Many tall prairie species can get quite leggy and flop over by the time fall comes around. Heavy blooms on aster and goldenrod can be more then the sturdy looking stem can support. Species such as culvers root, iron weed, and joe pye are used to growing in dense patches of grass that help hold the plants up and hide the lower stem. Plants grow tall throughout the growing season to get their blooms above the rest and get the best pollinators. Native plants in gardens can be given summer trims to keep them from falling over when they are at their most beautiful.
Species that bloom in fall can be cut short early in the growing season. Good dates to remember for trimming the floppers is on Memorial Day and 4th of July. Any time between these two dates is fine for cutting back fall blooming plants and ideally cut them twice, once on each holiday.
Late summer bloomers can also be cut back before the flowers form. In late April and early May cut back culvers root, iron weed, joe pye, bergamot, coneflower, phlox, goldenrods, asters and many others. Before pruning always check that no flower buds are forming yet and then it is safe to cut back the plant.
Pruned plants will re-sprout and form a denser, multi-stemmed plant. Plants can be cut back one half to one third of their original height without stressing the plant. Just as when the deer prune a plant, the plant will bounce back. Be sure to leave several sets of leaves still on the plant. The trimmings can be dropped right at the base of the plant as green mulch. This also helps any hapless beneficial insects to find their host plant again. Plants cut back on different dates will have different bloom periods. For an extended bloom period leave some plants untouched and prune others on two separate dates. This is also a chance to sculpt a wildflower hedge by cutting plants lower close to the path and higher in the back.
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