Plant cucumbers at least two weeks after the average last frost date for the area. It is also acceptable to plant when the soil temperature registers at least 65 degrees Fahrenheit. Cucumbers are warm-weather crops that are easily damaged by frost.
To get a jump on the growing season, start cucumber seedlings inside up to three weeks before the transplant date, and provide a bottom heat source that is at least 70 degrees Fahrenheit. Place transplanted seedlings 12 inches apart, or direct-sow seeds 6 to 10 inches apart. Thin the plants to 18 inches apart when they are 4 inches tall. Cucumber plants need 1 gallon of water each week once fruit appears.