Are you interested in growing your own medicinal plants?
Milk thistle, a plant with a rich history of medicinal use, might be just the plant for you.
Not only is it easy to grow, but it also adds a unique touch to any garden with its large, dark green, hairless leaves marbled with white.
However, milk thistle can be invasive if not properly managed.
In this article, we will guide you through the process of growing milk thistle both indoors and outdoors, as well as provide tips on how to care for it and harvest its seeds.
Let’s get started!
How To Grow Milk Thistle?
There are two ways to grow milk thistle: direct seeding and starting seeds indoors.
If you choose to direct seed, spread the seeds over the desired area in either early spring or late fall. Milk thistle seeds only take two weeks to germinate, and it is recommended to space the plants 12-15 inches apart.
Alternatively, you can start the seeds indoors in containers such as biodegradable cells or deep plastic cells in February or March. Plant the seeds about 1/4 inch deep in organic seed starting mix and maintain lightly damp soil (not wet) and temperatures around 70°F until the seeds have germinated.
After germination, your milk thistle seedlings will need direct sunlight. You can either leave them outdoors any time temperatures are above frost/freezing and bring them indoors any time temperatures go below frost/freezing or keep them indoors under grow lights.
Transplant your milk thistle seedlings outdoors as soon as your last frost date has passed to prevent their long tap roots from getting too wrapped around in the seedling cells. The final spacing for the plants should be 24-36 inches in rows 3 feet apart as they grow quickly to a large size.
Introduction To Milk Thistle
Milk thistle (Silybum marianum L. Gaertn.) is a plant that has been extensively studied for its therapeutic properties, particularly in treating liver disease. The plant contains silymarin, a mixture of three flavonolignans that provide its medicinal benefits. Milk thistle is a biennial plant that can be grown successfully on a range of soil types, from sandy soils to heavier clay soils.
There are two ways to grow milk thistle: direct seeding and starting seeds indoors. If you choose to direct seed, spread the seeds over the desired area in either early spring or late fall, spacing the plants 12-15 inches apart. Milk thistle seeds only take two weeks to germinate. Alternatively, you can start the seeds indoors in containers such as biodegradable cells or deep plastic cells in February or March.
Milk thistle is a prickly plant that grows in clumps, so it is important to wear gloves when thinning or hand-weeding. The plant is very adaptable to growing conditions, provided the soil is well-drained. Nutrient requirements of this crop are low to moderate since it is adapted to poor quality soils and many different growing conditions.
Milk thistle can be harvested for young plants for salads or steaming, but the spines need to be removed. The seeds are harvested in the fall from the drying flower heads on the plant. Overall, milk thistle is a valuable plant to grow for its medicinal benefits and adaptability to various growing conditions.
Choosing The Right Location For Milk Thistle
Choosing the right location for milk thistle is crucial for its growth and development. Milk thistle is a hardy plant that can grow in almost any type of soil, but it prefers dry, well-drained soil in full sun. It is found along roadsides, in fields, and waste places.
If you are growing milk thistle in your garden, choose a spot that receives full sun. However, partial shade is also tolerable for milk thistle. The plant can grow up to four feet tall, so make sure to choose a location with enough space for the plant to grow.
Milk thistle is drought-resistant and does not require much watering. Standard natural rainfall will suffice in all but desert regions. Light watering during seed germination can help, but it should cease when seedlings break the soil surface. Indoor seedlings should be treated as cacti and watered lightly once a week.
Milk thistle is very adaptable and can grow in almost any type of soil. It grows well on compacted clay soils, but a smidgen of high nitrogen fertilizer as well compost or dry manure is advisable. A thin layer of organic mulch wouldn’t hurt either.
Milk thistle has very few disease and pest problems. Occasionally some beetles may appear, but they are not a major concern. However, it is toxic to some livestock, not because of its inherent compounds which are harmless to people, but because of the interactions of these compounds – in particular potassium nitrate – with bacteria in the stomachs of sheep and cattle that will set off a chain reaction that leads to oxygen deprivation.
How To Plant Milk Thistle
To plant milk thistle, you can either direct seed or start seeds indoors. If you choose to direct seed, spread the seeds over the desired area in either early spring or late fall. It is recommended to space the plants 12-15 inches apart.
