Collard greens, a heat-tolerant staple in southern US cuisine, is a delicious and healthy addition to gardens everywhere. Although technically a biennial, it’s mostly grown as an annual crop for its high yield of large, dark-colored, edible leaves. Plants will grow up to 2 feet tall, and, unlike their cabbage relatives, do not sprout a head. Collards are in the same group as kale and have many similar health benefits of plants in the brassica family. When young, it can be eaten raw in salads; older greens taste better cooked.

Green Glaze collards are a variety of greens that have had a prominent place in Southern cooking for over a hundred year thanks to their beautiful, shiny green foliage, ability to withstand both hot and cold weather, and strong, spicy taste. Although able to grow in most climate zones, this variety prefers the more mild weather found in the southeastern regions of the US, particularly along the coast. Green Glaze collards also tend to be more resistant to pests that plague other collards, such as cabbage loopers and cabbage worms, thanks to their waxy skin, which is also responsible for their shiny appearance.

  • Botanical Name: Brassica oleracea Acephala Group
  • Plant Type: Vegetable
  • Variety: Green Glaze
  • Growth Cycle: Annual Biennial
  • Season(s): Spring Summer Fall Winter
  • Climate Zone(s): 3a 3b 4a 4b 5a 5b 6a 6b 7a 7b 8a 8b 9a 9b
  • Light: Full Sun
  • Soil Type(s): Loamy
  • Yield: 2 lbs per plant
  • Garden Dimensions: 1 plant per 2' x 2' square
  • Germination: 10–15 days
  • Maturity: 75–100 days
  • Harvest: 75–100 days



Seed Depth: 1/2″
Space Between Plants: 12″
Space Between Rows: 18–24″
Germination Soil Temperature: 60–70°F
Days for Germination: 10–15
Sow Indoors: 6 weeks before average last frost date.
Sow Outdoors: 2–4 weeks before average last frost date. For a fall crop, 10–12 weeks before average first frost date.


While this variety of collards can withstand temperatures as low as 0°F and as high as 90°F for short periods of time, they prefer more mild weather and will do best in most regions when planted for a late spring and/or early fall harvest. Fall crops harvested after the first light frost will have the best flavor and sweetest taste. If you’re growing in USDA Zones 8 and higher, collards can be grown throughout the winter.


Natural: Full sun.

Artificial: Grows well under fluorescent, LED, or metal halide HID lamps. Collards like a lot of sunlight but not too much heat, so keep lights on your plants for at least 10 hours a day. Make sure to hand lamps 6″ or more from the tops of your seedlings.

Growing Media

Soil: Prefers well-drained loamy soil with a high amount of organic matter. A pH of between 6.5 and 6.8 will keep plants healthy and nourished.

Soilless: Plants will grow well in soilless mixes that drain well, such as those that contain coco coir, perlite, and/or vermiculite.

Hydroponics: Thrives in a variety of hydroponic systems, and will do particularly well in ebb and flow type systems.


Water: Requires moderate levels of water. Aim for about 1–1.5 inches of water per week or just enough water to keep your soil moist but not soggy.

Nutrients: Requires moderate to high levels of nutrients. Apply a high nitrogen fertilizer, such as fish emulsion, if growth appears to be slow.

Foliar: Will benefit from foliar feedings of nitrogen-rich compost tea or fish emulsion every couple weeks.

Mulching: Use an organic mulch such as hay, bark chips, or well-rotted compost to keep weeds under control, moderate soil temperature, and conserve moisture.



  • Aphids
  • Cabbage loopers
  • Cabbage worms
  • Cutworms
  • Diamond back moth
  • Flea beetles


  • Alternaria leafspot
  • Black leg
  • Black rot
  • Club root
  • Downy mildew
  • Root rot
  • Wirestem

Deficiency(s): A nitrogen deficiency can cause slow growth or yellowing of leaves.

Rotation and Companion Plants

Rotation: A 4-year rotation away from all plants in the brassica family is recommended.

Companions: Grows well with beets, bush beans, celery, chamomile, cucumber, dill, garlic, marigolds, mint, nasturtium, onions, potatoes, rosemary, sage, and thyme. Avoid grapes, pole beans, tomato, strawberry, and Mexican marigolds.

Harvest and Storage

Harvest: Pick leaves as needed, starting with lower outer leaves. Leaves will be best if harvested when under 10″ in length. You can harvest the entire plant when young for salad greens or when mature for use in cooking. If you wait until after the first light frosts to harvest a fall crop, leaves will be sweeter.

Storage: Leaves can be refrigerated in a plastic bag for about a week. Cool leaves quickly once they’re picked to extend storage life.

Other Info

History: As collard greens were once considered to be a food for the poor, many varieties never gained popularity outside of their localities in commercial markets and were lost over time. Perhaps because of its tolerance to pests and temperature changes, the Green Glaze variety of collards has managed to endure. It’s become one of the oldest, domestically cultivated varieties in the US since its creation by Dr. David Landreth in 1820.


Preserve and Prepare

Preserve: Leaves or roots can be blanched and frozen or pickled.

Prepare: Most commonly eaten cooked: try steaming, boiling, or sautéing for different nuances of flavor and texture. Collards are a staple in southern cooking. A simple but delicious preparation involves lightly sautéing in olive oil and adding salt and pepper. Baby greens are tasty in salads, but older ones will be too tough and fibrous without cooking. Some cultures also frequently consume the plant’s roots.


Nutritional: Provides vitamin(s) C, K, dietary fiber, and antioxidants.

Medicinal: As with other cruciferous vegetables, some studies have indicated that consuming collard greens can reduce the risk of certain types of cancers, including prostate and pancreatic. The fiber in collard greens has also been linked to reducing blood sugar, while its content of vitamin K is thought to potentially improve bone density and health.

Warnings: Because of its vitamin K content, collards should be eaten only in moderation by anyone taking blood thinning medication.


Although collards are traditionally prepared with ham or chicken broth, adding beans can make for a hearty and delicious dish without the meat. Try this Cannellini Beans and Collard Greens recipe once your Green Glaze is ready for harvest!


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