Planting Timeline
Showing dates for Great Lakes in USDA Zone 7
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Great Lakes · Zones 3–9
Growing Details
Zone-by-Zone Planting Calendar
| Zone | Indoor Start | Transplant | Direct Sow | Harvest |
|---|---|---|---|---|
| Zone 3 | March – April | May – June | May – July | July – September |
| Zone 4 | March – April | May – June | April – July | July – October |
| Zone 5 | February – March | April – May | April – July | June – October |
| Zone 6 | February – March | March – May | March – August | June – October |
| Zone 7 | January – March | March – April | March – August | May – November |
| Zone 8 | January – February | February – April | February – September | May – December |
| Zone 9 | December – February | January – March | January – September | April – December |
Complete Growing Guide
Growing Great Lakes lettuce successfully starts with choosing the right location and timing. This variety thrives in cool weather, so plan your plantings for early spring (4-6 weeks before your last frost) or late summer for fall harvest. Choose a spot with morning sun and afternoon shade in warmer climates, or full sun in cooler regions.
Prepare your soil by working in 2-3 inches of compost or well-aged manure to a depth of 8-10 inches. Great Lakes demands rich, loose soil with excellent drainage – soggy conditions will cause root rot and poor head formation. Test your soil pH and aim for 6.0-6.8; anything too acidic will stunt growth and increase disease susceptibility.
For spring crops, start seeds indoors 4-6 weeks before transplanting. Sow seeds ¼ inch deep in seed starting mix at 60-65°F. Once seedlings have 2-3 true leaves, transplant outdoors spacing plants 12-14 inches apart – closer spacing produces smaller, looser heads. For direct sowing, plant seeds ½ inch deep and thin progressively, eating the thinnings as baby greens.
Fertilize with a balanced 10-10-10 fertilizer at planting, then side-dress with nitrogen-rich fertilizer (like fish emulsion) every 3 weeks during active growth. Stop nitrogen feeding 3 weeks before expected harvest to encourage proper head formation and prevent loose, leafy growth.
Consistent moisture is critical – maintain 1-1.5 inches weekly through drip irrigation or soaker hoses. Overhead watering can promote disease and cause tip burn on developing heads. Mulch around plants with 2 inches of straw to retain moisture and suppress weeds.
Avoid these common mistakes: planting too early in hot weather (causes bolting), overcrowding (leads to disease), and irregular watering (causes bitter leaves and tip burn). In zones 7-9, grow Great Lakes as a winter crop for best results.
Harvesting
Harvest Great Lakes lettuce when heads feel firm and dense, typically 85-90 days from seed. The outer leaves should wrap tightly around the center, and heads should measure 6-8 inches across. Test readiness by gently pressing the center – it should feel solid with minimal give, not soft or spongy.
Harvest in early morning when leaves are crisp and full of moisture. Cut the entire head at soil level using a sharp knife, leaving the root system intact. Don't wait too long after heads mature – they'll become bitter and may bolt, especially in warming weather.
You can also harvest outer leaves individually while the center continues developing, but this method works best early in the season. If heads start elongating or you notice the center pushing upward, harvest immediately regardless of size – the plant is beginning to bolt and leaves will turn bitter quickly.
Storage & Preservation
Store freshly harvested Great Lakes lettuce in the refrigerator crisper drawer wrapped in damp paper towels, then placed in a perforated plastic bag. Properly stored heads stay fresh and crisp for 1-2 weeks at 32-36°F with high humidity.
For longer storage, remove any damaged outer leaves, rinse the head briefly in cold water, and shake dry before wrapping. Never store near ethylene-producing fruits like apples or tomatoes, which cause rapid deterioration.
While lettuce doesn't preserve well through traditional methods, you can extend its usefulness by chopping and freezing it for cooked applications like soups and stir-fries. Dehydrating creates crispy lettuce chips when seasoned and dried at 135°F. The thick, crisp leaves also work well in fermented vegetables when combined with cabbage for sauerkraut-style preparations.
History & Origin
Great Lakes lettuce was developed in the 1940s by the Ferry-Morse Seed Company as a heat-tolerant alternative to traditional iceberg lettuce varieties. Plant breeders specifically created this variety to address the challenges home gardeners faced when trying to grow crisp head lettuce in variable climate conditions.
The variety gained widespread popularity in the 1950s and 1960s as suburban gardening expanded across America. Unlike commercial iceberg varieties that required specific cool coastal conditions, Great Lakes could produce decent heads in a wider range of climates and growing conditions.
This heirloom variety represents an important bridge between commercial lettuce breeding and home garden practicality. While newer varieties have since been developed, Great Lakes remains valued for its reliability and the authentic crisphead lettuce experience it provides. Its development marked a significant advancement in making quality head lettuce accessible to home gardeners nationwide, rather than limiting successful cultivation to professional growers in ideal climates.
Advantages
- +Superior heat tolerance compared to traditional iceberg varieties, extending growing season
- +Forms dense, well-blanched heads even in less-than-ideal conditions
- +Excellent resistance to tip burn, a common problem with crisphead lettuces
- +Long shelf life after harvest - stays crisp for 1-2 weeks refrigerated
- +Reliable head formation without requiring precise timing or perfect weather
- +Thick, substantial leaves hold up well to dressings and don't wilt quickly
- +Good bolt resistance when grown in appropriate seasons
Considerations
- -Long 85-90 day maturity makes it challenging in short growing seasons
- -Still susceptible to downy mildew in humid conditions despite moderate resistance
- -Requires consistent moisture - irregular watering causes bitter leaves and poor heads
- -Takes up considerable garden space with 12-14 inch spacing requirements
- -Can become bitter if exposed to temperature stress or allowed to mature too long
Companion Plants
Plant Together
Chives
Repels aphids and improves lettuce flavor while providing natural pest deterrent
Carrots
Deep roots don't compete with shallow lettuce roots, helps aerate soil
Radishes
Quick-growing companions that help break up soil and deter root maggots
Marigolds
Repel nematodes and aphids while attracting beneficial insects
Garlic
Natural fungicide properties help prevent lettuce diseases like downy mildew
Spinach
Similar growing requirements and helps maximize space in cool-season gardens
Dill
Attracts beneficial insects and may improve lettuce growth when young
Nasturtiums
Act as trap crops for aphids and cucumber beetles, protecting lettuce
Keep Apart
Broccoli
Heavy feeder that competes for nutrients and can shade lettuce excessively
Sunflowers
Allelopathic compounds inhibit lettuce germination and growth
Parsley
Can stunt lettuce growth when planted too closely due to root competition
Pests & Disease Resistance
Resistance
Good resistance to tip burn, moderate resistance to downy mildew
Common Pests
Aphids, slugs, cutworms, flea beetles
Diseases
Downy mildew, lettuce drop, bottom rot, tip burn