Black Summer
Brassica rapa var. chinensis
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Broad, flat, light green petioles are topped with dark green oval-shaped leaves. Best for full size, but also suitable for mini heads. Slightly smaller in size (10-12") and a complement to the white-stemmed Joi Choi. Very slow-bolting.
Harvest
45d
Days to harvest
Sun
Full sun to part shade
Zones
5–9
USDA hardiness
Height
3 feet
Planting Timeline
Showing dates for Black Summer in USDA Zone 7
All Zone 7 lettuce →Zone Map
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Black Summer · Zones 5–9
Growing Details
Zone-by-Zone Planting Calendar
| Zone | Indoor Start | Transplant | Direct Sow | Harvest |
|---|---|---|---|---|
| Zone 3 | — | — | May – June | June – October |
| Zone 4 | — | — | April – June | June – October |
| Zone 5 | — | — | April – May | May – November |
| Zone 6 | — | — | April – May | May – November |
| Zone 7 | — | — | March – May | May – November |
| Zone 8 | — | — | March – April | April – December |
| Zone 9 | — | — | February – March | March – December |
| Zone 10 | — | — | January – March | March – December |
| Zone 1 | — | — | June – July | July – September |
| Zone 2 | — | — | May – July | July – September |
| Zone 11 | — | — | January – February | February – December |
| Zone 12 | — | — | January – February | February – December |
| Zone 13 | — | — | January – February | February – December |
Succession Planting
Direct sow Black Summer every 14–18 days starting around March 1 in zone 7, and keep going through early May. Stop once daytime highs are consistently hitting 85°F — bok choy bolts fast under heat stress, and the leaves turn bitter and tough before the seed stalk is even fully visible. Pick back up with sowings in late August through September for a fall run; harvest should carry into November before hard frost finishes it. One 4-foot row per sowing is plenty for a family of four.
Complete Growing Guide
Broad, flat, light green petioles are topped with dark green oval-shaped leaves. Best for full size, but also suitable for mini heads. Slightly smaller in size (10-12") and a complement to the white-stemmed Joi Choi. Very slow-bolting. According to Johnny's Selected Seeds, Black Summer is 45 days to maturity, annual, hybrid (f1). Notable features: Cold Tolerant, Hydroponic Performer, Heat Tolerant.
Light: Full sun (6 or more hours of direct sunlight a day), Partial Shade (Direct sunlight only part of the day, 2-6 hours). Soil: Clay, Loam (Silt), Sand. Soil pH: Acid (<6.0), Neutral (6.0-8.0). Drainage: Good Drainage, Moist. Height: 0 ft. 10 in. - 2 ft. 0 in.. Spread: 1 ft. 0 in. - 2 ft. 0 in.. Spacing: 12 inches-3 feet. Growth rate: Medium. Maintenance: Medium. Propagation: Seed, Stem Cutting. Regions: Coastal, Mountains, Piedmont.
Harvesting
Black Summer reaches harvest at 45 days from sowing per Johnny's Selected Seeds. Expect 10-12" at peak. As an annual, harvest continues until frost ends the season.
The fruits dry and split when ripe.
Color: Brown/Copper, Green. Type: Siliqua. Length: > 3 inches.
Garden value: Edible
Harvest time: Fall, Summer
Bloom time: Spring, Summer
Edibility: The foliage is edible raw or cooked but when cooked can emit an unpleasant odor.
Storage & Preservation
Black Summer lettuce reaches harvest maturity in 45 days and stores best at 32–35°F with 95% humidity in perforated plastic bags within a standard refrigerator crisper drawer. Under these conditions, expect 7–10 days of acceptable freshness before wilting becomes pronounced. For longer preservation, freezing works adequately if you blanch leaves briefly (2–3 minutes) before plunging into ice water, then pat dry and pack in freezer bags; this method maintains texture better than raw freezing for cooked applications like soups. Fermentation is also viable—layer shredded leaves with salt (2–3% by weight) in a clean jar, weight down, and allow 3–5 days at room temperature for tangy results. This darker Asian type holds its color and crunch slightly longer than lighter lettuces when kept properly sealed and cold, making it worth the small effort of prompt refrigeration immediately after cutting.
History & Origin
Black Summer is an F1 hybrid developed through controlled cross-pollination. Listed in the Johnny's Selected Seeds catalog.
Brassica is a genus of plants in the cabbage and mustard family (Brassicaceae). The members of the genus are informally known as cruciferous vegetables, cabbages, mustard plants, or simply brassicas. Crops from this genus are sometimes called cole crops—derived from the Latin caulis, denoting the stem or stalk of a plant.
