Image source: Depositphotos.com

Overview

• Name: Collard Greens
• Botanical Name: Brassica oleracea var. viridis
• Plant Family: Brassicaceae
• Native to: Eastern Mediterranean and Asia Minor (derived from wild cabbage, which originated in these regions)

Description

Collard greens (also known as tree cabbage or non-heading cabbage) are a leafy, non-heading, wild form of cabbage that is a biennial plant grown as annuals for their large, smooth, oval leaves. Plants have an erect, upright form and typically reach 60–90 cm (2–3 ft) in height, forming a loose rosette rather than a firm head. Stems are thick, branching at times, and the leaves have prominent veins with broad petioles (leaf stems). The leaves can be dark green to bluish-green and develop a waxy coating that helps them retain moisture.

If allowed to overwinter or bolt, collards produce small, yellow, four-petaled flowers typical of the Brassica family, followed by slender seed pods containing round seeds. Though technically biennial, most gardeners harvest leaves throughout the growing season and do not allow the plant to flower unless saving seeds.

Collard leaves can be eaten raw when they are small and tender, while the larger, tougher, more mature leaves can be cooked, stewed, braised, stir-fried, or made into chips much like kale.

Collard greens are nutrient-rich and closely related to cabbage, broccoli, and kale (Image source: Depositphotos.com)

Interesting Facts

1. Collards are among the oldest cultivated members of the cabbage family, originating from wild cabbages in the eastern Mediterranean and Asia Minor. Archaeological evidence shows they were eaten in prehistoric times. The name “collard” comes from the Old English colewort, meaning “cabbage plant.” Ancient Greeks and Romans cultivated collards, and around 400 B.C., they were introduced to Britain and France—either by Roman settlers or migrating Celts. In North America, the first recorded mention of collards dates to 1669, though they may have arrived even earlier.
2. Botanically, collard greens are closely related to other Brassicas, including cabbage, broccoli, and kale.
3. Collard greens, along with kale and mustard greens, are part of the traditional “Southern greens” in the United States, especially in African American cuisine. They have deep historical significance, tracing back to African cooking traditions. Slow-simmered collards with smoked meats remain a cultural and culinary staple in many Southern communities.
4. These nutrient-rich leaves are high in vitamin K, vitamin A, vitamin C, and dietary fiber. Some research indicates that collards provide compounds with potential anticancer properties, similar to other cruciferous vegetables. Their ability to thrive in diverse climates also makes them a valuable source of fresh greens.
5. Collard greens tolerate light frosts, and a mild freeze can enhance their flavor, reducing bitterness and increasing sweetness. This cold tolerance allows them to be grown across a broad range of regions—often providing fresh, nutritious greens well into late autumn or early winter, depending on local climates.
6. In addition to the leaves, many gardeners use young, tender collard stems in soups and sautés. When harvested at an early growth stage, collard greens offer a softer texture and milder flavor. Mature leaves are heartier, well-suited for stewing and braising, as they maintain structure through extended cooking times.

Basic Growing Information

Collard greens are a cool‐season crop that thrives in temperatures ranging from 13-18 °C (55-65 °F). Once established, plants tolerate light frosts and even withstand lows to -6.7 °C (20 °F), frequently developing a sweeter flavor after exposure to frost. Seeds will germinate in soils as cool as 7 °C (45 °F) and plants will continue productive growth when monthly averages reach 21 °C (70 °F). However, sustained temperatures above 27 °C (80 °F) can reduce both yields, toughen leaves, cause leaves to develop a stronger flavor and trigger premature bolting (flowering and going to seed).

Plants prefer well-drained, fertile soil enriched with organic matter, with regular watering to maintain constant moisture levels.

In regions with hot summers, sowing seeds in early spring or late summer is best, so plants mature during the cooler weather.

In cooler climates, sow seeds directly into the soil after the danger of frost has passed, or start seeds indoors 4–6 weeks before the last frost. The optimum soil temperatures for germination are generally 12–24 °C (55–75 °F). Seedlings started indoors (or in a cold frame) are ready to be transplanted when they have 5–6 true leaves, which indicates that they have reached a sufficient level of growth to adapt effectively to outdoor conditions.

