Romaine Lettuce – Malenita RZ

Description

SCIENTIFIC NAME:

Lactuca sativa

CULTURE:

Lettuce is a hardy, cool-weather crop and can be planted with your earliest worked soil. It grows best at 16–18°C and germinates best below 21°C, so careful variety selection is key for success in hotter weather. Sow every 2–3 weeks for a continuous supply of either full heads or salad mix.

THERMAL DORMANCY:

Lettuce seed can enter thermal dormancy when exposed to high temperatures. Optimum germination results at soil temperatures of 16-20°C. The priming process in pelleted lettuce seeds broadens the temperature range in which the seeds will germinate, overcoming some of their thermal dormancy.

TRANSPLANTING for HEAD LETTUCE:

3–4 weeks before field planting, sow in 128-cell trays barely covered with vermiculite or fine soil. If necessary, utilize shade and frequent misting to keep trays cooled below 25°C during germination. Young plants properly hardened at least 3–5 days before planting can survive temperatures as low as -6°C. Transplant iceberg, romaine, and butterhead lettuce 25-30 cm apart in rows 40-45 cm apart, other types 20-25 cm  apart in rows 30-45 cm, and mini heads as close as 15 cm in a grid.

HARVEST:

Head Lettuce: Cut at base, keeping wrapper leaves for handling loss. Consider cutting alternating plants to extend harvest window, allowing remaining plants to continue to grow. Pack heads in layers facing cut ends away. Wash off sap and cool immediately to prevent staining and dehydration. 

STORAGE:

Keep cold at 1–4°C with high humidity but free of standing water. Head Lettuce: Keep 14–20 days, less for delicate types like butterhead and oakleaf, and longer for lettuce grown slowly in cooler temperatures. For one-cut types, extend season in cold weather by holding cut heads in cooler up to two weeks to process into salad mix.