Extension

As Oklahoma homeowners patiently wait for the landscape to green up and put plans in place for their spring and summer gardens, they also need to plan ahead for weed control. Nothing spoils the look of a landscape or garden bed quite like a bunch of weeds.

One of the most effective tools for preventing annual weeds is the proper use of pre-emergence herbicides. These products are designed to prevent weeds from growing. They work by forming a barrier in the soil that disrupts seedling growth as the weeds begin to develop. Homeowners can apply herbicides themselves or hire a licensed applicator. With spring just around the corner, now is the time to act. Now through the end of March is the ideal time to apply pre-emergence herbicides to control summer annual weeds. For those who like to plan ahead, early September through October is the optimal time to treat for winter annual weeds.

Products purchased at the local gardening store last four to six months, depending on the product and the weather at the time of application. A second application may be required to provide control all season.

First and foremost – read the label directions for best results. The herbicides are applied to the soil, typically as dry granules, but some are available in liquid form. Gardeners will get better penetration and distribution of the herbicides if the soil is tilled before application. If there is no rain forecast within 48 hours of application, irrigate the soil with up to 1 inch of water to activate the product.

Because weeds can build up resistance when the same herbicide is used year after year, gardeners may need to change products from time to time. Also, avoid using herbicides in areas where you plan to grow plants from seed or in newly seeded lawns. These products affect many germinating seeds, not just weeds.

Pre-emergence herbicides are great tools for controlling weeds but should be part of a broader lawn and landscape care program that includes mowing and fertilization the lawn and using mulches in landscape beds and gardens. In some cases, post-emergence weed control is also needed.