While warm temperatures are required for growing, cucumbers require a relatively short season–55 to 60 days from sowing to harvest. In long-season regions, you can plant successive crops. In cool or short-season regions, choose the warmest time of the year for growing cucumbers.
Here are a few tips for growing cucumbers:
• Cucumber sex. Cucumbers are either monoecious or gynecious. Monoecious plants have both male and female flowers on the same plant; the first flowers that appear are male or non-fruiting; fruiting female flowers appear 7 to 10 days after at the end of shoots. Gynecious cucumbers have only female flowers. They require a male flower on a nearby plant for pollination. (Packets of gynecious cucumber seeds commonly contain pollinator-plant seeds; these seeds will be color coated for identification.) Cucumbers are pollinated by visiting insects or birds. (Most cucumber varieties are monoecious.)
• Sowing and planting. Cucumber seeds will germinate in as little as three days when the soil temperature is 80° to 90°F. Sow cucumber seed indoors about three weeks before setting seedlings into the garden. Start cucumbers indoors in individual pots so that the roots are not disturbed at transplanting. Set out cucumber starts when the garden soil temperature is 70°F or greater. You can speed garden soil warming by covering the planting area with black plastic mulch or by using mounds or raised rows to grow cucumbers.
• Spacing. Plant cucumbers in full sun and set bush cucumbers 18 to 24 inches apart and vining varieties at least 24 to 36 inches apart in rows 3 feet apart. Cucumbers like well-drained roots so planting on mounds is a good idea. Set three plants on mounds 3 feet across; space mounds 6 feet apart. Set trellises or pole supports in place before you plant seedlings. To prevent diseases, air circulation around plants is important.
• Protection. Cucumbers do not like chilly weather or chilly soil. They will die back with even a touch of frost. When night temperatures fall below 65°F protect cucumbers with floating row covers.
• Water. Cucumbers are 96 percent water. For best growth, they require uninterrupted moisture from sprouting to harvest. Water seedlings well, and keep soil moist throughout the season especially when flowering and fruiting. Bitter and misshapen fruit are the result of water stress. To stem moisture evaporation, cover the soil with black plastic or thick compost mulch after planting.
• Feeding. Cucumbers are heavy feeders. Add plenty of aged compost or manure to the planting bed in advance of sowing. Before you plant, place aged compost or manure at the bottom of each planting hole and throw in a buffer inch or two of native soil. (An all-purpose organic fertilizer, 10-30-10 can be used–follow the label directions.) This will get plants off to a strong start. Apply compost tea or manure tea at transplanting or two weeks after seedlings emerge. Feed again with compost tea in three weeks or when the first flowers appear. When the first fruits set, water each plant with compost tea or side-dress each plant with a shovel full of compost. If leaves are pale, give plants a dose of fish emulsion. But be careful not to give squashes too much nitrogen; nitrogen will increase leafy growth but cut fruit yield.
• Prune. Cucumbers easily grow on trellises, cages, fences, or poles. A 4-foot-high wire cage is about the right size. When vines reach the top of the cage, trellis or fence, pinch out the fuzzy growing tip. This will allow plants to spread laterally. Fruits that grow curved on the ground will grow straight when hanging from supports.
• Problems. Cucumbers are susceptible to diseases and pests. Squash beetles and striped cucumber beetles can be regular visitors–feeding at night. (Cucumber beetles are attracted to the bitter compound in the skin of many cucumber varieties.) Handpick these pests in the early morning or plant varieties that don’t have the bitter compound–‘Holland’, ‘Aria’, and ‘Lemon’ are good choices. Cucumbers can also be plagued by wilts and powdery mildew. Plant disease resistant varieties: look for letter codes indicating diseases resistant, leaf spot (LS), anthracnose (A), wilt (BW), mosaic (M), scab (S), and mildew (DM).
• Harvest. Harvest cucumbers when they are green, firm, and moderate size. Harvest slicing cucumbers when 6-10 inches long, pickling (sweet pr baby dills when 1-6 inches long, regular dills when 3-4 inches long. The best rule is pick cucumbers as soon as they reach useable size. Cucumbers left on the vine too long will become seedy and bitter. Cucumbers that are dull, puffy, and yellowing are past their prime. A prompt harvest will allow plants to set new fruit. Fruit left to mature on the plant will completely stop the set of new fruit.