To control size, cut back as much of the new-ish growth as desired while not in flower (April-ish). Do not prune in late spring as you will remove forming buds which will form this season’s blooms. After flowering, leave spent flowers to dry into red / brown clusters. This is part of the desired look of native buckwheats. The seeds develop into valuable wildlife food and help shade the plant in the summer heat (1). “Deadheading” buckwheats would be tedious and time consuming and would take away much of what there is to love about this plant. Keep things easy and don’t worry about it (S). If desired, remove dried seed heads beginning in mid-September and into the fall (1). Older plants that look like they need refreshing can be cut back hard into older wood in November, although there is always a possibility they will not regrow. Expect new growth to emerge within a few weeks (1). A more conservative option is to cut back hard, but only cut back above the lowest few sets of leaves. This may not be as satisfactory aesthetically, but may be less of a risk of plants dying (3, S). If desired, they can also be lightly headed back in fall just to clean up form and encourage denser growth (7). References