Black walnut (Juglans nigra) Flower, Leaf, Care, Uses

Established Black walnut trees will need watering every three weeks during the active growing season, and less if the weather is rainy. Do not let the soil dry out completely between waterings, especially if the tree is younger or the weather is hot, as Black walnut does not tolerate dry conditions.

Fertilization

Black walnut needs a generous helping of time-released fertilizer when repotting or planting. Fertilize established trees twice a year. In early spring, use a nitrogen-heavy fertilizer; in early summer, use a balanced 15-15-15 fertilizer.

Pruning

Trim the dead, diseased, overgrown branches in winter.

Soil

Sand, Loam, Clay, Chalky, Acidic, Neutral, Alkaline

Sunlight

Full sun, Partial sun

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Black walnut

Water

Every 1-2 weeks

Sunlight

Full sun

Hardiness Zones

4 to 10

Planting Time

Spring, Fall, Winter

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Questions About Black walnut

Watering

Pruning

Sunlight

Temperature

Fertilizing

What's the best method to water my Black walnut?

You might want to put a garden hose at the plant base to ensure that you're promoting excellent root development. Avoid directly spraying the leaves, and know that the leaves will require more watering if they are outdoors and facing direct sunlight. You can also use bubblers that you can put on to each plant to moisten the roots. Also, use soaker hoses that can cover the entire garden or bed when adding or removing plants to push the roots deeply. Drain any excess water and wait for the soil to dry before watering. Water at ground level to prevent diseases. On a sunny day, you might want to spray the entire bush with water. Whether potted or in-ground, please remember Black walnut prefers deep watering over light sprinkling.

What should I do if I water Black walnut too much/too little?

An overwatered Black walnut can start to have leaves that turn yellow, drop off and wilt. The plant can also look dull and unhealthy, with signs of mushy stems. When they are beginning to show these signs, it's best to adjust your schedule whenever possible.

The wilting can also be a sign of under watering as well. You might see that the leaves begin to turn crispy and dry while the overwatered ones will have soft wilted leaves. Check the soil when it is dry and watering is not enough, give it a full watering in time. Enough water will make the Black walnut recover again, but the plant will still appear dry and yellow leaves after a few days due to the damaged root system. Once it return to normal, the leave yellowing will stop .

Always check the moisture levels at the pot when you have the Black walnut indoors. Avoid overwatering indoors and see if there are signs of black spots. If these are present, let the soil dry in the pot by giving it a few days of rest from watering.

Overwatering can lead to root rot being present in your plant. If this is the case, you might want to transfer them into a different pot, especially if you see discolored and slimy roots. Always prevent root rot as much as possible, and don't let the soil become too soggy.

You should dig a little deeper when you plant your Black walnut outdoors. When you check with your fingers and notice that the soil is too dry, it could mean underwatering. Adequate watering is required to help the plant recover.

How often should I water my Black walnut?

The Black walnut likes deep and infrequent watering. You would want to soak them in a gallon of water each time, especially when they are planted in pots. The water storage of flower pots is limited and the soil will dry out faster. Watering is required every 3 to 5 days when living in a cold region. Water it early in the morning when the soil is dry, outdoors or indoors. You can also determine if watering is needed by checking the soil inside. When the top 2-3 inches of soil is dry, it is time to give the plant a full watering. During hot days, you may need to check the moisture daily, as the heat can quickly dry out the soil in the pot.

Irrigation of the soil is also required if you have a garden. When you live in a hot climate, you might want to water once a week. Only water when you notice that about 2 to 3 inches of soil become too dry outdoors or indoors. Consider the amount of rainwater on the plant and ensure not to add to it to prevent root rot.You may not need additional watering of the plants if there is a lot of rainfall.Black walnut generally grows during spring and fall. When they are outdoors, you need to add mulch about 3 to 4 inches deep to conserve more water.

You need to water the plants more frequently in sandy soil because this type tends to drain faster. However, with the clay one, you need to water this less frequently where you could go for 2-3 days to dry the plant and not develop any root rot. You could mark the date on the calendar whenever you water and when you notice that the leaves are starting to droop. This can mean that you might be a day late.

How much water do I need to give my Black walnut?

