Cucumbers, depending on the variety grown, take 50 to 80 days to reach the harvest stage when planted from seed. Cucumber seedlings, purchased from garden centers, reach harvest stage one to two weeks earlier.
Since cucumbers require warm soil for successful germination, you should plant seeds outdoors at least two weeks after the last frost and when the soil temperature reaches at least 65 degrees Fahrenheit. For early harvest, start cucumber seeds indoors two to four weeks before the last expected frost. Cucumbers are ripe when the skin is firm and evenly green and the seeds inside are soft and underdeveloped. Harvest cucumbers frequently during the growing season to increase production and ensure the best quality.