By Kathleen Cue, Nebraska Extension Horticulture Educator
“What is this grass growing in my flower bed?” is a question I hear quite often now. Rolling the stem between my fingers quickly determines this isn’t grass at all but the infamous yellow nutsedge. Sedges are grass-like perennials that have triangular shaped stems. If they grew at the same rate as turfgrass, many lawn owners would be OK with nutsedge growing there. Unfortunately, high heat and abundant moisture foster fast growth that easily outpaces the height of Kentucky bluegrass and fescue. Yellow nutsedge is a particular problem in new flower beds and shrub borders if the previous space was occupied by turfgrass. Dense lawns suppress the growth of yellow nutsedge and, once the turf is removed and landscape plants installed, yellow nutsedge can show up throughout.
The use of “nut” in yellow nutsedge’s name comes from the small tubers, called nutlets, found at the end of roots. The presence of these nutlets helps to explain why the plant is so hard to manage at this time of the year. Removing yellow nutsedge by hand-pulling ensures nutlets will be left behind. Once each nutlet begins to grow, where once there was one plant, now there are many. Herbicides used now will also be effective at eliminating the parent plant, but bear in mind herbicides do not translocate to the nutlets, so again, where once there was one plant, now there are many. This isn’t to say we can’t hand-pull or use a herbicide, it just means diligence will have to be exercised to stay after new plants by repeating previous steps.
June 21 (the summer solstice) is the dividing point from when yellow nutsedge is relatively easy to manage to when it becomes a chore. Prior to June 21, plants have not reached the maturity necessary to form nutlets. Lawn herbicides containing the active ingredient Halosulfuron (Sedge Ender™, Sedge Hammer™, and Halosulfuron Pro™) applied before this date will be the most successful at managing yellow nutsedge in lawns. In gardens and borders, yellow nutsedge can be hand-pulled or spot sprayed with herbicides containing glyphosate, being mindful to shield desired plants.
From June 21 onward, the nutlets of yellow nutsedge are a tenacious survival mechanism that requires diligence (or acceptance) on our part to manage yellow nutsedge in our landscapes.