Many common lawn weeds are best controlled in fall.
Some of these weeds are perennial, but many are winter weeds like henbit, chickweed and bittercress that germinate in late summer and early fall, make a little growth, and then stop for the coldest part of the winter. Then, they take off in early spring as the days get longer and the soil starts warming.
They respond to herbicides very well at this time of year. While we suggest spot treating weeds with a liquid formulation to minimize herbicide use, a fall application of a ‘weed and feed’ fertilizer may be appropriate in some situations.
There can be several advantages, which include the following:
w Fall is the preferred time to fertilize cool season grasses, so we are killing two birds with one stone, assuming there are enough weeds to justify a treatment. Again, spot treatment will many times take care of the weed problem. Remember if you keep your turf cut high, you are denying weed seed the opportunity to germinate, lacking the sunlight needed.
w Some of these weeds will flower and reseed themselves in the early spring before we have a chance to mow or make a spring weed treatment. Again, use herbicides only where weeds are a real problem. An occasional weed isn’t a problem. A healthy stand of turf can keep the number of weeds at bay.
w If you accidentally throw some ‘weed and feed’ granules into the flower or vegetable garden, the herbicide will break down before spring.
w There also is less chance of injuring other ornamentals if we accidentally over-apply or spill some of the product.
There are few points to remember when recommending fall fertilization and the use of herbicides. Weed and feed products are usually sold in 20-pound bags intended to treat 5,000 square feet.
Directions for all popular spreaders are on the product label, and results should be fine if they are followed. Homeowners should not take an entire 5,000 square foot bag and put it all on their 2,500 square foot lawn. This can cause more harm than good.
When you double the fertilizer, you also are doubling the herbicide rate, which can do irreparable damage to some shrubs, trees and turf. Over the years I have seen examples of injury to trees and shrubs caused by just this type of ‘fertilization.’
Also, based on recent research, we should probably discourage late fall applications of fertilizer if an earlier fall application was not made. Lawns that are not fertilized in September or October will start to go dormant in November.
A late fall application, at this point, made after the grass starts to turn brown, will not be utilized efficiently, and some nutrients will probably pass right through the root zone and become potential pollutants. So, when people call around Thanksgiving and ask about fertilizing, it’s OK if they have made an earlier application. The earlier application should have the lawn nice and green, and ready to photosynthesize.
All fertilization should be completed by the first week of December.
A beautiful green lawn is always nice to see, but realize that the turf will go dormant as the ground turns colder and colder.
Our weather patterns dictate the when factor as you know having had late frost into late November.
While we are all still practicing social distancing due to COVID-19, and all Halifax County buildings remain closed to the public, if you have gardening questions, you can best reach an Extension Master Gardener or Extension staff member by sending an email to email@example.com.
If you can’t email, you can call and leave a message at the Extension Master Gardener Help Desk at 434-830-3383, giving us your name, telephone number and nature of the call. The help desk phone is checked timely and someone will get back to you, although it may be from a different telephone number.
Keep washing your hands, wear your mask, and look forward to a healthier green lawn in the spring if you follow these best management practices.