milk weed seeds

Asked June 1, 2017, 12:50 PM EDT

I am starting my milk weed seeds in a sterile medium. After they sprout can I plant them in regular potting soil or do they have to grow to maturity in the sterile mix? Thank you Patti Wolff

Jackson County Oregon

1 Response

Patti; seeds are started in a sterile medium so the little seedlings do not develop a condition known as "damping off". which is a fungus that attacks the stems of seedlings in a non-sterile potting situation. (Seeds planted directly in the ground usually do not develop this problem.). When you use a sterile medium, you would normally transplant the seedlings when they develop two sets of true leaves--those are the leaves that appear after the first set of rudimentary leaves known as cotyledons. You would transplant into a good quality potting mix, which usually contains some fertilizer and some moisture holding material like peat or coir. It normally does not contain garden "dirt".. Then you would transplant again into your prepared garden bed when the seedling reaches a size that will sustain the plant's functions of taking up water, taking in sunlight, and making sugars. Now let's talk about milkweed. We assume you are trying to attract monarch butterflies, and are using seeds of one of the native varieties. They are notoriously difficult to transplant because they develop a long taproot. Nancy Bubel, author of The New Seed Starters Handbook suggests that you transplant the little seedlings into pots that are tall and narrow--you can obtain some plastic seedling 6 paks that have especially deep root areas. Then, as soon as the plants look sturdy enough to survive, harden them off (expose them gradually to the outside conditions by taking them in and out of shelter for an increasing length of daylight and sun), and plant them in a deep hole so that the root stays straight. Marie Sperka, author of Growing Wildflowers suggests trimming the tiny root to 4 inches so that feeder roots will develop faster.. As you might surmise from this answer, it is probably easier to start the seeds in your garden bed from the beginning! Plant in full sun and well-drained soil--they cannot tolerate standing water. Like most wildflowers, they are not picky about soil as long as it is in an area where they would normally grow wild, such as much of the Rogue Valley! One further caution:: do not mulch the new plants as they can develop crown rot. Good luck with your project and enjoy the butterflies! .