Cleome Germination

When to Seed

• Start cleome seeds in the spring. Plant indoor seedlings nine weeks before the last expected spring frost. Wait until all frost has passed and for the temperatures to warm sufficiently before direct-seeding the cleomes in outdoor beds. Cleome seeds germinate best at temperatures between 70 and 75 degrees Fahrenheit, and they do not sprout in cold soils.

Indoor Seed Starting

• Plant the seeds in flat or individual pots filled with a moisten soil formulated for seedlings. These soils are sterile and have a fine texture that encourages proper seedling growth. Plant the seeds on the soil surface and cover them with a 1/8-inch layer of soil. Space the seeds so there are approximately two seeds per square inch per flat, or sow two to three seeds per pot. Cleome seeds require light to germinate, so place the pots in an area in bright, indirect light after sowing. Keep the potting soil evenly moist at all times during the germination process.

Direct Outdoor Seeding

• Smooth the soil surface in the garden bed with a rake, breaking up any large soil clods. Choose a bed that receives eight hours of daily sunlight to ensure the cleome plants receive the necessary light both during germination and after. Sprinkle onto the soil surface, spacing the seeds 4 to 6 inches apart. Press on the seeds lightly so they are in full contact with the soil but do not bury them. Mist the soil bed with water daily to keep it moist.

Germination Times

• Cleomes germinate within seven to 14 days when they are provided with enough light, moisture and warmth. Indoor grown seeds often germinate more quickly as its simpler to provide even amounts of light and warmth. Cooler temperatures or a period of overcast weather can slow down germination of outdoor planted seeds. Always start the seeds indoors if you want to ensure you have enough of the plants sprout for your garden needs.