The Black walnut generally needs about a gallon of water each schedule,With the potted plants, you might want to water them deeply until you see that the water is dripping at the bottom of the pot. Then, wait for the soil to dry before watering them again. You can use a water calculator or a moisture meter to determine the amount you've given to your plant in a week. Provide plenty of water, especially in the flowering period, but let the moisture evaporate afterwards to prevent root rot.

If Black walnut is planted outdoor with adequate rainfall, it may not need additional watering. When Black walnut is young or newly planted, make sure it gets 1-2 inches of rain per week. As Black walnut continues to grow, it can survive entirely on rainfall. Only when the weather is too hot, or when there is no rainfall at all for 2-3 weeks, then consider giving Black walnut a full watering during the cooler moment of the day to prevent the plant from suffering from high heat damage. Additional watering will be required during persistent dry spells.

Should I adjust the watering frequency for my Black walnut according to different seasons or climates?

The Black walnut needs outdoors come from rain, with only persistent dry weather requiring watering. Throughout the spring and fall growing seasons, the soil needs to be kept moist but not soggy, and alternating dry and moist soil conditions will allow the Black walnut to grow well. Throughout the summer, hot weather can cause water to evaporate too quickly, and if there is a lack of rainfall, you will need to water more frequently and extra to keep it moist.

Usually, the Black walnut will need less water during the winter. Since the Black walnut will drop their leaves and go dormant, you can put them into a well-draining but moisture-retentive soil mixture like the terracotta to help the water evaporate quicker. Once your Black walnut growing outdoors begins to leaf out and go dormant, you can skip watering altogether and in most cases Black walnut can rely on the fall and winter rains to survive the entire dormant period.

After the spring, you can cultivate your Black walnut and encourage it to grow and bloom when the temperature becomes warmer.This plant is not generally a fan of ponding or drought when flowering. You must ensure that the drainage is good at all times, especially during the winter.

When the plant is in a pot, the plant has limited root growth. Keep them well-watered, especially if they are planted in pots during summer. They don't like cold and wet roots, so provide adequate drainage, especially if they are still growing.

It's always best to water your Black walnut’s diligently. Get the entire root system into a deep soak at least once or twice a week, depending on the weather. It's best to avoid shallow sprinkles that reach the leaves since they generally encourage the growth of fungi and don't reach deep into the roots. Don't allow the Black walnut’s to dry out completely in the fall or winter, even if they are already dormancy.

Don't drown the plants because they generally don't like sitting in water for too long. They can die during winter if the soil does not drain well. Also, apply mulch whenever possible to reduce stress, conserve water, and encourage healthy blooms.

What should I be careful with when I water my Black walnut in different seasons, climates, or during different growing periods?

If planting in the ground, Black walnut mostly relies on rain. However, if there is no rainfall for 2-3 weeks, you may need to give proper consideration to giving the plants a deep watering. If watering Black walnut in summer, you should try to do it in the morning. A large temperature difference between the water temperature and the root system can stress the roots. You need to avoid watering the bushes when it's too hot outside. Start mulching them during the spring when the ground is not too cold.

The age of the plants matter. Lack of water is one of the most common reasons the newly planted ones fail to grow. After they are established, you need to ease off the watering schedule.

Reduce watering them during the fall and winter, especially if they have a water-retaining material in the soil. The dry winds in winter can dry them out, and the newly planted ones can be at risk of drought during windy winter, summer, and fall. Windy seasons mean that there's more watering required. The ones planted in the pot tend to dry out faster, so they need more watering. Once you see that they bloom less, the leaves begin to dry up.

Potted plants are relatively complex to water and fluctuate in frequency. Always be careful that the pot-planted plant don't sit in the water. Avoid putting them in containers with saucers, bowls, and trays. Too much watering in the fall can make the foliage look mottled or yellowish. It's always a good idea to prevent overwatering them regardless of the current climate or season that you might have. During the months when Black walnut begins to flower, you might want to increase the watering frequency but give it a rest once they are fully grown.

Give them an adequate amount of water once every 3 to 5 days but don't give them regular schedules. Make sure the soil is dry by sticking your finger in the pot, or use a moisture meter if you're unsure if it's the right time. Too much root rot can cause them to die, so be careful not to overwater or underwater regardless of the climate or season you have in your area.

Why is watering my Black walnut important?

