SproutSmart
SproutSmart Intelligent Garden Sowing

Green Gem

Lettuce

Planting Schedule

Add Green Gem to your garden to build a schedule and get reminders.
Botanical illustration of Green Gem
55d to harvest

Cool, crisp hearts emerge in a vivid Green Gem—tender, sweet-leaning leaves with a clean, refreshing crunch and a beautifully upright romaine form. At maturity in about 55 days, the foliage forms tight, elongated heads with a smooth, slightly glossy surface and a gently ribbed texture that stays crisp in the garden. Ideal for fresh salads and vibrant sandwiches, Green Gem also shines in quick tosses and bright, leaf-forward platters where its sturdy structure holds up with grace.

Crop Dates

MilestoneDate
Start IndoorsFeb 23rd
Last FrostMar 23rd
Transplant / Sow OutdoorsMar 23rd
Harvest BeginsMay 17th
Harvest EndsNov 12th

Crop Details

TraitValue
Days to Maturity55
Sun RequirementsPart SunPartial sun
Growth HabitRosette
Support NeededNone
Planting DepthSurface
Germination Temp (°F)40
Min Soil Temp (°F)40
Min Night Temp (°F)35
Harden Off (days)6

Frequently Asked Questions


How often should I water Lactuca sativa during the main growing phase?
During active leaf growth, keep the top 1–2 in (2.5–5 cm) of soil evenly moist but not waterlogged to prevent tip burn and bitterness. In most home gardens this works out to about 1 in (2.5 cm) of water per week, adjusted so the soil never dries out fully between waterings. Water early in the day and focus on the soil line to avoid wet foliage.
How can I tell when Green Gem (Lactuca sativa) is ready to harvest?
Harvest when heads are firm and have reached the variety’s typical size at about 55 days, and leaves feel crisp rather than limp. For loose-leaf lettuce, you can also do a cut-and-come-again harvest, taking outer leaves once they’re large enough to eat. If you see the center starting to bolt (rapid stem growth), harvest immediately to avoid tough, bitter leaves.
Botanical illustration of Green Gem

Cool, crisp hearts emerge in a vivid Green Gem—tender, sweet-leaning leaves with a clean, refreshing crunch and a beautifully upright romaine form. At maturity in about 55 days, the foliage forms tight, elongated heads with a smooth, slightly glossy surface and a gently ribbed texture that stays crisp in the garden. Ideal for fresh salads and vibrant sandwiches, Green Gem also shines in quick tosses and bright, leaf-forward platters where its sturdy structure holds up with grace.