Grow Guide: Preventing Weeds
Q: Last spring I had a terrible time with weeds in my lawn, and spraying them damaged some of my grass. I was told to put down a weed preventer in the fall. Is now the best time?
You were given pretty good advice, but because I see you live in the Southeast, it is too late for this now. I have some good news for you, but first a little overview. And of course this overrides my personal appreciation of how many “weeds” are also pretty little spring wildflowers that host butterflies and bees early in the season!
The idea for weed prevention, which works only on weeds that sprout from seed (henbit, chickweed, annual bluegrass, burr-weed or “stickers” and some clovers), is to apply a “pre-emergent“ herbicide before the weed seeds sprout in the fall. Once the seeds have sprouted -- which in the southern part of the country happens generally in September and early October -- it is too late to apply these products. Northern gardeners can apply these materials in August for pretty good control, but need to keep in mind that if they want to put out new grass seed in the fall, pre-emergent herbicides can also keep their grass seed from sprouting.
Another downer is that a lot of your weeds are probably “perennial” weeds that come up from underground parts that can live for years, including pink oxalis, clover, dandelions and violets. Though these are summer weeds up North, they grow best over the winter and spring in the South. The good news is that you can treat all of them in your Southern lawn during warmish weather in mid winter, when weeds are actively growing but the lawn is dormant and less likely to be injured.
Garden centers carry a variety of “post emerge” herbicide liquid sprays for controlling these weeds, and if you apply them after a hard frost or freeze, when your lawn is not growing but the young weeds are, you can kill most of them well ahead of time. This is far more effective than waiting until spring when the weeds are larger, tougher, already going to seed, and your lawn is starting to green-up -- making it more susceptible to herbicide damage. By the way, while “weed and feed” products work well on northern type grasses, they are generally not a good combination for southern turf grasses. Better to treat weeds separately from fertilizing. No fertilizing until after the grass has greened up and been mowed a time or two in April. If you need more specific information (product names, lawn care calendar, etc.), please contact your county extension service office, which has tips custom made for your state.
Gardening expert and certified wit Felder Rushing answers your questions and lays down some green-wisdom. You can get more of your Felder fix at www.slowgardening.net.