Watering the Black walnut helps transport the needed nutrients from the soil to the rest of the plant. The moisture will keep this species healthy if you know how much water to give. The watering requirements will depend on the weather in your area and the plant's soil.

The Black walnut thrives on moist soil, but they can't generally tolerate waterlogging. Ensure to provide enough mulch when planted on the ground and never fall into the trap of watering too little. They enjoy a full can of watering where the water should be moist at the base when they are planted in a pot to get the best blooms.

If they are grown as foliage, you need to water them up to a depth of 10 to 20 inches so they will continue to grow. If it's raining, refrain from watering and let them get the nutrients they need from the rainwater.

Is pruning necessary for my Black walnut?

Despite having a relatively fast habit of growth, Black walnut does not require very much pruning. It is not necessary to routinely prune this tree, however, it does require some pruning every once in a while. Pruning can be done to tidy this tree up and remove any diseased or damaged foliage. Or Black walnut can be pruned for shaping.

When is the best time to prune my Black walnut?

Black walnut should be pruned as needed. Typically, these trees should be pruned to remove any damaged, yellowing, dying, or dead foliage. It is also necessary to prune this plant to remove any shoots that are congested or are crossing. The best time to prune Black walnut is between late winter to early spring. This is the period when pruning causes the least damage to the plant.

How can I prune my Black walnut?

Pruning Black walnut is a fairly easy task if you know what to look for. To prune these trees, you will need a pair of sharp pruning shears. Using your pruning shears, remove any damaged or diseased parts of the tree. Keep an eye out for any shoots that are becoming congested or are beginning to cross and remove them. Ideally, you should steer clear from pruning any of the tree’s lower limbs. Leaving these intact will allow the tree to have a more natural and open form. Additionally, leaving the lower limbs alone will help to prevent any disease-inducing stress, as well as suckers from forming.

What should I do after pruning my Black walnut?

There are no special requirements to follow after you have pruned your Black walnut. It is recommended, however, that you dispose of any diseased foliage that has been removed from the tree away from any other plants. This is to avoid spreading the disease to other plants. After pruning your Black walnut, you may apply a fertilizer treatment to encourage faster growth. Do not water the plants immediately after pruning as this can lead to fungal infestation of the plants through the wounds.

What should I be careful with when pruning my Black walnut during different growing stages?

The best time to prune Black walnut is between late winter to early spring. This is the period when pruning causes the least damage to the plant. Keep an eye out for any shoots that are becoming congested or are beginning to cross and remove them. Ideally, you should steer clear from pruning any of the tree’s lower limbs. Leaving these intact will allow the tree to have a more natural and open form. This will increase ventilation and light, reduce disease infection and allow Black walnut to grow more vigorously. When pruning branches you need to leave the strong ones and remove the weak ones, keeping healthy auxiliary branches that grow outwards at about 45 degrees. Branches that are too angled or too small should be removed. Pruning Saw is required if the branch is more than three quarters of an inch in size, pruning should be done in the direction of the "Branch bark ridge" to the "Branch collar" to allow for good healing. Branches that require a saw need to be pruned using the "three-cut method", which prevents the bark of the branch from tearing and creating cracks in the trunk, which can be detrimental to the recovery of the plant. Finally, you may prefer to just trim off dead or damaged portions of the plant to keep it looking its best as if it's possible. This can be done at any time of year. Diseased or damaged stems should be cut right at the soil line and removed completely.

Are there any tips for pruning my Black walnut?

The best thing to remember about Black walnut is that they do not require routine pruning. Your tree will likely grow better if you prune it as and when it is necessary and no more than that. Additionally, you should also keep in mind that it is better to leave the lower limbs of this tree alone to prevent stress-induced diseases from attacking your tree. Different diameter branches require different pruning tools. If the tree is too tall, pruning needs to be done safely or by a professional.

How much/long should Black walnut get sunlight per day for healthy growth?

For healthy growth, make sure that Black walnut receives at least 3–6 hours of sun each day. This is actually a minimum requirement—most plants that can handle part sun can also thrive in full sun, but because they require less light for photosynthesis, they are more flexible than plants that require full sun or part shade.

What type of sunlight does Black walnut need?

