From the Ground Up: Sping Weed Control

crabgrass

by ISU Extension & Outreach Linn County Master Gardener Jean Murray

All gardeners want to get a head start on weeds in lawn and gardens, but before you jump head first into weed control, take some time to evaluate your individual situation.

If your lawn typically looks pretty good and has few weeds, you may not really need to deal with weeds.  If your lawn has a history of crabgrass infestation, you may want to apply a pre-emergence herbicide before the crabgrass has a chance to germinate.  This normally occurs when soil temperatures near 60 degrees.  Don't try to control dandelions and broadleaf  weeds until the soil warms up; the herbicide will burn off the shoots but may not kill the root system.

In the garden, you can use one or more of these common methods to control weeds: (1) cultivating (hoeing and rototilling) and hand pulling, (2) mulching, and (3) herbicides.  You can control most annual weeds with cultivation and hand pulling, but it often takes repeated cultivation to kill many perennial weeds.  Don't cultivate too deeply in your perennial bed, since the roots of many plants grow near the soil surface and you can damage those roots. Plus if you cultivate too deep you run the chance of bringing up deeply buried weed seeds to the surface where they can germinate.

Now is a good time to get started on weeding; smaller weeds are easier to pull than larger ones.  First, clear mulch and plant debris from last year off your beds so you can see those weeds. Make sure they are weeds and not your favorite hosta!  Vegetable beds can also be cultivated in April, before you begin planting most vegetables.

Mulch offers another effective weed control method, and come in two general varieties: organic and synthetic.  Grass clippings (from chemical free lawns), shredded leaves, and straw are excellent organic mulches for vegetable gardens and annual flower beds.  Apply 4 to 6 inches of these materials in early June after the soil has warmed sufficiently.  If you put down these mulches when the soil is still cool, you may slow down the growth of plants. 

Wood chips, shredded bark, and ground corncobs are excellent mulches around your trees, shrubs, and perennials.  Apply 2 to 4 inches of material, but don't mound mulch up too high on tree trunks.

If you choose, herbicides are helpful at controlling the most stubborn weeds but no single herbicide works in all garden and lawn areas.  Different herbicides control different weeds and some should not be used on or around most vegetables.  Be sure to read labels carefully and ask questions at your lawn and garden center.

If you have questions, call ISU Extension Linn County Master Gardeners at 319-447-0647, from 10am-Noon weekdays. Or send an email with your question to eward@iastate.edu.

 

photo via Illinois Extension

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