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Monday - November 02, 2009

From: Burnet, TX
Region: Southwest
Topic: Butterfly Gardens
Title: Propagating milkweeds for a monarch butterfly habitat
Answered by: Nan Hampton and Sean Watson

QUESTION:

I am planting a monarch habitat in Burnet, Tx with Antelope horns, Green milkweed, and butterfly weed. Should I plant in fall or spring??? Should I use cold moist stratification for 3 months at 40 degrees in sand on all three types of milkweed or just antelope horns. Is is better to plant in peat pots or clay pots over the winter and then transplant in spring around March???

ANSWER:

Mr. Smarty Plants assumes that the following are the milkweeds you want to grow in your monarch habitat:

Asclepias asperula (antelope horns), Asclepias viridis (green antelopehorn), Asclepias viridiflora (green comet milkweed) and Asclepias tuberosa (butterfly milkweed)

To learn the best method for propagting these, Mr. Smarty Plants consulted Sean Watson, the Wildflower Center nursery manager who offered this advice for you:

I have never had trouble with milkweeds germinating (no stratification needed). If you use the freshest seed possible, sow them in a tall pot or seed flat with deep cells to start them (room for taproots), and keep them moist until you see the first pair of true leaves, you should have great success. You could then transplant them into a larger clay pot to overwinter (clay pots would be best since they breathe) and then transplant them into the ground in the Spring. It would be best to cover the flat/pot with a clear plastic container to act as a greenhouse if you want to start them now. After transplanting them into the clay pot and/or ground, water in thoroughly and then allow to dry out slightly between watering from that point until established (they like to rot once the taproot begins to get larger/fleshy since at this point the roots hold more water so the plant needs less). Just make sure the final site is well drained.

You would have much better success, however, if you wait until February to start them so you can transplant them out in early spring (that way the root system is able to develop more before the next winter). In either case, making a mini greenhouse will allow for greater germination percentage because of increased humidity (I use an aquarium at home). The most important thing seems to be giving the taproots room to grow. ALL milkweeds I have ever grown have always grown much better in the taller gallon pots/or tall tree pots than the shorter, square 4-inch pots. They seem to grow much better when started in early to mid spring (i.e. they love heat).

Asclepias asperula

Asclepias viridis

Asclepias viridiflora