Cosmic Crimson

Lettuce

Zone 5b Save Garden

Botanical illustration of Cosmic Crimson

🌱 45d to harvest Rosette

Velvety leaves unfurl in a spell of deep crimson and wine-red veining, with a cool, crisp snap that feels almost luminous. Cosmic…

Crop Dates

Milestone	Date
Start Indoors	Direct Sow
Last Frost	May 4th
Transplant / Sow Outdoors	May 4th
Harvest Begins	Jun 18th
Harvest Ends	Oct 5th

Crop Details

Trait	Value
Days to Maturity	45
Sun Requirements	Part Sun
Growth Habit	Rosette
Support Needed	None
Planting Depth	Surface
Germination Temp (°F)	70
Min Soil Temp (°F)	40
Min Night Temp (°F)	30
Harden Off (days)	5

Recommended Companions

Kyoto Tan Gawa Cucumber

Frequently Asked Questions

What’s the most common pest or disease problem for Lactuca sativa (Lollo Rossa-type) and how do I fix it?

Lactuca sativa commonly develops downy mildew in cool, humid conditions; look for pale yellow spots on the leaf tops and a gray-violet fuzz underneath. Remove and discard affected leaves, improve airflow between plants, and avoid watering the foliage (water at the soil line). If it keeps spreading, use a labeled fungicide for lettuce downy mildew according to the package directions and don’t replant into the same soil immediately.

How often should I water Lactuca sativa during the main growing phase to prevent problems?

During the main growth (about weeks 2–6), keep the top 1 inch of soil evenly moist with about 1 inch of water per week, adjusting for heat and container size. Water early in the day so leaves dry quickly, and stop letting the soil swing from very wet to very dry—irregular moisture can trigger bitterness and bolting. Mulch lightly (e.g., thin straw) to stabilize moisture without smothering the crown.

How can I tell when Lactuca sativa (Cosmic Crimson/Lollo Rossa type) is ready to harvest?

Harvest at around 45 days when heads or leaf clusters are fully formed for the variety and leaves are tender rather than tough. For cut-and-come-again, you can start taking outer leaves when they reach about 4–6 inches long and the center looks healthy. If you see a quick upward shoot forming (bolting), harvest immediately—once bolting starts, leaf flavor turns more bitter.

Velvety leaves unfurl in a spell of deep crimson and wine-red veining, with a cool, crisp snap that feels almost luminous. Cosmic Crimson forms an airy loose rosette of tender, finely textured foliage—sweet-green at the heart, richly colored toward the edges—for standout freshness in salads and vibrant garnishes. Grow it for 45 days to maturity and enjoy its bright, garden-to-table appeal in leafy mixes and quick tosses, where its color stays beautifully vivid.

Sowing Tips

Transplant Conditions

Wait until soil reaches 40°F and nights stay above 30°F before moving outdoors. Harden off for 5 days first.

Expert Note

For best bolt resistance, keep lettuce evenly moist and give it morning sun with afternoon shade as temperatures rise.