Pest management: Lettuce cultural tips, pests, and diseases
Lettuce is usually grown as a cool-season crop in Santa Clara County. If grown in the summer, it's recommended to plant where it will get shade from other crops or trees and to select temperature tolerant, slow bolting, varieties. It's a shallow-rooted plant which requires frequent watering when there's no rain.
When to plant
- Transplant: Feb–Apr, Sept–Oct (maybe Aug and Nov)
- Direct seed: Mar-Apr (maybe Feb), Sept–Oct (maybe Aug and Nov)
- 'Baby' lettuce leaves can be harvested quite early, 30-45 days after planting.
- Leaf lettuce can be harvested as a loose head or over a period of time by breaking off the outside leaves and allowing the interior leaves to continue to develop.
- Harvest heading types when they are firm, but not hard. Before harvesting the entire head, outside leaves can be harvested regularly to prolong the harvest.
- Lettuce can also be broadcast and harvested as 'cut and come again' where the leaves are harvested above the growing tip and the plants are allowed to regrow.
- If seeding, plant more seeds than necessary so as to make up for any losses.
- Lettuce is best planted in succession or using different varieties that mature at different times.
- If lettuce begins to bolt (send up a flower stalk), the leaves often become unpalatably bitter, especially the ribs. When the sap in the cut leaves is milky instead of clear, it is an indication that the leaves may taste bitter.
Recommended Varieties for Santa Clara County*
|Blushed Butter Cos, OP||Tender, a semi-romaine type with a buttery texture, green leaves blushed with red. 5–7" tall. Plant 8–10" apart.|
|Buttercrunch, OP||Loose butterheads with sweet, crisp, thick, delicious leaves. 5–7" tall. Plant 8–10" apart.|
|Cardinale, OP||Thick, crisp and succulent dark red leaves on extremely heat resistant crispheads. Beautiful and tasty. 6–8" tall. Plant 10–12" apart.|
|Cimarron, OP||Red romaine heads, tall, crisp, and delicious, slow to bolt. Heirloom French variety. 5–7" tall. Plant 8–10" apart.|
|Flame, OP||Distinctly red looseleaf lettuce, slow bolting. Taste test winner in our red lettuce trial. 12–14" tall. Plant 8–10" apart.|
|Gourmet Baby Mixed, OP||Delicious blend of gourmet lettuces. Plant closely (2–4") for cut and come again harvesting or space apart 8–10" for heads.|
|Little Gem, OP||Miniature green romaine with sweet, blanched heart, a gourmet treat. 4–6" tall. Plant 6–8" apart.|
|Queen of Crunch, OP||Crunchy, juicy green leaves can be harvested individually or as the entire head. Heat tolerant and sturdy, this crisphead lettuce is beautiful in the garden. 6–8" tall. Plant 10–12" apart.|
|Rhapsody, OP||Large emerald green butterhead, delicious and slow to bolt. 6–8" tall. Plant 8–10" apart.|
|Tom Thumb, OP||Miniature green butterheads are just 3–4" across, perfect for individual salads. Heirloom from the 1850's. 4–5" tall. Plant 6" apart.|
|Valentine Mesclun, OP||Gorgeous mix of red lettuces for dramatic and delicious salads. Plant closely (2–4") for cut and come again harvesting or space apart 8–10" for heads.|
|Yugoslavian Red, OP||Tender red butterheads are beautiful and flavorful. 6–8" tall. Plant 8–10" apart.|
Other recommended varieties: Black-Seeded Simpson, Brune d'Hiver, Canasta, Capitaine, Esmeralda, Jericho, Loma, Marvel of Four Seasons, Merlot, Nancy, Nevada, Oakleaf, Prizehead, Red Ridinghood, Sangria, Sierra
* Many other varieties may also do well here in Santa Clara County. This list is based on UC Master Gardener trials, taste tests, and feedback from local growers.