Friends of Las Vegas National Wildlife Refuge


   asclepias syriaca L.

The seed can grow almost anywhere in North America. When you are ready to plant, place the seeds 1/8” below the soil surface. You can use a deep pot since most milkweeds have long roots. Don't plant the seeds too deep, because they need plenty of light and warmth to germinate and grow (at 70 degrees within 14 days). Keep the seedlings moist for the first three weeks after they sprout, then transplant to larger containers with quality soil if necessary. You can lightly fertilize them after the seedling stage, using a regular flower fertilizer. Cutting off the top of the plants after they reach 8-12" creates more stalks and more leaves. It takes about two months before the plant is large enough for caterpillars to eat. When the leaves have been eaten, simply cut the plant off about three inches above the soil or just above the lowest branching of the stalk and the plant will grow back fuller and create even more food for Monarchs.

Warning: one caterpillar will eat 20+ large leaves so make sure you have enough plants to support the number of caterpillars you have, or they will starve.  For ground grown plants we usually start seeds in nursery trays.   When the seedlings have at least two sets of leaves we transplant to larger containers with good drainage. The seedlings have long roots and must be kept moist so transplant and water soon after. We suggest you purchase the best potting soil available as this will greatly accelerate the growth of these seedlings. Growing times will depend on milkweed variety and your location. 7-14 days is typical for germination.

When the seedling is about 30 days old (from seed), it should be pinched. That means the tiny new leaves at the top of the plant should be cut off. This cutting forces the plant to begin new growth from each joint. A plant on the right about 40 days old should have 5 growth stalks, which will provide far more leaves for your caterpillars and gives you a much fuller bush like Milkweed. Once the plants get going, the growth is dramatic from week to week. Water only when the soil gets dried out or the plants begin to wilt after the seedling stage. When the roots completely surround the inside of the pot it is time for a larger container with good drainage. Good luck. 


Other Resources  University of Minnesota Monarch Lab


NABA  (North American Butterfly Association)

Monarch Watch


Native Plant Society of New Mexico


Seeds and Plants

Plants of the Southwest

3095 Agua Fria, Santa Fe, NM 87507


6680 Fourth St. NW, Albuquerque, 87107


Applewood Seed Co.,

Arvada, CO,

303 431-7333


Santa Ana Native Plants

2 Dove Road, Bernalillo, NM 87004

505 867-1322


Aqua Fria Nursery

1409 Aqua Fria St, Santa Fe, NM 87505

505 983-3593

Friends of Las Vegas (New Mexico) National Wildlife Refuge

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