A popular vegetable crop in the south of the U.S., collard greens are actually native to Asia Minor and the eastern parts of the Mediterranean. A member of the Brassicaceae or Cruciferous vegetable family, these low maintenance, no fuss crops thrive in most USDA Zones and climates.
Like kale, these leafy vegetables are best described as non-head forming cabbages. Grown predominantly for their leaves, which can be cooked like kale leaves, these two common vegetable garden crops share many genetic similarities. But that is where the similarities end. Collard greens have their own, unique flavor and texture. This distinct flavor has helped to make the plants a popular member of the vegetable family.
As well as their distinct flavor, the appearance of the plant has helped to cement its popularity. Collards’ large, smooth foliage can seem almost waxy in appearance. However, upon closer inspection you will notice pronounced veins running across the leaves.
When harvested the foliage has a strong, distinct, almost bitter flavor. Meanwhile, the stems are fibrous and tough. Like other members of the cruciferous family, collard greens produce small typically yellow flowers in the shape of a cross. These dainty blooms are also edible, with a sweet cabbage-like flavor.
If you want to add collard greens to your vegetable garden, this is your complete guide.
A staple of the southern states, these leafy vegetables are suitable for a range of planting conditions.
Different Varieties of Collard Greens
The plants are typically grouped by their growing characteristics into either loose leaf or loose head varieties. Loose head varieties are a good option if you want to harvest the entire plant at once. If you would rather a cut and come again plant, supplying a steady stream of edible foliage, plant a loose leaf variety.
Many of the more common or traditional varieties, such as Georgia and Vates produce loose, open plants. Newer, hybrid varieties such as Morris Heading have a quicker growth habit than traditional cultivars. They also tend to curve in on themselves, forming a loose head and more compact plant.
Some of the most common varieties include:
- Vates, a smooth leaf, compact variety that matures in 75 days.
- Georgia, a larger plant than Vates but it also matures in 75 days. It produces larger, tender waxy foliage. It is also heat tolerant and slow to bolt.
- Champion is a compact Vates hybrid that is ideal for smaller spaces. Maturing within 60 days, its cabbage-like leaves store well.
- Flash is another small plant with a vigorous growth habit. Maturing in 55 days its foliage is smooth and sweet.
- Green Glaze matures within 75 days. It’s dark glossy green foliage is less likely to be damaged by caterpillars than other varieties.
Take the time to select a variety that is suitable for your garden.
Collard greens are easily grown from seed. You will find seed packets for sale online or in garden stores. If you don’t have the time or space to grow from seed, you can purchase young plants, known as nursery transplants, from garden stores and nurseries.
Where to Plant
These biennial vegetables are usually grown as annuals. Hardy in USDA Zones 6 to 11 they happily grow as an annual in most planting areas.
When fully mature, the plants can reach 20 to 36 inches in height and enjoy a spread of 24 to 36 inches. Make sure you plant them somewhere where they have lots of room to develop.
Collard greens thrive in full sun positions. They also grow in partial shade, but growth may not be as prolific. The soil should be slightly acidic. A pH level of 6.5 to 6.8 is ideal. If your soil is too alkaline, this article explains a number of different ways to make soil more acidic.
If you are growing your collard greens in raised beds or pots, select a deep container. The roots can grow to a depth of 2 ft. However, regular watering helps to reduce the need for plants to set extensive root systems. Fill the container with fresh potting soil before planting.
Prior to planting, loosen the soil and work in organic material. Scater a balanced, general purpose granular fertilizer evenly over the soil. Apply roughly one cup of granules per 10 ft of row. Rake the fertilizer in well.
Weed the soil and rake in amendments before sowing or planting.
How to Grow from Seed
Sow the seeds in early spring for an early summer harvest or in late summer for an early fall harvest. Most varieties require between 55 and 75 days of growing time before they are ready for harvest.
In USDA Zones 8 and higher the plants are at their tastiest when planted in the fall and harvested throughout the winter. Growing later in the year helps to avoid issues such as bold. Additionally, exposure to cool weather and light frosts helps to sweeten a number of cooking greens such as collards.
You can sow the seeds either directly into their final position or start them off undercover before transplanting outside.
Sow the seeds in a prepared site about 2 weeks before the last predicted spring, frost date. When planting or sowing seeds, the soil temperature should be over 45 ℉. Don’t worry about unexpected late season frosts. Even small seedlings can cope surprisingly well with light frosts and chilly spring weather. In the fall, sow the seeds at the height of mid summer, around 6 to 8 weeks before your first predicted fall frost date.
Sow the seeds a quarter to half an inch deep and cover with a light layer of soil. I like to moisten the soil before I sow my seeds. This helps them to stick in place. Following germination thin the seedlings out to a spacing of 6 to 8 inches.
For a slightly earlier harvest, start your seeds indoors 4 to 6 weeks before the last predicted frost date. Sow the seeds in pots or seed trays filled with fresh, potting soil. Sow as thinly as possible to a depth of about a quarter of an inch deep. Place the pots or trays in a light position, such as on a windowsill.
Seeds can be started in their final position or, for an earlier harvest, undercover.