Black walnut does best with exposure to full or part sun. They will perform best with direct morning light, but in summer they need protection from the strong afternoon sun. In temperate environments, too much hot afternoon sun can burn the leaves, damaging the plant's appearance and health.

Can sunlight damage Black walnut? How to protect Black walnut from the sun and heat damage?

Black walnut planted indoors can easily be damaged by direct sunlight when it's moved outdoors. The best way to prevent sunburns from overexposure is to move pots gradually from a shaded area to a brighter spot, gradually. But even plants that are acclimated to the summer sun can be damaged by extreme heat. In a heatwave, it is important to keep the soil consistently moist so that plants can cope with excessive levels of heat. Moving plants in containers to areas with afternoon shade or erecting a shade cloth over them can protect sensitive Black walnut during extreme weather events.

Does Black walnut need to avoid sun exposure? / Should I protect Black walnut from the sun?

While bright morning sun and some full sun exposure can be highly beneficial for Black walnut, the harsh, hot midday sun of summer can be too much to handle.

If planted in the ground, the summer sun will usually ramp up slowly enough through the season for Black walnut to gradually adapt to its intensity. But a potted plant that has been indoors or in a protected location will often suffer injury when placed suddenly into a location where the direct summer sun reaches it in the hottest part of the day.

To protect this plant from the brutal afternoon summer sun, plant or place it in an understory location where it is shaded at midday by taller trees and plants or by a building or landscape feature.

What will happen if Black walnut gets inadequate sunlight?

When Black walnut receives too little sun, they may become pale green or display drooping, yellow leaves. While some leaf drop is normal, if leaves are dropping but no new ones are growing in to replace them, it is a sign that something is wrong. If Black walnut receiving inadequate light does manage to grow, the new growth is often spindly, pale, and prone to insect infestation. Paying attention to these signs and changing the lighting conditions of the plant will make a significant difference.

Does Black walnut need special care about sunlight during its different growth stages?

Tender, new leaves are especially sensitive to sunburn. Bearing this in mind, very young Black walnut and when it's in a strong growth phase, such as in late spring and early summer, will be more sensitive to harsh sun and heat than the mature one or those in a more dormant fall growth stage. Black walnut fresh from a nursery is also usually not prepared for strong full sunlight and must be introduced to it slowly.

Are there any cautions or tips for sunlight and Black walnut?

Recently transplanted Black walnut will often experience a bit of shock and will need to be cared for carefully, either shaded from bright afternoon sun or placed in a protected area. On very hot days, you may see the leaves of Black walnut drooping—this is usually nothing to worry about. Plants will send the water in their leaves down into their roots to protect them from burning. However, if the leaves are still drooping in the evening or the next morning, the plant needs water. Always avoid watering during the hottest times of day, as sunlight can hit wet leaves and scorch them easily.

Black walnut that has been underwatered will be weaker than that with consistently moist soil. This can leave it with weak roots that are unable to protect the leaves on hot, sunny summer days by diverting water away from the leaves. Care for an underwatered plant by giving it a long, deep watering and then allowing the top two inches of soil to dry out before the next watering. Even if it loses its leaves, if cared for properly it will grow new ones.

What is the optimal temperature for Black walnut?

The best temperature for Black walnut to thrive is 65~80℉(18~27℃). During the primary growing phase, the highest temperature tolerable would be 95℉(35℃), while the lowest tolerable temperature would be 15℉(-10℃). This species is tolerant of low temperatures and will survive freezing winters. The perfect, highest, and lowest temperature range:

Perfect：65~80℉(18~27℃)

Highest：85~95℉(30~35℃)

Lowest：-5~15℉(-20~-10℃) or below

Should I adjust the temperature for Black walnut during different growing phases?

Research shows that Black walnut will begin to exhibit signs of stunted growth during prolonged periods of higher temperatures, especially during the development of axillary buds and the growth of main shoots. Keeping the temperatures consistent and cooler, around 65℉(18℃), will encourage vigorous growth after germination or transplanting.

How can I keep Black walnut warm in cold seasons?

Black walnut can withstand freezing temperatures when planted in the ground in areas that don’t get below of 15℉(-10℃) as an extreme temperature during the winter months. But if planted in pots or containers, then their roots must be protected from the winter cold. Do this by wrapping the container in a blanket or bringing it inside where it will be fully protected from the elements.

