Deadheading milkweed for more blooms?

[aphid]

I noticed swamp milkweed, along the ditches of highways here, that are in bloom right now. Mine at home have long since bloomed and developing seed pods. The ones along the highway must have been mowed down earlier in the year. It got me to wonder how I could deadhead my milkweeds to keep them blooming more.

Has anyone got experience doing this, and with which species?

(http://www.butterflysocietyofva.org/blank_page_2.htm) mentions "With early seed pod removal, some Asclepias will rebloom."

When would a milkweed need deadheaded? Just the expired blooms? or possibly the whole branch holding the blooms?

[Mona Miller]

If you want it to reflower, then take off the whole flower head down to just above a leaf node (where the leaf is attached). I leave some of the stems to flower and set seed and then trim the others so they rebloom. Swamp, butterfly weed, common, many can be deadheaded. I cut them back too so that there is new tender growth for those fall Monarchs traveling through. I dug up some common milkweed rhizomes and replanted them in pots. Some of them have blooms on them now.

[Paul Cherubini]

Most milkweeds are perennials with underground rhizomes that survive through the winter. These can be deadheaded, but you should only do it once per season, otherwise you'll weaken the whole plant including the rhizome and so next year's plants will be smaller.

The non-native Asclepias currassavica can be cut back multiple times each season without weakening the plant and that's why commercial monarch breeders like to grow it. But currassavica is a tropical, frost sensitive species that doesn't have foliage or roots that can survive subfreezing temperatures so each spring you have to start it from seed (unless you grow it in a heated greenhouse over the winter).

[Mona Miller]

I have several monarch caterpillars on my swamp milkweed right now who are deadheading it. They do this several times a season.