• Sun Requirements: Full sun to partial sun
• Water Requirements: Medium (consistent watering)
• Soil Types and Properties: Fertile, well-draining loamy soil with added compost
• Soil pH: 6.0–6.5
• Pot Size for Container Growing: 30–40 cm (12–16 in) diameter or larger for mature plants

Planting

• Best Time to Plant:
  • Climates with freezing winters: Early spring for a late-spring harvest or mid- to late summer for a autumn/winter crop
  • Climates with milder winters: Late winter or early spring; can also be grown through winter if temperatures remain mild

Note: Check gardening calendars for the best planting times in your location

• Spacing: 40–45 cm (15–18 in) between plants; 75–90 cm (30–36 in) between rows
• Seed Sowing Method: Sow seeds directly into the ground or start in seed trays for transplanting
• Seed Sowing Depth: 0.5-1 cm (1/4-1/2 in) deep
• Time to Harvest: 6–8 weeks (for baby leaves) and 8–11 weeks (for mature leaves)
• Mature Height/Spread: 60–90 cm (2–3 ft) tall and wide
• Grown From: Seeds

Care and Maintenance

• Watering Tips: Aim to keep the soil evenly moist. Water at the base of the plant rather than overhead, to reducing leaf wetting and minimize the risk of fungal diseases. Mulch the soil surface helps retain moisture and regulate soil temperature, promoting steady growth.
• Fertilization: Collards require moderate amounts of fertilizer. Before planting, enrich the soil with well-rotted compost or a balanced organic fertilizer. As plants grow, especially if leaves appear pale or growth stalls, apply a side dressing of fertilizer to encourage leafy development. Avoid excessive nitrogen in very warm weather, which can lead to overly rapid, weak growth.
• Pruning: Although not required, removing lower, yellowing leaves helps direct energy to new leaf formation and improves airflow around the plant base. In some cases, gardeners employ a “cut-and-come-again” approach, consistently harvesting outer leaves to keep the plant producing. This approach effectively “prunes” older foliage while encouraging vigorous new growth.
• Support: Mature collard plants sometimes reach heights where strong winds or heavy leaf canopies may cause leaning. If plants become top-heavy, inserting a stake into the ground and loosely tying the central stem offers stability. Ensure that stakes don’t damage the shallow root system, as minimal disturbance helps the plant maintain healthy growth.

Growing Difficulty

• Easy to Grow

Growing Tips

• To optimize flavor and texture, time your planting so collards mature in cooler weather—this may mean planting in late summer or early autumn. Mild frosts can actually improve leaf sweetness. Where winters are mild, overwintering plants provide a steady supply of leaves, often lasting until spring sets in.
• When weeding around the plants, it is preferable to hand-pull any weeds, as collards have shallow roots and it is important to avoid damaging them.
• Practice crop rotation, avoiding planting collard greens in the same spot where other Brassicas (like cabbage, broccoli or kale) grew the previous year. This reduces the risk of soil-borne diseases, pests (like cabbage root maggots), and localized nutrient depletion, helping maintain soil health for better yields.
• When harvesting continuously, remove only the oldest outer leaves at any one time. This lets younger leaves at the top continue growing. Regular harvesting not only yields fresh greens but also promotes healthy, ongoing leaf production without allowing the plant to become oversized or less tender.

Companion Plants

• Good companion plants include: Onions and garlic (alliums that repel common brassica pests), beets and spinach (shallow‐rooted crops that interplant well), herbs such as dill (which attract beneficial predators like lady beetles and lacewings), and marigolds (Tagetes spp.), which—when grown as a preceding cover crop—can suppress soil nematodes
• Avoid planting near: Strawberries, which have been shown to be antagonistic when grown beside brassicas, and other Brassica crops in immediate succession—maintain at least a 3–4 year rotation (or up to 7 years where clubroot is a concern) to break cycles of clubroot, black rot, Alternaria, and related soil-borne diseases

Common Pests and Diseases

• Pests:
  • Cabbage Worms & Loopers – Handpick or spray with Bacillus thuringiensis (Bt); row covers are effective early in the season
  • Aphids – Wash off with water or use insecticidal soap; encourage beneficial insects like ladybugs
  • Flea Beetles – Place sticky traps; mulch and row covers help protect seedlings

• Diseases:
  • Clubroot – Maintain proper soil pH; practice crop rotation; remove and destroy infected plants
  • Black Rot – Improve airflow; avoid overhead watering; remove infected leaves promptly
  • Downy Mildew – Provide adequate spacing; water early in the day; remove heavily infected foliage

Harvesting

Harvest Time:

• Baby leaves: Ready 10–15 days after sowing for microgreen-style harvests.
• First tender leaves: Approximately 6-8 weeks (42-56 days) after direct seeding, when leaves reach about 20-25 cm (8-10 in) long.
• Mature leaves: Typically 60-80 days (8-11 weeks) after sowing, depending on cultivar.
• Seasonal note: Light autumn frosts often improve sweetness, and you can continue harvesting into cold weather until the plants are damaged by hard freezes.

