How to Grow Milkweed
HOW: The first step in growing any species of milkweed is to acquire seeds that are native to your area. This means either purchasing seeds from a distributor like Grow Milkweed Plants or collecting them from roadsides and gardens where milkweed has gone to seed. The latter options are best because collecting seed that is adapted to your area will have a better chance of survival since they are adapted to climate and soil conditions in your region.
Once you have collected the seeds, remove the floss from seeds before either planting them directly in the ground or cold-stratifying them yourself. This can be done by placing seeds attached to floss (or fluff) into a paper bag and placing several coins in the bag. Shake the bag several times then look inside. If the seeds are still attached to the floss, shake again until almost all of the seeds are separated. Hand separating seeds from floss is time-consuming and frustrating, so this saves time and makes life much easier!
WHEN: In most areas, seed collection typically happens in the fall. Note that to improve seed viability only collect seeds from pods that have split open and have deep brown seeds. If you collect them too early, you may wind up with a lot of wasted seeds and no milkweed plants. Planting seeds around Thanksgiving, ideally before the first frost, is a good rule of thumb.
Preparing & Planting Seeds
Now that you have mature seeds with the floss removed, the next step is to determine how you are going to get the seeds ready for planting. There are two methods of seed prep, and it is up to you how you choose to do this. These methods will differ if you live in a warmer climate.
1) Cold Stratification Outdoors: Stratification is a natural process that promotes seed germination by breaking the seed dormancy. If you live in areas where there are freezing temperatures, you can rely on mother nature to do the stratification for you. Simply remove all mulch, rocks, weeds and importantly, invasive species from the area you are planting. You can put a hole in the soil (approximately up you your first knuckle) and place an individual seed in the hole and cover it up, or you can scatter the seeds on the surface of the soil and cover with moist soil. Either way, you should make sure the seeds are planted at least 3-4 inches apart to avoid overcrowding. In the spring, your seedlings should appear in your garden with no work on your part other than the planting of the seeds the previous fall.
2) Cold Stratification Indoors: If you choose to collect seeds and undertake cold stratification yourself, you will need seeds, soil and space in your refrigerator for several months to do this.
There are two methods for growing milkweed in the spring if you start them indoors:
1) Planting cold stratified seeds once the threat of the last thaw has passed
2) Starting the stratified seeds indoors and planting the seedling after the threat of the last thaw has passed.
If you choose to start seeds indoors, once the floss is removed, place seeds between two damp (not wet) paper towels and place them in a Ziplock baggie or a reusable Tupperware container. Make sure to label the species you are starting indoors. Most species require at least 30-45 days in the refrigerator to prepare them for germinating. Remove them from the refrigerator and plant them in small pots. Moisten the soil before adding seeds. Plant one or two seeds per pot in peat potting mix and cover with 1/4" of soil. Water only enough to keep soil damp, not soggy. Overwatering can cause a fungus to grow.
NOTE: MILKWEED DOES NOT REQUIRE PESTICIDES OF ANY KIND! As a matter of fact, pesticides used throughout the country in farming and private gardens is part of the reason we are losing our milkweed species at alarming rates. Please be part of the solution, not part of the problem and resist using any type of pesticide in your yard or garden.