How to Grow Clematis Helios From Seed

Fill 3.5-inch seed-starting pots with a soil mixture composed of 3 parts loam and 1 part perlite. Press the soil surface with your fingers to even it out.

Place three or four seeds on the soil mixture in each pot. Press the seeds onto the soil to anchor them. Spread a very thin, 1/16-inch-thick layer of soil over the seeds.

Mist each seed-starting pot with water from a spray bottle to settle the soil. Keep misting the pots until the soil feels moist just beneath the surface. Maintain light moisture in the top 1/4 inch of soil while the seeds germinate.

Set the seed-starting pots on a propagation mat. Adjust the temperature on the propagation mat to 72 F during the day. Shut off the propagation mat at night, or adjust it to 55 F if you live in an area where nighttime temperatures dip below 50 F indoors.

Watch for germination in 15 to 20 days. Thin the seedlings if all of the seeds germinate. Remove the weaker, less vigorous sprouts from each seed-starting pot until only one remains.

Keep the seedlings in a sunny, cool spot indoors where temperatures stay around 68 F during the day. Move the seedlings to a sheltered spot outdoors after the last frost in spring so they will acclimate to normal weather conditions.

Transplant the seedlings into a permanent bed as soon as soil temperatures reach 68 F and nighttime air temperatures stay above 50 F. Space the seedlings at least 18 inches apart.