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What to do with Winter Weeds

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Weeds in the lawn and garden are always an annoyance, but winter weeds are especially irritating. Their lush green is glaring against dormant brown lawns and mulched brown gardens.

The winter annual weeds we see now started to germinate in September. They grew slowly until January when their growth rate surged. They flower generally through March and beyond. The timeline alone is evidence of the need to adhere to the four times per year preemergence schedule.

This year the winter weed scenario includes Hurricane Matthew’s input. High winds and, especially, flooding left a lot of weed seeds and plant parts in our yards. We’re just meeting some of those new weeds in our lawns and gardens now in February.

As you may know, preemergent needs to be watered into the lawn, but a hurricane is not the way to do it. The early October battering rain from Matthew served to leach preemergent (and nutrients) out of the soil. The result was reduced efficacy of the September preemergent treatment.

Whether flooding from the hurricane was just your swale or retention pond overflowing its bounds or full scale inundation, water brings weed seeds from your neighbor up the street, the community up the waterway, and any field or wooded area it washes through.

A weedy lawn indicates inadequate conditions for growing grass. That may be caused by incorrect pH, lack of nutrients, too much moisture, insufficient water or lack of sun. To improve your lawn the first thing to do is find out the pH and nutrient levels of the soil with a soil test. Then amend your soil based on the results of the test.

The best way to suppress turf weeds is through proper lawn maintenance. However, weeds are opportunists. They love areas where they do not need to compete for water, light and nutrients. An under- or over-watered lawn encourages weeds, so does an over-fertilized lawn. But weeds also invade properly maintained dormant turf and well mulched gardens. Hurricane Matthew is a good example of how that can happen.

Prevention is critical to controlling weeds. Cover bare areas with two to three inches of mulch. It will help prevent light from reaching weed seeds and thereby limit the number that will germinate.

Hand pull young weeds. Their root systems are small and can be completely removed. The best time, of course, is when the soil is wet—the green above-ground part and the entire root system come out more easily.

Do not allow weeds to bloom. They produce thousands of seeds. Some annual weed seeds can remain dormant and viable in the ground for up to 50 years. They need only sun and water to germinate. Excavation for houses, commercial buildings and roads, cultivation of a garden and even fire expose seeds for germination. Whenever you turn over your soil or simply dig a hole you expose thousands of weed seeds, and a number of them germinate.

When an infestation of weeds is so serious that you must use a chemical for control be sure to identify the weed and select an herbicide right for that plant. Some weeds are resistant to certain chemicals. Don’t assume that an herbicide that kills broad leaf weeds will kill every type of weed.

Read and follow all label directions. For weeds in your lawn make sure the product is safe for use on your type of grass. Pay attention to proper timing—you can injure your turf if you don’t. If the label tells you not to use a chemical near trees and ornamentals follow directions. Abide by personal safety precautions.

Winter weeds include both annuals and perennials. Some common winter weeds you may find in your yard include annual bluegrass (poa annua), Carolina geranium, common chickweed, dandelion, dead nettle, Florida betony, henbit, oxalis and wild garlic or onion.

Come spring and summer we will see what new summer weeds Matthew left in our yards. Even though weather, wildlife and nursery plants will continue to supply our yards with seeds, weed prevention practices will help reduce future crops.

Reach Debbie Menchek, a Clemson Master Gardener, at dmgha3@aol.com.

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