Plant nutrition for lettuce: recommendations by phenological stage

Growth Stages

Lettuce (Lactuca sativa) is a short-cycle crop widely produced in intensive systems. Adequate plant nutrition is key to achieving good-quality leaves, rapid development, and stress tolerance.

Here you will find general recommendations for each phenological stage to optimize lettuce crop productivity.

Germination and emergence

Duration: 2 to 5 days after sowing, depending on temperature and humidity.

Characteristics:

• Seed imbibition
• Tegument rupture
• Hypocotyl emergence and appearance of cotyledons

Optimal conditions:

• Temperatures between 18–22 °C
• Soil with good structure and constant moisture

Leaf Development

Duration: First to third week after sowing or transplanting.

Characteristics:

• Development of true leaves
• Progressive increase in leaf area

Agronomic relevance:

• Critical stage for Nitrogen (N) nutrition
• Requires adequate Phosphorus (P) supply to stimulate root system

Head Formation

Duration: 2 to 3 weeks

Characteristics:

• Central leaves begin to wrap around the growing point
• Initiation of “hearting” in romaine or escarole varieties.

Agronomic management:

• High demand for Potassium (K) and Calcium (Ca) for firmness, structure, and commercial quality
• Controlled irrigation to avoid water stress that affects head formation

Harvest Maturity

Characteristics:

• Head reaches desired commercial size depending on variety
• Crisp texture, uniform color, and well-formed leaves

Harvest indicators:

• Varies depending on type (butterhead, romaine, iceberg, etc.)
• Generally between 55 and 75 days after transplanting

Considerations:

• Avoid excess late Nitrogen, which promotes disease.
• Harvest early in the day to prevent loss of turgidity

Flowering and bolting

• Undesirable in commercial leaf production.
• Occurs when the plant responds to stress (high temperatures, long photoperiod).
• Affects quality, texture, and flavor (bitterness).

Prevention:

• Maintain proper temperature and irrigation management.
• Grow varieties adapted to the season and local climate.