Garden In The Koop Painted Serpent Cucumber Seeds Cucumbers are a subtropical plant in full sun with space to grow-a trellis helps if space is limited Cucumbers are happiest around 70 degrees so plant them in late spring or early summer when there is no risk of frost Grow your cucumber starter plants indoors up to 2 weeks before planting; Transplant after risk of frost has passed; In 70 days you can eat the cuke