When to plant cucumbers in Everett, WA

Warmth is everything

Cucumbers are a tropical crop. Seeds need soil of at least 60°F to sprout and do best much warmer, and long spells below about 50°F damage plants. In much of the Northwest, transplants or seeds go out only once nights are reliably warm. Black plastic mulch, a south-facing spot and row cover early in the season help.

Flowers and fruit set

Most cucumbers make separate male and female flowers, and bees carry pollen between them. Fruit from poorly pollinated flowers grows misshapen, narrow or curled at one end.

Some modern varieties set fruit with no pollination at all. These parthenocarpic varieties, such as Diva, produce seedless fruit and are a smart choice for greenhouses and for cool, cloudy summers when bees are scarce. Other hybrids are mostly female and come with a few marked seeds of a pollinator variety; plant those too.

Water and bitterness

Cucumbers are about 95 percent water, so they need steady moisture, about an inch a week, more in hot weather. Bitter cucumbers come from natural compounds called cucurbitacins, which increase when plants are stressed by heat, drought or uneven watering. The bitterness concentrates near the stem end and in the skin. Even watering prevents most of it, and burpless varieties are bred to be low in these compounds.

Soil and disease

Grow them in rich, well-drained soil with a pH of about 6.0 to 7.0. Trellising keeps fruit clean and straight and improves airflow, which slows powdery mildew in late summer. Resistant varieties like Marketmore 76 hold up longer. Slugs are the main threat to seedlings here.

Harvest and storage

Pick slicers at 6 to 8 inches and picklers at 2 to 4, checking every day or two. Leaving a mature, yellowing cucumber on the vine signals the plant to stop setting new ones. Cucumbers are chill-sensitive, so they keep best around 50 to 55°F; in the fridge, use them within a few days before they soften and pit.