Harvesting Tips:

1. Cut-and-come-again: Use clean scissors or a sharp knife to snip only the outer, mature leaves at their base—always leaving the central growing point and at least two-thirds of the foliage intact.
2. Avoid overharvest: Never remove more than one-third of the plant at once; this keeps collards vigorous and productive.
3. Sequential picking: Harvest leaves from the bottom upward, allowing younger leaves to mature for later picks.
4. Whole-plant harvests (optional): Entire plants may be cut when half-grown or full-grown. For very young or full-size plants, you may cut the whole stem at soil level; collards often regrow for a second harvest.
5. Timing by season:
   • For the spring crop, flavor is best if you harvest the plants before the weather becomes hot and dry to avoid tough, bitter leaves.
   • For the autumn crop, the cooler the weather, the better the flavor, until freezing temperatures stop the plant’s growth.

Storage:

• Fresh use: Collards are best enjoyed fresh through the cool season rather than preserved. Since you can harvest the leaves of collard greens well into the cold season, it is traditional to eat them until they are gone rather than trying to store them. Freezing is an option if you have a particularly abundant crop.
• Refrigeration: Store unwashed, loosely bundled leaves in a perforated plastic bag in the crisper drawer for up to 2 weeks.
• Freezing (optional): Blanch leaves briefly, cool in ice water, drain well, and freeze in airtight containers for long-term storage.

Propagation

• Produce New Plants From: Seeds

Culinary Uses

Collard greens are a culinary mainstay in many parts of the world, most famously in Southern U.S. cuisine. Slow simmering is a classic preparation, often combined with smoked meats (like ham hocks or bacon) and seasoned with onions, garlic, or chilies. This cooking style mellows their hearty flavor and renders the fibrous leaves tender. In other regions, lighter cooking methods are popular. For instance, collard greens may be sautéed with olive oil and garlic or briefly blanched before adding to stews, providing an earthy balance to robust flavors.

Beyond these methods, collards’ sturdy leaves make them suitable as wraps for fillings—an alternative to tortillas or cabbage leaves. Lightly steaming or blanching them softens the leaves, making them pliable enough to roll around grains, proteins, or vegetables. When fresh and young, collard greens are tender enough to be thinly sliced into salads or slaws. Combining them with bright dressings or citrus highlights their slightly sweet, earthy character.

Collards can also be chopped and added to soups, lending body and nutrients to broths. Because they hold up well under heat, they won’t disintegrate quickly, giving soups a heartiness. Pairing them with beans, tomatoes, or root vegetables creates a satisfying, nourishing meal. The mild flavor accommodates various seasonings, from smoked paprika to curry blends, making collard greens a versatile addition to global cuisines. Whether braised in a rustic Southern dish or folded into a modern fusion recipe, collards bring a nutritious, fibrous depth to the table.

In conclusion, collard greens are a resilient, easy-to-grow crop that can adapt to a wide range of climates. With proper soil preparation, consistent watering, and timely harvest, you can enjoy a season-long supply of nutritious leaves that enrich your kitchen with everything from classic comfort foods to inventive new recipes.

References

• Smith, P. (2025, January 30). Collards | Home & Garden Information Center. Home & Garden Information Center. https://hgic.clemson.edu/factsheet/collards/
• Collard Greens | NC State Extension Publications. https://content.ces.ncsu.edu/collard-greens
• Growing collards and kale in home gardens. University of Minnesota. UMN Extension. https://extension.umn.edu/vegetables/growing-collards-and-kale
• Andersen, C. R. (2009). Collards (Home Gardening Series No. FSA6067) [Fact sheet]. University of Arkansas System Division of Agriculture, Cooperative Extension Service. https://www.uaex.uada.edu/publications/PDF/FSA-6067.pdf
• Collard greens | Diseases and Pests, Description, Uses, Propagation. PlantVillage. https://plantvillage.psu.edu/topics/collard-greens/infos