Use a watering can with a fine spray to keep the soil evenly moist.
Following germination, allow the seeds to grow on for a few weeks. Transplant the seedlings into their final position once the last frost date has passed.
Planting out Collard Greens
To transplant, make a hole in the soil large enough to hold the seedling. Carefully remove the seedling from the container. You may need to squeeze the sides to loosen the soil, enabling you to easily remove the seedling. Be careful not to overly disturb or damage the root system. Plant the seedling to the same depth as when it was in the container. Cover with soil and water well.
Space transplants 18 to 24 inches apart. Seedlings started in the ground can also be spaced out as they grow and develop. Each row of collard greens should be spaced 30 inches apart.
Caring for Collard Greens
Once planted, collard greens care is minimal and straightforward.
Mulch the soil around the plants to suppress weed growth. When watering and working around the plants, try to keep the foliage as clean as possible. This helps to prevent disease.
These are cool season vegetables and will bolt, or go to seed, when the weather warms up. Mulching and regularly watering helps to keep the plants cool and delays bolting.
When to Water
Keep the plants well watered. In general the plants need one to one and a half inches of water a week. Don’t allow the soil to dry out.
Fertilizing Collard Greens
These are not heavy feeding plants. Apply a balanced, slow release fertilizer once every 4 to 6 weeks. Alternatively, side dress the plants with a composted manure. Fertilizing helps the plants to thrive and continue producing foliage despite repeated harvests.
Cold Weather Protection
Collard greens tolerate light frosts. However, they will require a little protection if you want them to survive colder temperatures. While this is not normally a problem if you are growing in the spring, you may need to cover fall crops with a floating row cover or horticultural fleece. Alpurple Winter Plant Covers are made of breathable fabrics, meaning that your crops can still absorb light and moisture while enjoying protection from cold winter frosts. Protecting the crops in this way enables you to continue harvesting fresh collard greens well into the winter months.
Chamomile is a popular collard greens companion plant. Aromatic herbs such as thyme are also great companion plants. These help to deter pests such as cabbage worms. Clover is also a popular interplanting choice because it helps to deter pests such as aphids.
When planted in close proximity collard greens can also help to improve the flavor of both onions and cabbages. A pleasingly versatile member of the vegetable garden, collard greens are also good companions for:
Attractive herbs such as chamomile make great companion plants.
Avoid planting near strawberries and rue. These are not good companion plants, often stunting each other’s growth and impairing fruit or foliage production.
Collecting and Saving Seeds
While seeds are easily available, you can also harvest your own. To do this, allow the plants to remain in the ground over winter. These are biennial plants, usually flowering in their second year. As the flowers fade, seed pods emerge.
Allow the pods to harden and dry out on the stem. When the pods turn brown and brittle, cut them away from the plant. Gently break the pods and remove the seeds. Ripe seeds will be black. Store the seeds in an airtight tin until you are ready to use them.
Common Collard Greens Problems
These leafy greens are one of the most resilient plants in the vegetable garden. They can be affected by the same pests and diseases as many other members of the cabbage family.
Regularly check the foliage for insects such as flea beetles, slugs, cabbage root maggots, aphids, cabbage loopers and cabbage worms. A homemade insecticidal soap or citrus oil can be used to control infestations. Persistent infestations may require repeat treatments before the problem is fully cured.
Common diseases include clubroot, black rot and blackleg. Most of these issues can be prevented by properly caring for your plants. Make sure when planting to correctly space them out, so that air can flow freely between the plants, and try not to overwater or plant in waterlogged soil. Adopting a simple form of crop rotation, so that you are growing in fresh soil every year, also helps to prevent disease.
How to Harvest
As the foliage develops and matures, harvest the leaves regularly. Cut from the outside of the plant in. Mature leaves are smooth and firm. Tender young foliage is less likely to be as bitter as more mature leaves. Regularly harvesting encourages more foliage to form.
To harvest use a sharp knife or scissors to cut away the leaves. Start with the outer foliage and work towards the center of the plant.
If you choose to harvest the entire plant while it is young, the crown should resprout for another harvest. Wait until the plant is at least 6 inches tall before completely harvesting.
Store the foliage in a damp paper towel. This helps to keep the leaves fresh for around 4 days. Try not to store the foliage for too long, this can cause it to become bitter and unpleasant. It is better to harvest what you need and no more.
Collard greens are versatile leaves. They can be boiled, braised, steamed or sauteed.
To make the most of the plant’s distinctive flavor, the foliage is best cut as and when you need it.
A popular vegetable in the southern states, collard greens are a versatile, easy to grow crop that suits a range of planting zones. Easy to care for and pleasingly resilient, these hardy leaves bring their own distinct flavor and appearance to a vegetable garden. They are also packed full of nutritious vitamins, particularly vitamins A, and C. With all this in mind, why not grow some collard greens in your garden?
Jen is a master gardener, interior designer and home improvement expert. She has completed many home improvement, decor and remodeling projects with her family over the past 10 years on their 4,500 sf Victorian house. She is also a passionate farmer who keeps goats, chickens, turkeys cows and pigs on her farm, and an instructor for her community’s Organic and Sustainable Farming project.