How Often Should You Fertilize Lettuce in a Container?

Potted Lettuce

• Lettuce features wide, leafy foliage growth with relatively shallow root systems. Grow lettuce in wide, shallow pots and containers with drainage holes to allow leaf spreading and drainage. Use 3-gallon pots and larger containers that measure at least 4 inches deep for lettuce.

Potting Soil

• Lettuce grows best in moist, fertile soil and requires better moisture retention in pots and indoors. The soil for growing lettuce should have a high organic content -- potting soils, peat moss, organic compost and vermiculite support potted vegetables well. Organic matter gives lettuce seeds and plants immediate long-lasting nutrition and moisture retention.

Fertilizer

• Start lettuce seeds with 5-10-10 fertilizer for quick germination and root growth. Plant the seeds 1/4 to 1/2 inch deep, and water the lettuce with 2 inches of water every week. Give lettuce water-soluble 20-20-20 or 15-30-15 fertilizer at midseason to encourage fuller growth. Lettuce is not a hungry plant and doesn't require frequent feedings.

Harvest

• Harvest all lettuce when it reaches its desired size and when leaves are green and juicy. Lettuce grows bitter and woody as it ages. Cut the entire plant off at soil level and continue to care for the roots for a possible second harvest.