Blessed thistle (Centaurea benedicta) Flower, Leaf, Care, Uses

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Blessed thistle

Centaurea benedicta

The spiny blessed thistle is considered a noxious weed in many areas. This Eurasian native's tough, invasive nature has helped it spread about much of the globe. It grows in open areas like meadows and fields and is quick to colonize disturbed soils, making it a common sight around roads and construction grounds. Blessed thistle has featured in Shakespeare's play, Much Ado About Nothing.

Hardiness Zones

5 to 9

More Info

Plant Type

Herb

Flower Color

Yellow

Scientific Classification

Phylum

Vascular plants

Class

Dicotyledons

Order

Asters bellflowers fanflowers and allies

Family

Daisy

Genus

Centaury

Species

Blessed thistle

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Distribution Map

Habitat

Roadsides, fields, waste places, cultivated land

Native

Cultivated

Invasive

Potentially invasive

Exotic

No species reported

Questions About Blessed thistle

Watering

Sunlight

Temperature

What is the best way to water my Blessed thistle?

To water Blessed thistle, you can use a garden hose with a spray nozzle, a watering can, or just about any other common watering tool. Generally, Blessed thistle is not too picky about how they receive their water, as they can live off of rainwater, tap water, or filtered water. Often, you should try not to water this plant from overhead, as doing so can damage the leaves and flowers and may lead to disease as well. At times, the best method for watering this plant is to set up a drip irrigation system. These systems work well for Blessed thistle as they apply water evenly and directly to the soil. For one Blessed thistle that grows in a container, you can use a similar watering approach while changing the tools you use. To water a container-grown Blessed thistle, use a cup, watering can, or your tap to apply water directly to the soil.

What should I do if I water my Blessed thistle too much or too little?

The remedy for underwatering Blessed thistle is somewhat obvious. When you notice that your plant lacks moisture, simply begin watering it on a more regular basis. The issue of overwatering can be a much more dire situation, especially if you fail to notice it early. When your Blessed thistle is overwatered, it may contract diseases that lead to its decline and death. The best way to prevent this outcome is to choose a proper growing location, one that receives plenty of sunlight to help dry the soil and has good enough drainage to allow excess water to drain rather than pooling and causing waterlogged soils. If you overwater your Blessed thistle that lives in a pot, you may need to consider changing it to a new pot. Your previous container may not have contained soil with good drainage or may not have had sufficient drainage holes. As you repot your overwatered Blessed thistle, make sure to add loose soils and to use a pot that drains efficiently.

How often should I water my Blessed thistle?

Blessed thistle needs water regularly throughout the growing season. Beginning in spring, you should plan to water this plant about once per week. As the season presses on and grows warmer, you may need to increase your watering rate to about two to three times per week. Exceeding at this rate can be detrimental to your Blessed thistle. With that said, you should also ensure that the soil in which your Blessed thistle grows remains relatively moist but not wet, regardless of how often you must water to make that the case. Watering Blessed thistle that lives in a pot is a bit different. Generally, you'll need to increase your watering frequency, as the soil in a pot can heat up and dry out a bit faster than ground soil. As such, you should plan to water a container-grown Blessed thistle a few times per week in most cases, versus just once per week for an in-ground plant.

How much water does my Blessed thistle need?

There are a few different ways you can go about determining how much water to give to your Blessed thistle. Some gardeners choose to pick their water volume based on feeling the soil for moisture. That method suggests that you should water until you feel that the first six inches of soil have become moist. Alternatively, you can use a set measurement to determine how much to water your Blessed thistle. Typically, you should give your Blessed thistle about two gallons of water per week, depending on how hot it is and how quickly the soil becomes dry. However, following strict guidelines like that can lead to overwatering if your plant requires less than two gallons per week for whatever reason. When growing Blessed thistle in a container, you will need to use a different method to determine how much water to supply. Typically, you should give enough water to moisten all of the layers of soil that have become dry. To test if that is the case, you can simply stick your finger in the soil to feel for moisture. You can also water the soil until you notice a slight trickle of excess water exiting the drainage holes of your pot.

How can I tell if i'm watering my Blessed thistle enough?

It can be somewhat difficult to avoid overwatering your Blessed thistle. On the one hand, these plants have relatively deep roots that require you to moisten the soil weekly. On the other hand, Blessed thistle are plants that are incredibly susceptible to root rot. Along with root rot, your Blessed thistle may also experience browning as a result of overwatering. Underwatering is far less likely for your Blessed thistle as these plants can survive for a while in the absence of supplemental watering. However, if you go too long without giving this plant water, it will likely begin to wilt. You may also notice dry leaves.

How should I water my Blessed thistle through the seasons?

You can expect your Blessed thistle’s water needs to increase as the season moves on. During spring, you should water about once per week. Then, as the summer heat arrives, you will likely need to give a bit more water to your Blessed thistle, at times increasing to about three times per week. This is especially true of Blessed thistle that grow in containers, as the soil in a container is far more likely to dry out faster than ground soil when the weather is warm. In autumn, while your Blessed thistle is still in bloom, it may need a bit less water as the temperature has likely declined, and the sun is no longer as strong as it was in summer.

