Green Gem

Lettuce

Zone 10b Save Garden

🌱 55d to harvest Rosette

Cool, crisp hearts emerge in a vivid Green Gem—tender, sweet-leaning leaves with a clean, refreshing crunch and a beautifully upr…

Crop Dates

Milestone	Date
Start Indoors	Dec 4th
Last Frost	Jan 1st
Transplant / Sow Outdoors	Jan 1st
Harvest Begins	Feb 25th
Harvest Ends	Dec 31st

Crop Details

Trait	Value
Days to Maturity	55
Sun Requirements	Part Sun
Growth Habit	Rosette
Support Needed	None
Planting Depth	Surface
Germination Temp (°F)	40
Min Soil Temp (°F)	40
Min Night Temp (°F)	35
Harden Off (days)	6

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Frequently Asked Questions

What pest or disease most often affects Lactuca sativa (lettuce), and how do I control it?

For lettuce, aphids and downy mildew are common. Spray aphids off with a strong jet of water and, if needed, use an insecticidal soap, targeting the undersides of leaves; remove heavily infected leaves to slow down downy mildew. Keep soil off the lower leaves by avoiding overhead watering and spacing plants so leaves dry quickly after rain or irrigation.

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.

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.

Sowing Tips

Transplant Conditions

Wait until soil reaches 40°F and nights stay above 35°F before moving outdoors. Harden off for 6 days first.

Expert Note

For crisp, sweet heads, keep soil consistently moist and avoid heat stress—target cool weather and harvest before summer spikes.