I am a huge fan of milkweeds due to their special attraction not only to monarch butterflies but also to a considerable list of other insects that are milkweed specialists, and some generalists who use milkweeds as a community to forage in. But the problem is that those of us that own hay fields will cut the grass including the milkweeds once or usually more per year, slaughtering the marvelous milkweeds. However I have come up with a compromise that I think both feeds the cows, and preserves the milkweed community. See what you think of my solution.
My plan is to cut the grasslands only once per year and that is in mid to late June in our location here in the SW Virginia mountains. This serves not only to harvest the grass for use in fodder but removes woody vegetation that invades the grasslands, and removes a layer of cold-season grasses (such as fescue) that are primarily exotic to this area. This releases the warm-season grasses and allows them to grow and produce a crop of seeds by Fall for use by native birds. But you may ask what about the milkweeds and their fate? It appears to me that this regime may actually be beneficial to the milkweed community in the following way. I retain a certain number of fields that are not cut except very occasionally (they are burned every three years in late Winter) and which have natural populations of milkweeds (in this case mainly the common milkweed, Asclepias syriaca). The fields that were cut this year on June 17 began about seven weeks later in early August to produce a wonderful crop of milkweed flowers, while the uncut milkweeds are setting seed and are no longer blooming. The leaves of the uncut milkweeds are old and tough whereas the cut and regrown milkweeds have young tender leaves. Thus my single-cut method of harvesting hay fields stretches out the milkweed season but does not obliterate it, as would happen if the fields were to be harvested a second time, a common practice among farmers to maximize hay production. Also I have noticed that the monarchs often do not arrive in this area in time to fully utilize the naturally cycling milkweeds, and indeed seem to use the "second crop" milkweeds extensively.
Some illustrations of the re-grown milkweeds are shown in photos of an adult monarch gathering nectar from a "second crop" flower, of a female yellow morph tiger swallowtail also nectaring on a re-grown plant, and a monarch caterpillar feeding on a re-grown leaf. Surely there is much yet to learn about the characteristics of milkweeds that are cut and then sprout again- do they provide proper food at tolerable levels of toxins, and in a timetable that is appropriate? Certainly it appears from my observations that this is a win-win situation that can preserve the habitat of many species that depend on milkweeds while also providing some income for the farmer. Of course subsequent hay cuttings must be sacrificed for the pleasure of observing and fostering the milkweed animal community, and providing enhanced food and cover for birds in Fall and Winter.
So many puzzles and so little time! So get out there and check out the milkweeds and their fascinating inhabitants.