How should I water my Blessed thistle at different growth stages?

Blessed thistle will move through several different growth stages throughout the year, some of which may require more water than others. For example, you will probably start your Blessed thistle as a seed. While the seed germinates, you should plant to give more water than your Blessed thistle will need later in life, watering often enough to maintain consistent soil moisture. After a few weeks, your Blessed thistle will grow above the soil and may need slightly less water than at the seedling phase. Then, once this plant is mature, you can begin to use the regular watering frequency of about once per week. As flower development takes place, you may need to give slightly more water to aid the process.

What's the difference between watering Blessed thistle indoors and outdoors?

There are several reasons why most Blessed thistle grow outdoors rather than indoors. The first is that these plants typically grow to tall. The second reason is that Blessed thistle needs more daily sunlight than most indoor growing locations can provide. If you are able to provide a suitable indoor growing location, you may find that you need to give your Blessed thistle water a bit more often than you would in an outdoor growing location. Part of the reason for this is that indoor growing locations tend to be a lot drier than outdoor ones due to HVAC units. The other reason for this is that soil in containers can dry out relatively quickly as well compared to soil in the ground.

How much sunlight should Blessed thistle get per day to grow healthily?

You must expose the plants to at least 6 to 8 hours of sunlight daily. They prefer more exposure to the morning light, especially in the summer. The Blessed thistle needs full sun and more sunlight that it can get. The more light these species get, the more they can manufacture food, produce beautiful blooms, and survive.

What type of sunlight does Blessed thistle need?

The Blessed thistle grows best under full sunlight. It's best not to crowd them together so they can get exposure to the sun evenly. The leaves shouldn't be starved with sunlight. If planted in pots, try to expose the herbaceous flowers in windows with direct sun and ensure they receive full sunlight regardless of the months.

They don't tend to do well in partial or filtered light as this will not produce strong stems and healthy flowers. It's best if the Blessed thistle is always exposed to the sun.

Can sunlight hurt plants? How to protect Blessed thistle from sun and heat damage?

When the temperature rises above 90℉(32℃), the Blessed thistle can get damaged by extreme temperatures, especially if they are exposed to many hours of sun. It's always ideal for providing some shade from the light in the afternoon in the summer. It's always important to keep in mind that the sunlight in the summer is stronger than the one in the winter. Sunlight exposure is also 50% longer in the summer than in the winter.

If the Blessed thistle is too stressed with sunlight, you might want to keep them fully hydrated. Water them when the top of the soil is about 2 inches dry, and move the plants indoors if it's too hot outside. This is the case if they are planted in containers.

It can be normal for the plant leaves to wilt during the day. Generally, they can recover at night. However, when you notice that the Blessed thistle is still drooping, this means that the plant is losing water fast, and you need to water them.

Should I protect Blessed thistle from sun exposure?

The Blessed thistle does not need any protection from the sun. In fact, they love the sun, and some species are heliotropic. Plant them in south-facing gardens whenever possible so they can be exposed from morning to afternoon. While the sun can benefit them, some may experience a sunburn. You might offer protection from the afternoon and midday sun through a shade of a tree or a wall.

Growing the Blessed thistle in shady areas is impossible because the larger flowers would require a lot of energy to grow and produce. Always provide the lighting conditions and set them in an area with full sun for best results.

What will happen if Blessed thistle gets inadequate sunlight?

When the Blessed thistle does not get adequate sunlight, or they are not placed in full sun locations, it's worth noting that the photosynthetic process will slow down. A lack of sunlight will cause the stems to become more leggy since they become thin and long since they tend to seek too much sunlight. They will not bloom and produce seeds in the shade.

Inadequate sunlight will also mean that the older leaves can die, the color of the new ones is lighter than the old foliage, and the new growth is smaller than the last ones.

The Blessed thistle indeed loves the sun so much. However, they can wilt when exposed to excessive heat and ultraviolet light during the extreme summer months, so be careful. You might want to cover them with a net that has a green shade, especially in the summer, to prevent the leaves and the flowers from scorching. When they are indoors, reduce the heat with the help of a fan.

Does Blessed thistle need special care about sunlight during its different growth stages?

When the Blessed thistle is growing, they need more light than their mature counterparts. The younger ones should receive adequate light, but they might not be prepared for sudden full sunlight, especially if they are grown in a nursery. They can be more sensitive to the summer sun, so the lighting should be gradual and slow.

How much light does Blessed thistle need for photosynthesis?

During summer or late spring, the Blessed thistle needs 6 to 8 hours of direct light every single day. This is whether they are planted outdoors. If the Blessed thistle is planted in pots or you're growing them in the winter, they need direct fluorescent lights that help them grow better. Make sure to place them in an indoor area where they are facing south or east so they can have enough sunlight for photosynthesis.

Are there any cautions or tips for sunlight and Blessed thistle?

