Collard Greens Plant Profile

collard greens growing

The Spruce / Autumn Wood

Collards are a member of the Brassicaceae family. They are grown for their leaves, which are cooked much like kale. This cooking green is most often associated with Southern U.S. cooking. Collard greens are native to the eastern Mediterranean and Asia Minor, but the plants are easily grown in most U.S. climates.

Like kale, collards are non-head forming cabbages. Collards and kale are quite similar genetically, but breeding and cultivating over the years has produced plants with different textures and flavor. Collard leaves are smooth and almost waxy, with pronounced veining. They are quite large, with a bright to dark green color, and the stems are very fibrous and tough. Collards also tend to have a stronger and more bitter flavor than kale. True to the cruciferous family, collard flowers have four yellow petals in the form of a cross. The flowers are edible and have a sweet, cabbage-like flavor.

Cooking greens are some of the most nutritious vegetables you can eat, and collard greens, in particular, are packed with vitamins A, C, and K; soluble fiber; calcium; folate; manganese; and tryptophan—and less than 50 calories per serving. Eating your collards even helps to lower your bad cholesterol.

Collards can be planted in early spring for early summer harvest, or in late/summer or early fall for a late fall harvest. Most varieties are ready to harvest in 55 to 75 days.

Botanical Name Brassica oleracea L. subsp. acephala
Common Name Collard greens, collards, tree cabbage
Plant Type Biennial vegetable; usually grown as an annual
Size 20 to 36 in. tall; 24- to 36-in. spread
Sun Exposure Full sun to part shade
Soil Type Moist, fertile, well-drained
Soil pH Slightly acidic (6.5 to 6.8)
Native Area Mediterranean and Asia Minor
Hardiness Zones 6 to 11 (USDA); grown as an annual in all zones
Toxicity Non-toxic
collard greens growing

The Spruce / Autumn Wood

top of collard greens

The Spruce / Autumn Wood

early stage of collard greens growth

The Spruce / K. Dave

How to Plant Collard Greens

You can start collard plants from seed or nursery transplants. Start seeds outdoors about two weeks before your last spring frost date or get a head start by sowing seeds indoors, four to six weeks earlier, and planting the seedlings right around your last frost date—these plants can readily handle chilly spring weather. For a fall harvest in cool climates, plant in mid-summer, about six to eight weeks before the first fall frost date. With protection, you can harvest collard greens well into winter.

Sow seed 1/4 to 1/2 in. deep. Collards are large, open plants. You can space them 18 to 24 inches apart or plant them more thickly, then thin and eat young plants until you reach the desired spacing.

In USDA hardiness zones 8 and higher, you will get your tastiest crop by planting in the fall and harvesting throughout the winter. Cool weather sweetens most cooking greens and collard greens are no exceptions.

Collard Green Care

Light

Collard greens prefer to grow in full sun but will tolerate some shade. A shady location may slow bolting in warmer climates.

Soil

Collards prefer rich soil with lots of organic material, with a pH level of 6.5 to 6.8.

Water

Keep the plants well-watered and harvest regularly to keep them sending out new leaves. These plants need 1 to 1 1/2 inch of water weekly. Mulch will keep the soil moist and the leaves clean.

Temperature and Humidity

Collard greens are a cool-season vegetable that will usually go to seed (bolt) when the weather grows warm in mid-summer. For this reason, they are often planted early or late rather than for mid-summer harvest. Collard greens can take a light frost, but you will lose your plants if the temperatures stay below freezing for long periods. To continue harvesting in cold areas, protect your collard greens with some type of hoop house or cold frame. Collards do equally well in humid and dry conditions, provided the soil is kept moist.

Fertilizer

Side dress with composted manure or a slow-release fertilizer every four to six weeks to keep the plants growing through repeated harvests.

Varieties

Collards are often grouped by two growing characteristics: those that are loose-leaf and those that form a loose head. Traditional varieties, such as 'Vates' and 'Georgia', form loose, open plants. Some of the newer hybrids, such as 'Morris Heading', grow quickly and curve in on themselves, forming a loose head and a more compact plant. Loose heading varieties are good choices if you want to harvest the whole plant at once. If you want a steady supply of leaves, opt for a loose-leaf variety.

  • 'Champion' is a 'Vates' hybrid, with cabbage-like leaves that store well. Good for smaller gardens, this variety matures in 60 days.
  • 'Flash' is a smallish plant but a very vigorous grower. The leaves are smooth and sweet; the plant matures in 55 days.
  • 'Georgia' is a large plant with tender, waxy leaves. Heat tolerant and slow to bolt, it matures in 75 days.
  • 'Green Glaze' has glossy, dark green leaves that are less often damaged by caterpillars. It matures in 75 days.
  • ' Vates' is a compact plant with very smooth leaves. It matures in 75 days.

Harvest

You can harvest leaves as needed or cut the entire plant. If you cut the entire plant while it is still young, the crown should resprout for at least one additional harvest. Harvest leaves while they are smooth and firm; young, tender leaves will be the least bitter. You can store them in damp paper towels for about three to four days, but the longer they are stored, the more bitter they become. It's better to harvest as needed.

Collard greens are very versatile. You can try the traditional method of boiling them, but you can also leave them with some substance and either lightly steam, sauté, or braise them.

There's good reasoning behind the phrase "mess o' greens." One pound of uncooked leaves yields about a 1/2 cup of cooked greens. Some favorite collard green recipes include:

  • Southern Style Collards
  • Raw Collard Greens with Ginger
  • Sautéed Collards and Kale

Propagating

Collards are biennial, so plants will need to be overwintered if you plan to save seed since they will not flower until the second year. After the plants flower, allow the seed pods to dry out until they are very hard and brittle, then collect the pods between paper towels and apply pressure to break the pods and collect the seeds.

Common Pests and Diseases

Collards are affected by the same diseases and pests as other members of the cabbage family, although their tough leaves offer some protection.

Be on the lookout for aphids, cabbage loopers, cabbage worms, cabbage root maggots, flea beetles, and even slugs. Whenever possible, use a non-toxic control method, such as citrus oil or insecticidal soap.

Common diseases include blackleg, black rot, clubroot, and cabbage yellows. Diseases tend to build up in the soil, so do not plant collards in the same spot every year. Rotate all your cruciferous vegetables and if you have a disease or pest problems, don't leave them standing through the winter.