Planting Timeline
Showing dates for Black Seeded Simpson in USDA Zone 7
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Black Seeded Simpson · Zones 2–11
Growing Details
Zone-by-Zone Planting Calendar
| Zone | Indoor Start | Transplant | Direct Sow | Harvest |
|---|---|---|---|---|
| Zone 3 | — | — | April – August | June – October |
| Zone 4 | — | — | April – August | May – October |
| Zone 5 | — | — | April – August | May – October |
| Zone 6 | — | — | March – September | May – November |
| Zone 7 | — | — | March – September | April – November |
| Zone 8 | — | — | February – October | April – December |
| Zone 9 | — | — | January – November | March – December |
| Zone 10 | — | — | January – December | March – December |
Complete Growing Guide
Before planting Black Seeded Simpson, work 2-3 inches of compost into your soil to create the loose, fertile foundation this lettuce craves. The soil should drain well but retain moisture — if water pools after rain, add coarse sand or perlite to improve drainage.
Start your first crop by direct sowing seeds 2-3 weeks before your last frost date. Scatter seeds thinly in rows 12 inches apart, covering with just 1/4 inch of fine soil. The key to success with this variety is succession planting every 10-14 days through late spring, then resuming in late summer for fall harvests. Skip midsummer plantings in zones 6-9, as even heat-tolerant Black Seeded Simpson struggles in 85°F+ weather.
For indoor starts, sow seeds 4-5 weeks before transplanting. Use a cool location (60-65°F) and transplant while plants are still small — lettuce hates root disturbance. Harden off transplants for 3-4 days before setting them out.
Once established, side-dress with balanced organic fertilizer (10-10-10) every 3 weeks, focusing on nitrogen to promote leaf growth. Water consistently but avoid overhead watering, which promotes fungal diseases. Drip irrigation or soaker hoses work best.
The biggest mistake gardeners make is planting too thickly. Thin seedlings to 6-8 inches apart when they're 2 inches tall — crowded plants bolt faster and develop bitter flavors. Another common error is waiting too long between harvests. Cut leaves regularly to prevent the plant from putting energy into seed production.
For maximum yields, harvest outer leaves when they reach 4-5 inches, leaving the center growing point intact. This cut-and-come-again method can give you harvests for 6-8 weeks from a single planting. In hot climates, provide afternoon shade using row covers or taller companion plants like tomatoes.
Harvesting
Begin harvesting Black Seeded Simpson when outer leaves reach 4-5 inches long, typically 40-45 days from sowing. The leaves should feel tender but substantial — avoid the papery texture of overmature lettuce. For cut-and-come-again harvesting, use clean scissors or a sharp knife to cut outer leaves 1 inch above the soil line, leaving the central growing point undisturbed.
Harvest in early morning when leaves are crisp and full of moisture. Evening-cut lettuce tends to be more bitter and wilts faster. You can also harvest entire heads by cutting at soil level when plants reach 6-8 inches across.
Watch for signs that harvesting window is closing: elongating center stem, bitter taste, or leaves developing a tough, chewy texture. In hot weather, harvest becomes urgent as plants can bolt within days of showing these signs.
Storage & Preservation
Immediately after harvest, rinse Black Seeded Simpson leaves in cold water and spin dry thoroughly. Store in perforated plastic bags in your refrigerator's crisper drawer at 32-35°F with high humidity. Properly stored leaves stay fresh for 7-10 days.
Unlike storage vegetables, lettuce doesn't preserve well long-term. Your best options are freezing cleaned leaves in smoothie portions (texture will be lost but nutrition remains) or dehydrating young, tender leaves at 95°F for lettuce powder seasoning. Fermentation isn't recommended as lettuce lacks the structure needed for successful lacto-fermentation.
For continuous supply, focus on succession planting rather than preservation methods. Extend fresh harvests by growing under row covers as weather cools.
History & Origin
Black Seeded Simpson emerged in the 1850s as one of America's first widely distributed lettuce varieties, developed during the rapid expansion of market gardening around growing cities. The variety takes its name from the dark seeds that distinguish it from its white-seeded cousin, Simpson Elite.
This lettuce became a staple of 19th-century American gardens because it thrived in the variable conditions of frontier settlements. Unlike European heading lettuces that required consistent cool weather, Black Seeded Simpson could handle temperature swings and still produce tender leaves.
Seed companies like Burpee and Ferry promoted it heavily in their catalogs from the 1860s onward, making it one of the most widely grown lettuces in America by 1900. Its reliability during the Victory Garden campaigns of both World Wars cemented its place as a true American heirloom. Today, it remains essentially unchanged from those original 1850s selections, a testament to the quality of early plant breeding work.
Advantages
- +Exceptional heat tolerance compared to other loose-leaf varieties, extending harvest season
- +Cut-and-come-again harvesting provides 6-8 weeks of continuous production from single plantings
- +Adapts well to partial shade conditions where other lettuces fail
- +Germination remains reliable even in fluctuating spring soil temperatures
- +Mild, never-bitter flavor appeals to children and picky eaters
- +Matures quickly at just 40 days, perfect for impatient gardeners
- +Strong resistance to tipburn even in windy, dry conditions
Considerations
- -Bolts rapidly once temperatures exceed 80°F consistently for 3+ days
- -Susceptible to downy mildew in humid, crowded conditions
- -Leaves become tough and lose flavor quickly once plant begins to bolt
- -Requires consistent moisture — drought stress immediately affects leaf quality
- -Attracts aphids more readily than thick-leaved lettuce varieties
Companion Plants
Plant Together
Chives
Repels aphids and improves lettuce flavor while taking minimal space
Carrots
Deep roots don't compete with shallow lettuce roots, and carrots loosen soil
Radishes
Quick-growing radishes break up soil and can be harvested before lettuce needs full space
Marigolds
Repel aphids, whiteflies, and other pests that commonly attack lettuce
Spinach
Similar growing conditions and harvest times, efficient use of garden space
Garlic
Deters slugs, aphids, and other soft-bodied pests that damage lettuce leaves
Nasturtiums
Act as trap crop for aphids and cucumber beetles, protecting lettuce
Dill
Attracts beneficial insects like ladybugs that prey on lettuce pests
Parsley
Attracts beneficial insects and has similar water and nutrient requirements
Keep Apart
Sunflowers
Create too much shade and compete heavily for nutrients and water
Broccoli
Both are heavy nitrogen feeders that compete for the same nutrients
Walnut Trees
Release juglone which is toxic to lettuce and inhibits growth
Pests & Disease Resistance
Resistance
Good tolerance to heat stress and some resistance to tipburn
Common Pests
Aphids, flea beetles, slugs, cutworms
Diseases
Downy mildew, lettuce drop, tipburn, bolting in hot weather