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Collard Greens

Leafy Green
Cool season
Full sun

Also known as: Collards · Brassica oleracea var. viridis

Varieties

3 types of collard greens

When & where

Season
Cool season — extremely cold-hardy; frost sweetens flavor
USDA zones
Biennial in zones 3–11; overwinters in zones 7+
Sun
Full sun
Start indoors
6–8 weeks before last frost or midsummer for fall crop
Direct sow outdoors
3–4 weeks before last frost; again 12 weeks before first fall frost
Days to harvest
60–75 days

Germination

Germination time
5–10 days
Soil temperature
60–75°F (15–24°C)

Spacing & depth

Sow depth
1/4–1/2" (6–12 mm)
Seed spacing
2 in, thin to 18–24 in
Mature plant spacing
18–24 in (45–60 cm)
Row spacing
30–36 in (75–90 cm)

How to plant

Transplant or direct-sow into deeply worked fertile soil. Harvest outer leaves from the bottom up — the plant keeps making new ones from the top like a mini palm tree. A hard frost turns starches to sugars; fall-harvested collards are unbeatably sweet.

Grower's tip

The most heat-tolerant cabbage-family green — a rare Southern brassica that shrugs off summer. Plants can top 3 ft and produce for a full year in mild climates.

Soil preferences

Soil type

Rich, moisture-retentive loam.

pH range

6.0–7.0

Amendments

Compost + a light nitrogen source (blood meal, aged manure) — greens are all leaf, so they want nitrogen.

Watering

Frequency

Consistent — 1 in per week minimum, more in heat. Uneven water triggers bolt.

Method

Overhead is fine in the morning; drip is best in humid climates.

Over vs. under

Overwatered: soft rot at the crown, yellow lower leaves. Underwatered: bitter flavor, tough leaves, premature bolting.

Top-water or bottom-water?

Prefers top-watering — Top-water (overhead or rain) — grains are wind-pollinated and tolerate wet foliage. Water deeply and infrequently.

Temperature tolerance

Ideal daytime air temp

55–75°F (13–24°C) — most greens bolt above 80°F (27°C)

Ideal nighttime air temp

45–60°F (7–16°C)

Frost sensitivity

Light frost tolerated by most; kale, spinach, mâche, and collards are cold-hardy and often sweeter after frost.

Container growing

Container-suitable?

Yes — great in containers

Recommended pot size

6–8 in deep, any width; a window box works

Notes

Perfect for pots and hydroponics; cut-and-come-again mixes give weeks of harvest per sowing.

Succession planting

Every 2 weeks spring and fall. Skip the hottest weeks or use shade cloth.

Detailed harvesting

Cut outer leaves and let the crown keep producing (cut-and-come-again), or cut the whole rosette 1 in above the crown for a fresh flush.

Post-harvest storage & preservation

Rinse, spin dry, and store in a sealed bag with a paper towel in the crisper 5–7 days. Blanch and freeze for cooking greens.

Culinary, medicinal & other uses

Salads, sautés, smoothies, soups. Bitter or overgrown leaves are best cooked, not raw.

Medicinal or traditional uses are shared for interest only — this is not medical advice. Consult a qualified professional before using any plant medicinally.

Seed saving

Pollination

Lettuce is self-pollinating; spinach is wind-pollinated; brassica greens (kale, arugula, mustard) are insect-pollinated and cross freely.

Isolation needs

Lettuce 20 ft; spinach 1/2 mile; brassicas 1/4 mile or cage.

How to save

Let a robust plant bolt; harvest dry seed stalks; rub clean; store dry.

Your zone's planting calendar

Pick your USDA hardiness zone and we'll estimate the key dates for collard greens in your area. These are regional averages — always check your own last-frost forecast before sowing.

From your kitchen — grow collard greens from what you already have

Let one plant bolt (send up its flower stalk) and it will make hundreds to thousands of seeds. Bolted greens are bitter to eat but perfect for saving.

  1. 1Pick your best, slowest-to-bolt plant as the seed parent.
  2. 2Let the flower stalk rise, bloom, and dry brown on the plant.
  3. 3Cut the whole stalk into a paper bag before it shatters.
  4. 4Rub between your hands to release seed; sieve out chaff; store dry.

Storage: 3–5 years dry.

My Collard Greens notes

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