Propagation: Germinating buddleia davidii and butterfly weed in zone 10, 0 by

wrote:
Hi:
Buddleia davidii is easy to sow. I sow the seeds in fine seeding mix, cover lightly. Grow at 68F degrees. They should germinate in15 to 60 days. Usually it more like 15 days.

Asclepias tuberosa isn't as easy. They need stratification (cold treatment). My method is to use kitchen paper towel method:

Cut a paper towel in half. Wet it, then squeeze out excess. Open it and fold in half and place seeds in one corner. Fold the napkin over the seeds twice until you have a square. Place in ziplock baggie. Zip the top, leaving an opening to blow air in to create a balloon. Quickly close the bag. If the bag don't hold the air, open and rezip again. Sometimes these bags don't zip easily if the runners don't match. Once done, place the baggie in the refrigerator for 3 weeks. After that time, take it out and place the bagggies where it is warm. Often the top of a refrigerator is warm.

Check on the seeds every 2 days or so. As soon as you see radicals (tiny roots) emerging, sow the seeds in little pots or seed flats 1/16" deep. Make sure the root points downwards. I place the seed level with the soil, roots pointed down, then lightly cover with soil. I use a pair of tweezers to pick up the seed with. When you see growth break the soil, give them light.

I sow all my perennial seeds that can be finger held this way with more germination than straight into soil. Also I don't oversow. Tiny seeds can be mixed in fine peatmoss, moistened than place in the baggie.

Not all perennials need stratification so don't need to be placed in the refrigerator.

My butterfly weed seeds are still in my frig, so no photo. However, I am posting a photo of Hibiscus mosch. These sprouted in 2 days with the moist paper treatment. The seeds were nicked first, then soaked overnight in hand hot water. You can see the tiny radicals. I planted these shortly after the photo was taken.