What damage will Black walnut suffer if the temperature is too high/low?

Greater harm will come to Black walnut if the temperature is consistently too high versus too low.

If Black walnut gets too hot, seed germination and photosynthesis efficiency is lessened due to hormone triggers caused by heat stress. The plant will show signs through wilting, leaf browning, and potentially death.

If Black walnut gets too cold, plant functions such as nutrient uptake and photosynthesis will cease, resulting in the possible death of the plant. If a single freezing event occurs during the growing season, then a membrane phase transition might occur, which can cause a cease in plant functions and death of the plant.

What tips and cautions should I keep in mind when it comes to temperature for Black walnut?

Keeping the soil temperature consistent is one of the most important strategies to keeping Black walnut healthy, which leads to successful budding, flowering, and new growth. Do this by consistently watering, adding mulch to bare soil, and planting in the shade.

How can I keep Black walnut warm without a heat pad?

Due to the cold tolerance of Black walnut, heating pads will not be necessary if planted outside in the ground. If the plant is in an outdoor pot, then bring it inside a heated house and place it in a sunny window during the winter months.

How can I provide Black walnut with an adequate temperature condition?

To ensure adequate temperature conditions are present, plant Black walnut in an area with partial shade. If possible, use afternoon shade to provide the best protection during the hottest part of the day. This will also result in lower temperatures in the soil due to increased moisture retention. If Black walnut is planted indoors, then keep the container away from windows and out of direct sunlight during the summer months to prevent the soil temperature from spiking daily.

How can I save Black walnut from temperature damage?

During the summer or times of high heat, give Black walnut extra shade and water to help cool its leaves, roots, and soil. During cold snaps or growing season freezes, cover sensitive budding vegetation with frost cloth or water using sprinkler systems. If it’s only nearing freezing temperatures for a short period, then water during the day several hours before the freeze. If the temperature is predicted to remain below freezing for an extended period, then keep the sprinkler running until the temperature rises above freezing the following day.

Should I adjust the temperature for Black walnut in different seasons?

Black walnut is a mid-temperature plant that can easily tolerate the typical fluctuations of the seasons and remain a hardy species when planted in maintained landscapes areas, containers, or indoors. Therefore, adjusting the temperature during the different seasons is unnecessary for primary growth. If flowering is stunted or impeded, then allowing the plant to experience a season of winter freeze could help to revive flowering.

Under what conditions should I stop adjusting the temperature for Black walnut?

If it becomes too difficult to lower the temperature for an indoor plant during the summer, then plant it outside in the ground or in a container. Make sure to plant Black walnut in a shaded location and water often to keep the soil moist.

Why do I need to fertilize my Black walnut?

Regardless of which kind of Black walnut you own, regular fertilization will help you grow a plant that has great overall health. The proper supply of nutrients leads to more vigorous growth and can help your Black walnut be more resilient to tough growing conditions while also gaining a better ability to fight off diseases and pests.

The foliage of your Black walnut is one of its most attractive features, which is why you should do all you can to keep it intact. Again, this means creating and adhering to a regular fertilization schedule that is specific to your Black walnut. Doing so will prompt your Black walnut to develop leaves with a deep color and a lush overall look.

When is the best time to fertilize my Black walnut?

The first time that you should fertilize your Black walnut is during the late winter or early spring. This type of fertilization gives your Black walnut all the nutrients it needs to resume healthy growth once the weather gets warm enough.

It is also beneficial to many Black walnut to provide an additional fertilizer feeding during early fall if you in a warm climate region. Fertilizing in early fall not only adds additional nutrients to the soil, which your Black walnut will use in the following growing season, but it also helps your Black walnut be a bit more hardy and capable of surviving the winter cold without experiencing foliage damage. Earlier fertilisation will ensure that the new branches have enough time to grow to withstand the cold winter.

When should I avoid fertilizing my Black walnut?

There are a few times during the year when you should not fertilize your Black walnut. The first time occurs during the early and mid-winter months, during which time your Black walnut will be dormant and in no need of feeding.

It is also unwise to fertilize this plant during the late spring and all of the summer. During that time of year, the weather will likely be hotter and can be much dryer as well. Both conditions make it more likely that your Black walnut will have a very negative response to fertilization. To avoid such issues, stick to a fertilization schedule that involves feeding exclusively during early spring and early fall.

