Imperial 615

Lettuce

Zone 8b Save Garden

🌱 70d to harvest Rosette

Crisp as morning frost, Imperial 615 forms tightly packed heads with a cool, clean crunch and a gently sweet, fresh flavor. The l…

Crop Dates

Milestone	Date
Start Indoors	Feb 23rd
Last Frost	Mar 23rd
Transplant / Sow Outdoors	Mar 23rd
Harvest Begins	Jun 1st
Harvest Ends	Nov 12th

Crop Details

Trait	Value
Days to Maturity	70
Sun Requirements	Part Sun
Growth Habit	Rosette
Support Needed	None
Planting Depth	Surface
Germination Temp (°F)	45
Min Soil Temp (°F)	40
Min Night Temp (°F)	32
Harden Off (days)	5

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Frequently Asked Questions

What pest or disease most often affects Lactuca sativa (imperial/ice-type lettuce) and how can I control it?

Watch for downy mildew and aphids—lettuce (Lactuca sativa) is especially prone to downy mildew when nights are cool and humidity stays high. Improve airflow with wider spacing and water in the morning so leaves dry quickly, then remove badly infected plants to slow spread; for aphids, spray a strong jet of water off the underside of leaves and repeat every 2–3 days for a week. If downy mildew appears repeatedly, switch to a drier location or raised beds and avoid working in the crop when foliage is wet to reduce transmission.

How often should I water Lactuca sativa during the main growing phase (about weeks 2–6)?

Keep the soil evenly moist but not soggy from transplanting/thinning until heads are forming; aim for light, frequent watering rather than long dry spells. In typical home gardens, that often means watering 1–3 times per week depending on heat, with enough water to wet the top 4–6 in (10–15 cm) so roots stay consistently hydrated. Avoid overhead watering late in the day because wet foliage increases downy mildew risk.

How do I tell when my Lactuca sativa (70-day lettuce) is ready to harvest?

Harvest when the leaves form a firm, full head/compact rosette and the outer leaves are crisp and well-sized—this usually lines up around the 70-day mark from sowing/transplanting as your garden conditions allow. If the center starts to look elongated or leaves turn noticeably bitter, the plant is shifting toward bolting and should be harvested immediately. Cut in the morning for best crispness, leaving a short stump if you want to see limited regrowth from side leaves.

Crisp as morning frost, Imperial 615 forms tightly packed heads with a cool, clean crunch and a gently sweet, fresh flavor. The leaves are richly colored and satisfyingly crisp, holding their structure for dependable performance in the garden. Grow Imperial 615 for crisphead salads and elegant, refreshing platters where sturdy texture is the star.

Sowing Tips

Transplant Conditions

Wait until soil reaches 40°F and nights stay above 32°F before moving outdoors. Harden off for 5 days first.

Expert Note

For crisp, durable heads, keep soil consistently moist and aim for cool weather—heat and irregular watering are what reduce crispness even when tip burn is resistant.