How to Grow Viola Blackjack

Fill a 1-inch-deep seedling tray with seed compost or another sterile, nutrient-poor growing medium. Mist the medium with a spray bottle until it feels moist to half its depth.

Sow one seed per square inch. Press the seed into the surface of the compost. Spread a scant layer of compost over the seeds so they are barely covered. Spritz the compost layer to anchor the seeds.

Place the seedling tray in a refrigerator set to approximately 38 degrees Fahrenheit, or outdoors in a sheltered, frost-free place where temperatures stay around 38 F during the day. Keep the tray exposed to cold temperatures for two weeks.

Move the seedling tray to a warm, bright location after the cold stratification period. Place it near a large, south-facing window, under a fluorescent lamp, or in a heated greenhouse, depending on what is available to you.

Apply bottom heat using a propagation heat mat set to 70 F. Adjust the temperature to 58 F at night. Mist the seed compost frequently to maintain moisture at a 1/2-inch depth.

Watch for germination in two weeks. Transplant the seedlings into individual 3.5-inch starter pots filled with potting soil, once they produce two leaves.

Keep the individually potted seedlings under warm, bright conditions until after the last frost in spring. Water each plant whenever the soil feels dry in the top inch.

Move the young plants into the garden once the soil warms to 65 F. Space them 6 to 8 inches apart in a sunny bed with fertile, well-draining soil.