Advantages
- +Slow-bolting variety ideal for extended harvests and summer growing
- +Attractive dark green leaves with light green stems offer visual appeal
- +Versatile sizing works well for both full-size and mini head production
- +Easy difficulty level makes it accessible for beginner gardeners
- +Compact 10-12 inch size fits well in small spaces and containers
Considerations
- -Smaller mature size may yield less volume compared to larger varieties
- -Light-colored petioles can show dirt and cosmetic damage more visibly
- -Moderate disease susceptibility typical of Asian greens requires preventative care
- -Requires consistent moisture and rich soil for optimal leaf quality
Companion Plants
Radishes and Tagetes patula marigolds are worth putting closest to Black Summer — radishes germinate in 5–7 days and pull flea beetles onto themselves before those beetles start punching holes in your bok choy, while marigolds push back on aphid pressure through sulfur-compound emissions from their roots and foliage. Chives and garlic work on the same principle. Keep broccoli at least 24 inches off: in our zone 7 Georgia gardens, large brassicas share a nutrient draw and bring overlapping pest populations — armyworms, cabbage loopers — right into the same bed. Skip fennel entirely; it produces anethole and other root exudates that suppress germination and stunt nearby vegetables, bok choy included.
Plant Together
Chives
Repels aphids and other soft-bodied insects that commonly attack lettuce
Carrots
Deep taproots don't compete with shallow lettuce roots, helps break up soil
Radishes
Quick-growing, helps break up compacted soil and can be intercropped
Marigolds
Natural pest deterrent, repels nematodes and various garden pests
Garlic
Strong scent deters aphids, slugs, and other lettuce pests
Spinach
Similar growing requirements, can be succession planted together
Dill
Attracts beneficial insects like ladybugs that prey on lettuce pests
Nasturtiums
Acts as trap crop for aphids and cucumber beetles, draws pests away from lettuce
Keep Apart
Broccoli
Large leaves create too much shade and compete for nutrients
Sunflowers
Allelopathic compounds inhibit lettuce germination and growth
Fennel
Inhibits growth of most garden plants through allelopathy
Walnut Trees
Produce juglone, a natural herbicide toxic to lettuce and many other plants
Nutrition Facts
Per 100g serving. % Daily Value based on 2,000 calorie diet. Source: USDA FoodData Central (FDC #2346388)
Pests & Disease Resistance
Common Pests
Aphids, slugs, snails, flea beetles, armyworms
Diseases
Downy mildew, lettuce mosaic virus, septoria leaf spot, bottom rot
Troubleshooting Black Summer
What you'll see, why it happens, and what to do about it.
Seedlings collapsing at the soil line within the first 7–10 days after transplanting or germination, sometimes with a fuzzy whitish mold on the soil surface nearby
Likely Causes
- Damping off — typically Pythium or Rhizoctonia solani — a soilborne fungal complex that thrives in wet, poorly drained conditions
- Overwatering or compacted soil that stays saturated after planting
What to Do
- 1.Pull the dead seedlings and check the stem base: if it's pinched or water-soaked at the soil line, damping off is almost certainly the culprit
- 2.Don't replant into the same spot immediately — let the bed dry out, then amend with compost to improve drainage before resowing
- 3.NC State Extension's IPM guidance recommends rotating away from beds where you've grown lettuce-family crops three or more consecutive seasons; take that seriously here
Yellow angular patches on upper leaf surface with a grayish-purple fuzzy coating on the underside, showing up during cool, wet stretches in spring or fall
Likely Causes
- Downy mildew (Bremia lactucae) — spreads fast when nights stay below 65°F and humidity is high
- Overhead irrigation that keeps foliage wet overnight
What to Do
- 1.Remove and bag affected outer leaves; trash them, don't compost
- 2.Switch to drip irrigation or water only in the early morning so leaves dry before evening
- 3.If the planting is badly infected, pull it and direct-sow a new round at least 18 inches from the affected spot — Black Summer is a hybrid but carries no advertised resistance to local Bremia strains
Ragged holes chewed through leaves overnight, with no caterpillars visible during the day; small slime trails sometimes visible at dawn
Likely Causes
- Slugs or snails — especially common in mulched beds after rain in spring and fall
- Flea beetles (Phyllotreta spp.) — leave smaller, cleaner shot-holes and feed during warm daytime hours
What to Do
- 1.For slugs: scatter iron phosphate bait (Sluggo) around plant bases at dusk; reapply after heavy rain
- 2.For flea beetles: cover transplants with row cover (Reemay or equivalent) right after setting out — damage is worst on plants under 3 inches tall
- 3.Pull back thick mulch from the immediate crown to cut slug habitat without losing moisture retention further out
Frequently Asked Questions
How long does Black Summer lettuce take to mature?▼
Is Black Summer lettuce good for beginners?▼
Can you grow Black Summer lettuce in containers?▼
What does Black Summer lettuce taste like?▼
Does Black Summer need full sun to grow?▼
When should I plant Black Summer lettuce?▼
Growing Guides from Wind River Greens
Where to Buy Seeds
Sources & References
External authority sources used in compiling this guide.
- BreederJohnny's Selected Seeds
- USDAUSDA FoodData Central
See the Methodology page for how this data is sourced, what's AI-assisted, and known limitations.