What type of fertilizer does my Black walnut need?

In most cases, the most important nutrient for a Black walnut is nitrogen, but that does not mean that phosphorus and potassium are unimportant. On the contrary, your Black walnut likely needs a decent amount of all three main nutrients, which is why a balanced fertilizer, such as a 10-10-10, can work well.

However, a more nuanced ratio of nutrients often leads to optimal growth for a Black walnut. Often, fertilizers that are a bit higher in nitrogen work a bit better. For example, a ratio of 10-6-4 can often work well. When fertilizing, you can use a granular fertilizer or a liquid-based one.

How do I fertilize my Black walnut?

To fertilize your Black walnut using a granular fertilizer, all you need to do is sprinkle the fertilizer on the soil at the correct time. The slow-release nature of granular fertilizer will release nutrients into the soil slowly over time. As is usually the case, it's best to water your Black walnut, at least lightly, before applying fertilizer.

As an alternative, you can use a liquid fertilizer, but this is less common. To use this approach, mix your fertilizer with water, then pour the water onto the soil around the base of your Black walnut. At times, it is beneficial to perform a soil test before fertilizing to see if you will need to alter the pH at all.

What happens if I fertilize my Black walnut too much?

Overfertilization is always a risk when you are feeding a Black walnut. Overfertilization is especially likely if you feed this plant at the wrong time of year, feed it too often, or feed it without watering the soil first.

When overfertilization takes place, your Black walnut may begin to develop brown leaves. Your Black walnut can also show stunted growth in some cases. On the other hand, it is also possible that too much fertilizer can prompt your Black walnut to rapidly produce too much new growth, much of which will be weak and prone to breaking. Weak new wood can also detract from the overall form and structure of your Black walnut.

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Explore 6 of plant how-tos on Toxic, Feng shui direction, Water, Lighting, Temperature, etc.

Toxic

Slightly Toxic to Humans

Black walnut is a tree with toxic properties that may harm humans if it's touched or eaten. The toxic effects are usually mild. While all parts of the tree contain the potentially toxic substance known as juglone, the most toxic part is the husks of the fruits. Symptoms of touching the jugalone are skin irritation and welts, while ingesting this substance can lead to negative reactions in humans. When dealing with the tree or handling nearby plants which might have been coated in juglone, be sure to wear gloves to avoid skin irritation.

Feng shui direction

East

Black walnut can be compatible with East-facing environments, as it is believed to symbolize stability and growth. The robust nature of this plant may attract positive energy and create an atmosphere of nourishment and balance, making it a suitable addition to enhance the surrounding Chi.

Water

Every 1-2 weeks

Black walnut, or Juglans nigra, is native to North America's eastern hardwood forests, specifically favoring areas with deep, fertile, moist, well-drained soils. These lands receive on average 30 to 60 inches of precipitation annually; hence, black walnut thrives under frequent and copious watering. The species tolerates humid conditions due to prevalence of such conditions in its native habitats. Watering your black walnut tree should thus lean toward a more generous approach while being watchful for drainage quality.

Lighting

Full sun

Black walnut has a profound affinity for continual exposure to sun rays, yet can manage with somewhat limited light. It thrives in unplentiful light conditions, reflecting its earliest growth setting. Too much or too little sun can disrupt the plant's overall growth and vitality.

Temperature

-25 41 ℃

In its native growth environment, black walnut prefers a mild climate with temperatures ranging from 5 to 35 ℃ (41 to 95 ℉). During the growing season, it thrives in warm temperatures and ample moisture. For optimal growth, it should be planted in well-draining soil where it can receive full sun. In cooler months, it can withstand temperatures as low as -20 ℃ (-4 ℉).

Transplant

40-70 feet

For successful transplanting, the ideal season for black walnut is between late spring to mid-summer, as warmer temperatures encourage root establishment. Choose a sunny location with well-draining soil to optimize growth. A friendly tip: Avoid transplanting near other plants, as black walnut may inhibit their growth.

Beeches, walnuts, and allied trees

Common Pests & Diseases

Common issues for Black walnut based on 10 million real cases

Leaf beetles

Leaf beetles are a class of colored insects 1 to 2 cm in size. They gnaw on leaves and petals resulting in small, round holes scattered over the surface.

