How to grow collards
Family Brassicaceae. Hardy to USDA hardiness zone 3a+ (U.S. Department of Agriculture). Full sun to part shade. Ready in 60-85 days.
Sun
Full sun to part shade
Spacing
18-24 in
Days to harvest
60-85 days
Hardiness
Zone 3a+
What growers actually recorded
Loading zone 7b results…
When to plant collards
- Start indoors: ~5 weeks before last frost.
- Transplant out: ~-2 weeks after last frost.
- Direct sow: ~-2 weeks after last frost.
Companion plants for collards
Plant with: Onion, Dill, Thyme, Beet.
Avoid near: Tomato, Strawberry.
Common pests & problems
Cabbage worm, aphid, harlequin bug, flea beetle.
Feeding & fertilizer
N-P-K ratio: High N (10-5-5): heavy feeders
Organic options: Aged manure or compost worked in deep · Blood meal or feather meal side-dress at 3 wks · Fish emulsion every 2 wks
When to feed: Feed heavily every 2-3 weeks. Brassicas want steady nitrogen for tight heads.
Watch for: Pale/yellow leaves = needs N. Loose heads = feed harder next round.
N = nitrogen (leaves), P = phosphorus (roots and flowers), K = potassium (fruit and disease resistance). How to read a fertilizer label →
Grower's tip
The most forgiving green in the garden. Harvest bottom leaves upward and it produces for months. Leaves picked after a frost are noticeably sweeter.
When to plant collards in your zone
Free month-by-month sowing and transplanting lists, built from frost dates for your USDA (United States Department of Agriculture) hardiness zone.
Soil & water for collards
Soil & pH
6.5-7.5: near neutral (raises club-root resistance)
Fertile loam with strong drainage. Firm soil beats fluffy for heading brassicas.
Compost 2 in + 1 cup of alfalfa or feather meal per 10 sq ft. Lime if pH is under 6.5. It also blocks club-root.
Watering
1-1.5 in / week, consistent
Ground-level drip. Uneven water during heading = split heads or bolting.
Lift an edge of the row and check soil at 3 inches. If it clings in a damp ball, hold off. If it crumbles, water until the top 6 inches are evenly moist.
Knowing when to harvest
- Outer leaves reach 8-10 in and are dark green and firm.
- Harvest lower leaves continuously, leaving the crown to keep producing.
- Flavor sweetens after light frost, similar to kale.
Storing & keeping
Refrigerate unwashed in a perforated bag at 32-40°F for 1-2 weeks. Blanch 3 minutes and freeze; holds texture well for long-term storage.
What to expect
Per plant: 1-2 lb over a season with repeat picking
Per sq ft: 0.5-1 lb per sq ft
Troubleshooting collards
Holes chewed through leaves
Likely cause: Cabbage worms or harlequin bugs
What to do: Row cover early, hand-pick harlequin bugs, use Bt for caterpillars.
Leaves turn tough and bitter
Likely cause: Hot, dry weather
What to do: Mulch to keep roots cool and water consistently; harvest younger leaves in summer.
Varieties worth growing
Georgia Southern
Heat-tolerant heirloom bred for Southern gardens, slow to bolt.
Vates
Compact, cold-hardy, widely available and reliable.
Champion
Slow-bolting selection good for extended harvest windows.
Growing collards in containers
5-gallon pot, one plant per pot; tolerates containers well given consistent water and monthly feeding.
Nutrition
Sulforaphane, glucosinolates, vitamin K, calcium. Brassicas are the vegetable powerhouse.
Common questions
How is collard harvest different from cabbage?
Collards don't form a head; individual leaves are picked continuously from the bottom up over months, like kale, rather than harvested once.
Can collards overwinter?
In zone 7 and warmer, yes, with mulch; they tolerate hard frosts down into the low 20s°F and often improve in flavor after cold exposure.
Where these numbers come from
- USDA Plant Hardiness Zone Map (2023 revision). Zone assignment and the 30-year normals behind every cold-hardiness figure.
- NOAA NCEI 1991-2020 Climate Normals. Frost dates, growing-season length, and the probability bands on both.
- Cornell, UMN, and UC Davis Cooperative Extension crop guides. Spacing, days to maturity, soil pH targets, and per-plant yield ranges.
- USDA FSIS / FDA Produce Safety guidance. Wash, cure, and cold-storage handling numbers.
Ranges are regional guidance, not a promise for your yard. Your own logged results always override the published range.