Last Updated on September 14, 2026
Lettuce
Lettuce is a cool-season leafy vegetable in the Asteraceae family. It is grown in four main forms: looseleaf, butterhead/Bibb, romaine/cos, and crisphead/iceberg. UC ANR notes that looseleaf lettuce is the type most commonly grown in home gardens because it matures quickly and can be harvested repeatedly, while head types generally require a longer period of cool weather.
Lettuce is especially well suited to the cooler months of Zone 9. Arizona Extension recommends daytime temperatures around 60–70°F and nighttime temperatures around 40–60°F for both head and leaf lettuce. High temperatures encourage bolting, bitterness, loose heads, and tipburn, making fall through spring the primary production period in most Zone 9 locations.
See our full How to Grow Lettuce in Zone 9 article.
Planting Windows for Zone 9
| Stage | Spring | Fall / Winter |
|---|---|---|
| Start Indoors | Dec 15 – Jan 31 | Jul 15 – Aug 31 |
| Direct Sow | Jan 1 – Mar 1 | Aug 15 – Nov 1 |
| Transplant | Jan 15 – Mar 15 | Sep 1 – Nov 15 |
| Harvest | Feb 15 – May 1 | Oct 1 – Feb 28 |
Recommended Lettuce Varieties
Buttercrunch — Butterhead lettuce widely recommended by UC ANR. Produces tender, crisp leaves and performs well in home gardens.
Salad Bowl — Fast-growing looseleaf lettuce recommended by UC ANR. Well suited to repeated “cut-and-come-again” harvesting.
Red Sails — Red looseleaf variety recommended by UC ANR; productive and useful for cool-season gardens.
Oakleaf — Looseleaf type recommended by UC ANR, producing tender lobed leaves and relatively quick harvests.
Little Gem — Compact romaine type recommended by UC ANR; useful where garden space is limited.
Parris Island — Classic green romaine recommended by UC ANR and commonly used for both full heads and baby-leaf production.
Rouge d’Hiver — Red-tinged romaine recommended by UC ANR and useful during cool conditions.
Breen — Compact romaine type recommended by UC ANR.
Nevada — Summercrisp lettuce identified by UF/IFAS as heat tolerant and slow to bolt, making it particularly useful during Zone 9 shoulder seasons.
New Red Fire — Red leaf lettuce listed by UF/IFAS as heat tolerant and slow to bolt.
Tropicana — Bright-green leaf lettuce listed by UF/IFAS with good heat tolerance and slow bolting.
Coastal Star — Dark-green romaine listed by UF/IFAS as heat tolerant and productive.
Fertilizer Schedule
Incorporate compost or organic matter and apply fertilizer according to soil-test recommendations.
Use a modest amount of balanced fertilizer if soil fertility is low.
Apply a light nitrogen side-dressing.
Apply another light feeding if growth is pale or slow, especially in sandy soil.
For cut-and-come-again leaf lettuce, light supplemental feeding can support continued regrowth.
Planting Details
Growing Requirements
Top 5 Common Lettuce Pests
Aphids
Colonies develop on leaves and in tightly folded heads. Leaves may curl or become distorted, and sticky honeydew can promote sooty mold. Aphids can also contaminate harvested leaves and transmit viruses. UC IPM lists aphids among major lettuce pests.
Vegetable Leafminers
Larvae tunnel between the upper and lower leaf surfaces, producing winding white or translucent mines. Heavy infestations reduce photosynthetic area and make leaves unmarketable. UF/IFAS identifies leafminers as important lettuce pests in Florida.
Cutworms
Seedlings may be cut off near the soil line, often overnight. Larger larvae may also chew foliage. UC IPM lists cutworms among significant lettuce pests.
Loopers / Armyworms
Caterpillars chew irregular holes through foliage and can contaminate heads with frass. Heavy feeding can severely reduce usable leaf area. UC IPM lists both loopers and armyworms as lettuce pests.
Slugs and Snails
Irregular holes develop in leaves, often accompanied by shiny slime trails. Young seedlings can be heavily damaged. UC ANR specifically lists slugs and snails among common lettuce problems.
Top 5 Common Lettuce Diseases
Downy Mildew
Light-green to yellow angular spots develop on upper leaf surfaces. White fluffy growth appears underneath affected areas, and lesions eventually turn brown and dry. UC IPM notes that damp, cool conditions and leaf moisture strongly favor infection.
Lettuce Drop / White Mold
Lower leaves wilt and collapse, followed by soft decay near the crown. White cottony fungal growth may develop around the base of infected plants. UC IPM lists white mold/Sclerotinia lettuce drop as a major lettuce disease.
Damping-Off
Seeds may rot before emergence, while seedlings develop dark, constricted stems and collapse near the soil line. UC IPM lists damping-off among lettuce diseases.
Botrytis Rot / Gray Mold
Soft brown lesions develop on leaves, followed by gray fuzzy fungal growth. Injured or aging foliage is especially vulnerable. UC IPM lists Botrytis rot among important lettuce diseases.
Lettuce Mosaic / Other Virus Diseases
Leaves may develop mottling, distortion, stunting, uneven growth, or reduced head formation. UC IPM lists lettuce virus diseases among important problems.
Zone 9 Weather Patterns
Harvest
Varies by lettuce type, variety, and harvest method.
Spring: February 15 – May 1
Fall / Winter: October 1 – February 28
Leaf lettuce can be harvested whenever individual leaves reach usable size. Butterhead, romaine, and crisphead types should be harvested when heads are appropriately sized, firm, and still tender. Harvest before plants begin elongating or sending up a flower stalk because bolting produces increasingly bitter leaves.
For cut-and-come-again production, remove a few outer leaves from each plant while leaving the center intact. UC ANR recommends taking 2–3 leaves per plant while allowing the remaining plant to continue growing. Whole plants can also be cut at the base; leaving approximately 1 inch of stem may allow regrowth. Head lettuce should be harvested once heads become firm and before bolting begins.
Crop Relationships
Asteraceae — Daisy / Sunflower Family
Asteraceae / Leafy Greens
Sweet Alyssum
Calendula
Cilantro
Dill
Marigolds
Endive
Escarole
Chicory
Radicchio
Other lettuce crops
Helpful Links
Data Sources & Methodology:
The crop data presented in this guide represents standardized Zone 9 values derived from and averaged across guidance from UF/IFAS Extension, Texas A&M AgriLife Extension, University of Arizona Cooperative Extension, and UC Agriculture & Natural Resources. USDA establishes the Zone 9 plant-hardiness framework. Recommendations may vary by local climate, cultivar, soil conditions, microclimate, and individual growing conditions.