Solutions: For less serious cases: Remove beetles, nymphs, and eggs. Remove all life stages of the beetles and kill them by placing them in a bucket of warm, soapy water. This can be done more easily by placing the bucket under affected leaves and shaking the plant. This method is most effective in the afternoon when leaf beetles are more active. Always dispose of insects in a sealed bag or container to avoid escape and spread. To treat more serious infestations: Apply organic insecticides. Use naturally-derived insecticides before moving on to synthetic insecticides. Neem oil and pyrethrum are naturally-derived insecticides that should be applied following label instructions. Apply synthetic insecticides. Examples of insecticides effective for leaf beetles include carbaryl, permethrin, and bifenthrin. Apply insecticides according to label instructions.

Fruit Spot

Pathogenic infections can cause spots (typically black or brown) to appear on the fruit.

Solutions: Prune regularly - prune as a preventative measure as well as to remove any plants and plant parts affected by fruit Spot. Improve air circulation and drainage Fertilize as needed Spray applications - there are few programs that are effective at controlling fruit Spot for home growers, but the local cooperative extension may be able to provide information regarding potential chemical treatments if the disease is severe.

Fruit withering

Fungal infection or normal ripening can cause the fruit to dry out.

Solutions: There are a number of appropriate solutions to control fruit withering: Remove any fruit as soon as it shows any signs of infection. Do not compost. Use a fungicide prior to leaf bud and then as per manufacturers instructions throughout the season.

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.

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.

Underwatering

A lack of water will cause the leaves to gradually turn yellow starting at the base of the branch while the entire plant appears to wilt.

Solutions: Your plant is very thirsty and needs water promptly. You can revive your plant by giving it water. The easiest technique is to slowly pour water into your plant’s soil so that the whole surface is moistened. If you pour the water too quickly, the water will flow directly through rather than diffusing throughout the soil. If your plant’s pot does not have drainage holes, do not give your plant more than about a third of the pot’s volume of water. If your plant’s pot does have drainage holes, you can add water slowly until the soil is thoroughly moistened and the water flows freely through the pot. If you trim off yellow leaves to improve the plant’s appearance, do not remove more than a third of the plant’s leaves. It may be better to wait until leaves have died and fallen off to remove them.

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Toxicity

* The judgment on toxicity and danger is for reference only. We DO NOT GUARANTEE any accuracy of such judgment. Therefore, you SHALL NOT rely on such judgment. It is IMPORTANT TO SEEK PROFESSIONAL ADVICE in advance when necessary.

Slightly Toxic to Humans

Toxic to Dogs

The black walnut can cause severe poisoning in dogs that eat it; it is important to contact a veterinarian quickly. Fallen nuts that have started to mold can cause symptoms that include tremors and seizures. Some studies have shown that eating wood from the black walnut tree can also cause poisoning in dogs, causing panting, restlessness, and vomiting.

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Distribution Map

Habitat

Woods, hillsides

Native

Cultivated

Invasive

Potentially invasive

Exotic

No species reported

More Info

Plant Type

Tree

Flower Color

Green

Yellow

Bloom Time

Mid spring, Late spring, Early summer

Leaf Color

Green

Name story

Black walnut

Walnut is actually derived from "walhnutu" from the Anglo-Saxon language meaning "foreign nut", as the nut originated from Italy and Gaul. Juglans nigra is called black walnut to differentiate itself from the indigenous nut, hazelnut. Also, its tree bark is greyish-black in color and its wood is dark-colored by nature. Hence, it is called the black walnut.

Symbolism

Health, Mental powers, Infertility, intelligence, focus, clarity of thought

Usages

Garden Use

Black walnut is a beautiful enough tree to have earned an Award of Garden Merit. It is commonly grown commercially, in large public parks or very big yards (it usually grows to around 30 m tall), as it provides excellent shade; but is too big for urban areas. Black walnut is usually planted as a standalone specimen due to the toxicity of falling fruits that can harm other plants, but trees like the sugar maple and flowering dogwood work well with it.

Scientific Classification

Phylum

Vascular plants

Class

Dicotyledons

Order

Family

Walnut

Genus

Walnuts

Species

Black walnut

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