative or green parts of the plant.
When flowers are infected, the symptoms look similar to Botrytis blight, but Botrytis also infects dead or dormant vegetative tissue.
The disease was first discovered in Japanese plants in 1919 and in the US in the late 1930s. Presently it is also found in New Zealand, Australia, and parts of Europe. Unfortunately, no plants have high resistance to petal blight, but specific cultivars are more susceptible than others, particularly species with double blooms.
Petal blight infection rates are high when temperatures are mild to warm (optimum temperatures are 15 to 21 ℃) and the weather is misty or rainy.
Overall, petal blight is an aesthetic problem that ruins blossoms. The disease is not harmful to the long-term health of the plant.
Symptom Analysis
The severity of the symptoms varies, depending upon the species of plant infected. Signs of petal blight are commonly seen on the blooms just after they open.
- Pallid spots on colored petals.
- Brown spots on white petals.
- Browning around the petal edges.
- Small spots look water-soaked.
- Spots rapidly enlarge and merge.
- Flowers become limp.
- The entire flower turns light brown, but does not crumble.
- Flowers become slimy at first and then take on a leathery texture.
- A ring of white or gray mycelium can be seen at the base of the petals.
Disease Cause
Petal blight is caused by several different fungi, with each type infecting specific plants. Ovulinia azalea infects azaleas species and cultivars, and rhododendrons. Ciborinia camelliae infects camellia cultivars.
Shortly after blooming, the fungus infects the base of the flowers by the calyx. The fungus produces cell wall-degrading enzymes that destroy flowers within a couple of days. When the flowers fall to the ground, the fungus' hard fruiting bodies fall to the soil as well, overwintering until the following spring.
When temperatures hit the optimum range the following season, spores are transmitted by insects or can spread on wind currents up to about 12 miles. Once in the soil, the pathogen can be active for three to five years.
Solutions
Like other fungal diseases, the progression of petal blight is extremely difficult to stop and impossible to reverse once it infects a plant. The best course of action is to remove all damaged flowers immediately and dispose of them entirely. Do not put them in the compost pile, where spores could grow and spread.
Prevention
- Apply a preventative dose of fungicide as soon as blooms start to show color on the plant. The preventative can be applied as a soil drench or directly to the flowers on the plant.
- Avoid overhead watering during blooming.
- Remove any leaf litter and dead flowers at the end of the season.
- Cover the ground under infected plants with 4” of fresh organic mulch before winter, taking care not to disturb the infected soil.
- Buy bare-root specimens when available.
- When potted plants are purchased, remove the top layer of potting soil and replace it with fresh mulch.
- Plant cultivars that bloom early in the season before the temperatures get high enough for petal blight pathogens to be spreading.
Continue reading in our app - it's better
A database of 400,000+ plants
unlimited guides at your fingertips...
unlimited guides at your fingertips...
Sign in/sign up
Caterpillars
Caterpillars are fleshy moth or butterfly larvae that come in an array of colors, patterns, and even hairstyles. They chew on leaves and flower petals, creating large, irregular holes.
Overview
Caterpillars can cause problems for home gardeners. If not managed, these insects can defoliate a plant in just a matter of days. However, home gardeners face a challenge because these caterpillars eventually turn into beautiful butterflies and moths, which are important for pollination and the general ecosystem.
There are thousands of different species of caterpillars and many will only target certain plants. If caterpillars are posing a problem, they can be removed by hand, or gardeners can use insect-proof netting to protect their valuable plants.
Symptom Analysis
Caterpillars are the larvae of butterflies and moths. During the warmer months, butterflies and moths that visit gardens will lay their eggs on the underside of leaves.
When the tiny eggs hatch, the young larvae emerge and start feeding on the leaves of the plant. Depending on how many larvae have hatched, they can easily defoliate the plant in a very short period of time. Caterpillars will shed their skin as they grow, around 4 or 5 times during this feeding cycle.
Symptoms of caterpillars eating plants appear as holes in the leaves. The edges of the leaves may be eaten away as well, and flowers can be affected as well.
Some are easy to see, but others need to be searched for. This is because their bodies are often camouflaged to look like part of the plant. Gardeners need to look carefully along the stems of the plant as well as under the leaves. Also, look for tiny white, yellow, or brown eggs that can be found in groups on the underside of leaves.
Once the caterpillar is fully grown, it transforms into a pupa or chrysalis. Then, after a period of time that varies according to the species, a butterfly or moth will emerge from the pupa and the cycle begins again.
Solutions
Even though caterpillars are diverse, they all chew on plant parts and can cause significant damage if present in large numbers.
For severe cases:
- Apply insecticide. For an organic solution, spray plants with a Bacillus thuringiensis (Bt), which specifically affects the larval stage of moths and butterflies. Be sure to coat plants, since caterpillars need to ingest Bt for it to be effective. This will not harm other insects.
- Spray a chili extract. Chili seeds can be cooked in water to make a spicy spray that caterpillars don't like. Spray this mixture on the plants, but be aware it will also be spicy to humans.
- Introduce beneficial insects. Release beneficial insects to the garden that eat caterpillars, such as parasitic wasps.
For less severe cases:
- Hand pick. Using gloves, pick off caterpillars on plants and dispose of them in a bucket of soapy water.
- Dust plants with diatomaceous earth. This powder is harmless to humans but irritates caterpillars. Therefore, it will make it difficult for caterpillars to move and eat.
Prevention
Prevention may require less effort than attempts to eradicate infestations that have already begun. Here are our top steps for prevention:
- Monitor plants. Check plants regularly for caterpillar eggs on leaves. If they do not belong to an endangered species, they should be squished.
