During germination, a cuke’s shoot and first tiny root break through its seed coating. It only happens in sufficiently warm soil. To know when that is, stick with these planting guidelines:
Seeds in 80°F to 90°F (26.6°C to 32.2°C) soil take from 3 to 10 days to germinate.
Seeds in 65°F to 80°F (18.3°C to 26.6°C) soil take more 10 days to germinate.
Seeds planted in soil below 50°F (10°C) won’t germinate.
Plant your seeds no deeper than 1.5 inches and keep the soil moist — not saturated — while they germinate.
Expert gardener’s tip: Using a soil thermometer, measure the morning and late-afternoon temperatures for several days. When the average of the daily readings is consistently above 65°F (26.6° C), it’s safe to plant.
The Seedling Stage
Cuke seedlings emerge with primitive leaves called a cotyledon. Next are the true leaves they need to photosynthesize food. As soon as they put out vines, it’s wise to tie them loosely to a wooden trellis or other vertical support. They’ll be easier to water and harvest and less prone to diseases than if they sprawl on the ground.
Flowers and Early Fruit Development
Most cucumber varieties produce both male and female flowers, with the first males appearing in clusters about two weeks before the first females. Identify males by the sticky, pollen covered tubes in their centers. At the base of each female is a tiny, undeveloped cucumber. At this stage:
Work a 2-inch layer of organic compost into the soil around the plants. Top dress with an organic, nitrogen-rich fertilizer such as blood meal, applied at the label’s recommended rate. They’ll provide months of balanced nutrition.
Give your cukes from 1 to 2 inches of water (6 to 12 gallons for every 10 square feet of soil) weekly. Continue this through your harvest.
Protect the vines’ shallow roots with a 2-inch layer of organic mulch, such as shredded leaves or straw.
The Harvesting Stage
Knowing when to pick your cucumbers means the difference between baskets of sweet, juicy cukes and tough, bitter ones. Most are ready for picking eight to 10 days after pollination, with medium- or dark-green skin. Pick slicing cukes when they’re 7 to 9 inches long, pickling ones at 2 to 4 inches and burpless varieties when they measure 1.5 inches around.
Expert gardener’s tip: Exceptions to the medium-to-dark-green rule include yellow lemon and pale-green Armenian cukes as well as some white-skinned cultivars.