Lettuce in Zone 7A — Pacific Northwest

Lettuce thrives in our mild Pacific Northwest summers, where cool nights and temperatures that rarely climb above 90°F create ideal conditions for crisp, flavorful leaves. Unlike gardeners in hotter climates who struggle with bitter, bolted lettuce by midsummer, you can grow exceptional salad greens nearly year-round here. The gentle heat means your lettuce develops slowly and stays tender, while our dry summer air helps prevent many of the fungal diseases that plague lettuce in humid regions.

Our wet springs and cool soil can delay early plantings, and slugs love our moist conditions, but proper timing makes these challenges manageable. With a 183-day growing season and our long, mild fall, you have plenty of opportunities to succession plant and enjoy fresh lettuce from early May through late October.

Starting lettuce seeds indoors makes sense if you want an earlier harvest or better control over germination during our unpredictable spring weather. Sow seeds in early to late March, about four weeks before you plan to transplant outdoors. Our slow spring start means indoor sowing gives you a real head start over direct seeding.

Use standard seed trays with quality potting mix, keeping seeds at 60-70°F for best germination. Bottom watering works well for lettuce seedlings since it prevents the tiny seeds from washing around. Place trays near a sunny window or under grow lights once seeds sprout.

Your seedlings will be ready to transplant in early to mid-April, giving you fresh lettuce by early May instead of waiting for direct-sown crops to mature later in the season.

Transplant lettuce seedlings outdoors from early April through mid-May, once soil temperatures reach about 45°F. Our cool spring nights won't harm these semi-hardy plants, but they need gradual adjustment to outdoor conditions. Harden off seedlings over a week by placing them outside for increasing periods each day.

Space transplants 6-12 inches apart depending on variety - leaf lettuce needs less room than head types. Plant them slightly deeper than they were growing in their containers to encourage strong root development. Our overcast spring days are perfect for transplanting since seedlings won't face immediate heat stress.

Lettuce starts are inexpensive and widely available at local nurseries, making this an easy option if you don't want to start from seed. The cool, moist conditions of our typical April weather help transplants establish quickly.

Direct sowing works exceptionally well for lettuce in our region since the seeds germinate easily in cool soil. Sow from late March through late August, with the soil temperature as low as 35°F for germination. Our cool springs actually favor lettuce over many other crops that need warmer soil.

Prepare beds with compost or well-aged manure, creating a fine seedbed for the small seeds. Sow seeds ¼ inch deep and thin seedlings to 6-12 inches apart once they're established. The cool, moist conditions of spring give you excellent germination rates without the damping-off problems common in hot, humid climates.

Succession sow every 2-3 weeks through late August to ensure continuous harvests. Our mild summers mean you can keep planting much later than gardeners in hotter zones, taking advantage of those cool September and October days for perfect fall lettuce.

Lettuce needs consistent moisture since its shallow roots dry out quickly, but our dry summer climate makes this manageable without the fungal issues that plague lettuce in humid regions. During our dry summer months, plan to water 2-3 times per week, providing about 1 inch of water total. The cool nights and mild daytime temperatures mean lettuce uses water efficiently here.

Use the finger test - stick your finger 2 inches into the soil near the plants. If it feels dry at that depth, it's time to water. Water at the base of plants rather than overhead to keep leaves dry, especially important during our occasional humid spells or morning dew periods.

Watch for signs of stress: wilting during the day indicates underwatering, while yellowing leaves and soft stems suggest overwatering. Our well-draining Pacific Northwest soils rarely stay soggy, but poor drainage in clay soils can cause problems during wet spring periods.

Mulch around plants with straw or shredded leaves to retain moisture and keep soil cool during our warmest summer days. This is especially helpful in late July and August when even our mild heat can stress lettuce if the soil dries out completely.

Expect your first lettuce harvest in early May if you started with transplants, or late May to early June for direct-sown crops. With our long, mild growing season extending through late October, you'll have months of fresh lettuce before the first frost arrives. The cool nights throughout summer help maintain that crisp texture and sweet flavor.

For leaf lettuce, harvest outer leaves when they reach 4-6 inches long, leaving the center to continue growing. Head lettuce is ready when the heads feel firm and full - don't wait too long or they may start to bolt. Cut the entire head just above soil level with a sharp knife in the early morning when leaves are crisp and full of moisture.

Keep harvesting regularly to encourage continued production and prevent bolting. Our mild summer temperatures mean lettuce rarely bolts from heat stress like it does in hotter climates, but long days in midsummer can still trigger flowering. Remove any plants that send up a tall center stalk since the leaves will turn bitter.

As our first frost approaches in mid-October, harvest remaining heads completely. The outer leaves may survive light frosts, but the quality deteriorates quickly once temperatures drop consistently below freezing.

Bolting shows up as a tall flower stalk shooting up from the center of the plant, causing leaves to become bitter and tough. In our mild Pacific Northwest climate, bolting is more often triggered by long summer days than heat stress, though drought can also cause it. Plant at appropriate times for each season, provide consistent moisture, and choose bolt-resistant varieties like 'Nevada' or 'Jericho' for summer plantings.

Aphids appear as clusters of tiny green, black, or white insects on leaf undersides and stems, leaving sticky honeydew residue and causing leaves to curl. These sap-suckers multiply quickly during warm spells, even in our mild summers. Blast them off with water spray, encourage beneficial insects like ladybugs, or use insecticidal soap for heavy infestations. Avoid high-nitrogen fertilizers which make plants more attractive to aphids.

Slugs create irregular holes in leaves and leave silvery slime trails - a major problem in our moist Pacific Northwest climate. They feed at night and hide under mulch or debris during the day. Set beer traps (shallow dishes sunk into soil), use iron phosphate bait around plants, and water in the morning so soil surfaces dry by evening. Remove hiding spots like boards and excess mulch near lettuce beds.

Tip burn appears as brown, dried edges on inner lettuce leaves, similar to blossom end rot in tomatoes. This calcium uptake problem results from inconsistent watering, which can happen during our transition from wet spring to dry summer. Maintain consistent soil moisture, ensure adequate soil calcium, and avoid fertilizers high in ammonium nitrogen. Provide shade during our warmest days in late July and August.

Our dry summer air helps prevent many fungal diseases that affect lettuce in humid climates, while our mild temperatures reduce heat stress. However, the transition from wet springs to dry summers requires attention to watering schedules, and slug pressure remains high throughout the growing season due to morning dew and irrigation moisture.

Plant lettuce with carrots and radishes, which make excellent companions in our Pacific Northwest gardens. Carrots and lettuce have different root depths and don't compete for nutrients, while radishes grow quickly and help break up soil around slower lettuce roots. The radishes also mature before lettuce needs full space, maximizing your bed efficiency during our long growing season.

Chives and strawberries work well near lettuce beds since chives help repel aphids with their strong scent, and strawberries provide some ground coverage without competing for the same soil nutrients. Avoid planting lettuce near celery or parsley, as these crops have similar nutrient requirements and growth habits, leading to competition for resources. In our mild climate where plants grow steadily rather than rapidly, this competition becomes more noticeable over the long growing season.