When transplanting the plants, they should not be exposed to sudden sunlight. Give the Blessed thistle to grow and mature before transplanting outside. Some species of herbaceous plants can grow taller and might cast a shade on other young plants. Allow between 80 to 100 days of growing season before planting another batch to ensure that every plant receives more than enough sunlight for at least 6 hours a day.

Make sure that the Blessed thistle receives the best light possible, especially if it's planted in a nursery. These are sun-loving plants, but too much sunlight with a very hot temperature is also detrimental to their growth. Indoor lights should be replaced with natural sunlight as much as possible since these species crave this every day.

What is the optimal temperature for Blessed thistle?

The best temperature for Blessed thistle depends on the time of year. There are two primary seasons to discuss for temperature: the growing season, and the dormancy season. During the growing season, once Blessed thistle has begun to sprout, the ideal temperature range should be anywhere from 65~80℉(18~27℃). Any colder than 15℉(-10℃), and the plant will suffer; its leaves may brown and wilt, but if this is a short cold snap, then Blessed thistle may be able to survive with some help.

During the warmer parts of the year, Blessed thistle will need to be similarly protected from temperatures that are too high. 95-105℉ (35-40℃) is the top of this plant’s temperature range, and anything above that will compromise the integrity of the foliage and blooms of Blessed thistle. Hotter temperatures can cause wilting, drooping, and even sunburn on the leaves, which can be difficult for Blessed thistle to recover from. There are quite a few ways to combat this issue that are quick and easy!

Temperature requirements for first year or seedling Blessed thistle

If this is the first year of your Blessed thistle outside as a new plant, then it may need a little extra tending during the coldest months of the year. Not only can frost more severely damage a first-year Blessed thistle, but it can also prevent it from growing back as a healthy plant come spring. This plant needs to be kept at 40℉(5℃) or above when they’re not yet established, which can be done either by bringing your Blessed thistle inside for a month or two, or putting up mulch or fabric barriers that protect from frost damage.

It’s also a good idea to plant Blessed thistle in a shadier spot during the first year or two, as smaller and weaker plants have a more difficult time maintaining their own temperatures in the heat. First-year Blessed thistle should receive no more than five hours of direct sunlight per day, particularly if the ambient daytime temperature gets above 80℉(27℃). Shadecloth and frequent watering or misting are the keys to summer heat control.

How can I protect Blessed thistle from extreme temperatures?

If cold temperatures (below 15℉(-10℃)) do occur during the growing season, there are a few measures you can take to help protect Blessed thistle from frost or cold damage. If you’re growing Blessed thistle in a container, then the container can simply be brought inside in bright, indirect light until the temperatures rise up over the lower threshold again. Another option that’s better suited for ground-planted Blessed thistle is to use mulch or horticultural fabric to create an insulated barrier around the plant, which will protect the plant from frost and cold wind.

For temperatures that are hotter than 80℉(27℃) in the shade during the day, be careful to only expose Blessed thistle to six hours or less of sunlight per day, preferably in the morning hours. Putting up shade cloth, or a fine plastic mesh, can help reduce the amount of direct sunlight that hits the plant during the hottest parts of the day. You can also install a misting system that allows for a slow release of cooling mist around the base of the plant during the day to lower ground temperatures.

Dormant season temperature recommendations for Blessed thistle

During the cold winter months, Blessed thistle needs a certain measure of cold in order to stay in dormancy until it’s time to sprout. Sprouting too early, that is before the danger of the last frost has passed, can be fatal to Blessed thistle, especially if it’s already had a head start when the frost hits. Winter temperatures should ideally stay below 32℉(0℃), but if they get up to 40℉(5℃), everything will be just fine.

An unexpected warm spell during the cold months, which can happen in more temperate climates like woodland rainforests, can trigger a premature sprout from Blessed thistle. In this case, if there’s still imminent danger of frost, you may want to try covering it with clear plastic on stakes so that the cold has less of a chance of damaging the new sprout. This setup can be removed when the danger of frost has passed. Occasionally, Blessed thistle will be able to resprout at the correct time without any help, but this method increases the chances of a successful second sprouting.

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More About How-Tos

Water

Every week

Blessed thistle originates from regions with seasonal climates, preferring evenly moist soil. Ensure to water only when necessary to prevent overwatering, and always check soil moisture beforehand.

Learn More

Lighting

Full sun

Blessed thistle thrives under the intense and unfiltered rays of the sun. As this plant has evolved in environments with abundant solar exposure, an ample amount of light is vital for its health and optimum growth. Lack or excess of sunlight may cause stunted growth, pale coloration or wilting, disturbing its normal physiological processes.

Learn More

Temperature

-10 to 35 ℃

Blessed thistle is native to temperate regions and as such, thrives best in temperatures from 68 to 95 °F (20 to 35 ℃). It's well-adapted to warm climates, although seasonal temperature adjustments could be needed to fulfill its ideal growth conditions.

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Add to My Garden

Blessed thistle

Centaurea benedicta

Hardiness Zones

5 to 9