Extension

What gardener doesn’t like saving time? But some time-saving measures, such as using an herbicide and fertilizer combo, may be good in theory but not a good solution in all situations.

 

One problem with a weed and feed combo is that the timing for an herbicide application and a fertilizer application aren’t usually in sync. Some weed and feed products contain preemergence herbicides that control weeds as they germinate and are best applied before late February, depending on weather conditions. Fertilizer applications for warm-season grasses such as bermudagrass shouldn’t go on until early May. The issue is fertilizer and herbicide need to be applied at different times, so using a weed and feed combo blend on bermudagrass in late winter/early spring isn’t advised.

 

Another issue is the selection of weed and feed blends is quite limited compared to shopping for just a fertilizer. Fertilizer formulations are much more diverse because fertilizer companies make many more types. Most companies that produce weed and feed products only make one type, and typically don’t consider special nutrient needs that may have shown up in a soil test, such as needing more phosphorus. In addition, the types of weed killer used in combination products is limited compared to the many products available without fertilizer.

 

There’s more of a chance of over-application or misapplication of weed killer. Gardeners must take extra care in applying herbicides because tree and shrub roots can also absorb these products. The labels on many herbicide products state they shouldn’t be applied where roots of desirable trees and shrubs are growing. There’s no way to apply an herbicide to turf areas with trees growing nearby. Using separate products is the best answer.

 

In addition, overthrow of the product into areas that have sensitive plants can be an issue. This happens when the wrong equipment is used, such as a broadcast spreader instead of a drop or gravity spreader. It just makes sense to apply products separately to allow for more accurate rates of distribution.

 

And finally, why treat healthy grass with something it doesn’t need and could potentially weaken it? Keep in mind that weakened turfgrass is more likely to have weed problems. Spot-treating problem areas is much more effective and potentially less costly.

 

One of the best ways to address weed problems is to start with improving the turf. A vigorous, healthy lawn can choke out most weeds. For more turfgrass management practices, check out Oklahoma State University Extension’s Lawn Management in Oklahoma fact sheet.