- Use insect netting. Cover plants with insect netting to prevent butterflies and moths from laying eggs on plants.
- Apply diatomaceous earth. Apply DE to plants early in the season and reapply after rain.
- Encourage plant diversity. This will attract predatory insects including parasitic wasps.
Continue reading in our app - it's better
A database of 400,000+ plants
unlimited guides at your fingertips...
unlimited guides at your fingertips...
Sign in/sign up
Underwatering
Leaves may wilt for a variety of reasons.
Overview
Underwatering plants is one of the quickest ways to kill them. This is something that most gardeners are well aware of. Unfortunately, knowing exactly how much water a plant needs can be tricky, especially considering that underwatering and overwatering present similar symptoms in plants.
Therefore, it’s important to be vigilant and attentive to each plants’ individual needs.
Symptom Analysis
As mentioned earlier, overwatering and underwatering present similar symptoms in plants. These symptoms include poor growth, wilted leaves, defoliation, and brown leaf tips or margins. Ultimately, both underwatering and overwatering can lead to the death of a plant.
The easiest way to determine whether a plant has too much water or too little is to look at the leaves. If underwatering is the culprit, the leaves will look brown and crunchy, while if it’s overwatering, they will appear yellow or a pale green in color.
When this issue first begins, there may be no noticeable symptoms at all, particularly in hardy or drought-tolerant plants. However, they will begin to wilt once they start suffering from a lack of water. The edges of the plant’s leaves will become brown or curled. Soil pulling away from the edges of the planter is a telltale sign, or a crispy, brittle stem.
Prolonged underwatering can cause a plant’s growth to become stunted. The leaves might drop and the plant can be more susceptible to pest infestations, too.
Disease Cause
Underwatering is caused by, quite simply, not watering plants often or deeply enough. There is a heightened risk of underwatering if any of these situations apply:
- Extreme heat and dry weather (when growing outdoors)
- Grow lights or indoor lighting that is too bright or intense for the type of plant
- Using fast-draining growing media such as sand
Solutions
The easiest (and most obvious) way to address underwatering is to fully hydrate the plant. However, this must be done carefully. A common mistake that many gardeners make is to douse their underwatered plants with water. This can overwhelm the roots of the plant and shock its system, something that can be even more damaging than the lack of water to begin with.
Instead, water thoroughly and slowly, taking breaks to let the water slowly saturate through the soil to get to the roots. Use room temperature water, as cold water might be too much of a shock.
In the future, shorten the time between waterings. A good rule of thumb is to check the soil around each plant daily. If it’s dry to at least two inches down, it’s time to water. If a container plant is repeatedly drying out very quickly, repotting into a slower-draining container might be a good idea, too.
Prevention
Always check the soil before watering. If the top inch of soil feels moist, though not wet, the watering is perfect. If it’s dry, water it immediately. If it feels soggy, you avoid watering until it dries out a bit more.
Also, make sure the lighting is sufficient for the species. Plants grow faster and need more water when there is intense light or lots of heat. Being aware of these conditions and modifying them, if possible, is a good way to prevent underwatering. Many container plants are potted in soil mixtures mean to be well-draining. Adding materials that retain moisture, like compost or peat moss, can also prevent these symptoms.
Other tips to prevent underwatering include:
- Choose pots with adequately-sized drainage holes
- Avoid warm temperatures
- Use large pots with additional soil (these take longer to dry out)
- Avoid terracotta pots, which lose water quickly
Continue reading in our app - it's better
A database of 400,000+ plants
unlimited guides at your fingertips...
unlimited guides at your fingertips...
Sign in/sign up
More Info
Plant Type
Herb
Scientific Classification
Find your perfect green friends.
Plan your green oasis based on your criteria: plant type, pet safety, skill level, sites, and more.
Download the App
Related Articles
Most Common Herb
# Useful Tips
Best Perennial Plant to Grow
# Useful Tips
Best Perennial Plant to Grow
# Useful Tips
Most Common Herb
# Useful Tips
Discover more articles?
Read More 
Your Ultimate Guide to Plants
Identify, grow, and nurture the better way!
17,000 local species +400,000 global species studied
Nearly 5 years of research
80+ scholars in botany and gardening
Sign in/sign up
Continue reading in our app - it's better
A database of 400,000+ plants
unlimited guides at your fingertips...
unlimited guides at your fingertips...
Sign in/sign up
Lighting
Indoor
Indoor
Outdoor
Choose a site here for personalized care tips. Requirements
Full sun
Ideal
Above 6 hours sunlight
Partial sun
Tolerance
About 3-6 hours sunlight
Watch how sunlight gracefully moves through your garden, and choose spots that provide the perfect balance of light and shade for your plants, ensuring their happiness. 
Discover information about plant diseases, toxicity, weed control and more.
Temperature
Indoor
Indoor
Outdoor
Choose a site here for personalized care tips. Requirements
Ideal
Tolerable
Unsuitable
Just like people, each plant has its own preferences. Learn about your plants' temperature needs and create a comforting environment for them to flourish. As you care for your plants, your bond with them will deepen. Trust your intuition as you learn about their temperature needs, celebrating the journey you share. Lovingly monitor the temperature around your plants and adjust their environment as needed. A thermometer can be your ally in this heartfelt endeavor. Be patient and gentle with yourself as you explore your plants' temperature needs. Cherish your successes, learn from challenges, and nurture your garden with love, creating a haven that reflects the warmth of your care. Discover information about plant diseases, toxicity, weed control and more.