If you prefer to start seeds indoors, use starter trays and cover the seed about 1/4 inch with soil. Keep the seeds moist for germination and maintain temperatures around 70°F until the seeds have germinated.
After germination, your milk thistle seedlings will need direct sunlight. You can either leave them outdoors any time temperatures are above frost/freezing and bring them indoors any time temperatures go below frost/freezing or keep them indoors under grow lights.
Transplant your milk thistle seedlings outdoors as soon as your last frost date has passed. The final spacing for the plants should be 24-36 inches in rows 3 feet apart as they grow quickly to a large size. It is important to thin the plants to the strongest one if you sowed multiple seeds in one spot.
Milk thistle is very adaptable to growing conditions, provided the soil is well-drained. Work the garden soil 6-8 inches in depth and add compost to improve the soil before planting. Milk thistle is a biennial plant that can grow up to 54 inches tall, so make sure to give it enough space to grow.
Harvest young plants for salads or steaming, but be sure to remove the spines. The seeds are harvested in the fall from the drying flower heads on the plant. One plant can produce over 6,000 seeds that can remain viable for nine years and germinate at any temperature between 32 and 86 degrees F, so be mindful of its invasive potential and prevent it from spreading to neighboring land.
Caring For Milk Thistle
Milk thistle is a hardy plant that requires minimal care once it is established. However, there are a few things you can do to ensure that your milk thistle plants thrive.
Firstly, milk thistle requires full sun to grow and flower. Therefore, it is important to plant them in a location that receives at least six hours of direct sunlight each day.
Secondly, milk thistle is very adaptable to growing conditions, provided the soil is well-drained. It is recommended to amend the soil with compost or well-rotted manure before planting to improve soil fertility and drainage.
Thirdly, milk thistle is a biennial plant, which means it produces leaves and stems in the first year and flowers and seeds in the second year. To encourage seed production, it is important to deadhead the spent flowers before they go to seed.
Lastly, milk thistle can be susceptible to pests such as aphids and spider mites. To prevent infestations, it is recommended to spray the plants with neem oil or insecticidal soap every two weeks.
Harvesting Milk Thistle Seeds
Harvesting milk thistle seeds is a simple process that can be done once the flowers have dried out and produced silvery-white seed heads known as pappus. This usually occurs in the fall, but it can vary depending on the location and climate.
To harvest the seeds, it’s important to wear thick gardening gloves due to the thorny nature of milk thistle leaves. Cut off the flower heads from the base of the stem and place them into a paper bag. Set the bag in a warm location for around five to seven days to allow the flower heads to completely dry out.
Once the flower heads have thoroughly dried, place them into a burlap sack and tumble the bag around. This will help to loosen the seeds from the flower heads. Then, chop the flower heads to remove the seeds and winnow them in the open air.
To winnow, pour the seeds from the burlap sack into a bucket placed on the ground outdoors or held with one arm. As you pour the seeds into the bucket, any unwanted chaff should blow away. If any chaff lands in the bucket, remove it and discard it.
Finally, store the milk thistle seeds in an airtight container in a cool, dark place until you’re ready to use them. Milk thistle seeds can be used for tea or as a supplement for various health benefits. By following these simple steps, you can easily harvest your own milk thistle seeds for personal use.
Common Pests And Diseases Of Milk Thistle
Milk thistle is a hardy plant that is not bothered by many pests, and no diseases have been noted. However, some beetles may occasionally appear, but they are not a major concern.
It is important to note that milk thistle is toxic to some livestock, not because of its inherent compounds which are harmless to people, but because of the interactions of these compounds – in particular potassium nitrate – with bacteria in the stomachs of sheep and cattle. This can lead to oxygen deprivation, so it is important to keep livestock away from milk thistle plants.
Additionally, milk thistle is an invasive species in some states and can quickly infest disturbed landscapes such as roadsides, trails, natural areas, pastures, forest and field margins, mining locations, waste areas, and unmaintained gravel pits. To prevent the spread of milk thistle beyond your garden, it is recommended to wear gloves when thinning or hand-weeding and to harvest the seeds before they dry out and spread.
