As summer starts to wind down this month and our mornings are getting cooler, a new challenge for lawn care arises: the emergence of cool-season weeds. These turf invaders, such as Poa annua, henbit, and chickweed, can quickly take over your lawn, leading to a whole slew of problems for you in the coming months.
To prevent these weeds from taking hold, it's crucial to identify them early and apply pre-emergent herbicide in late summer and early fall.
Common Cool-Season Weeds in Georgia
Poa Annua (Annual Bluegrass)
Poa annua, also known as annual bluegrass, is one of the most prevalent cool season weeds here in Georgia. It thrives in cooler temperatures, making its presence most noticeable from late fall through early spring. Poa annua is easily identified by its light green color. Its seedheads are prolific and can quickly spread the weed across your lawn if not controlled.
Henbit
Henbit is part of the mint family and is recognized by its square stems, rounded leaves with scalloped edges, and small, tubular purple flowers. Henbit tends to grow in patches and can rapidly cover bare spots in your lawn, outcompeting your grass for nutrients and space.
Chickweed
Chickweed is a low-growing, cool-season weed that can spread across your lawn in dense mats. It has small, egg-shaped leaves and tiny white flowers that bloom in clusters. Its ability to grow quickly makes it a challenging weed to control once it becomes established.
Prevention with Pre-Emergent Herbicides
Preventing these cool-season weeds from taking over your lawn requires a proactive approach, with pre-emergent herbicides playing a key role.
How They Work
Pre-emergent herbicides are designed to prevent weed seeds from germinating and establishing themselves in your lawn. They form a barrier in the top inch of your soil which blocks annual grass seeds from sprouting.
Timing is Everything
The effectiveness of pre-emergent herbicides depends heavily on timing. The ideal time to apply pre-emergent is in late summer to early fall. This timing coincides with the germination period of these weeds, ensuring that the herbicide is in place before they can begin to grow.
Application Tips
Not all herbicides will treat all types of weeds, so select a pre-emergent herbicide formulated to effectively prevent these specific invaders. Make sure to apply it evenly across your lawn so there are no areas left untreated where weeds can germinate. After application, lightly water your lawn so the herbicide can penetrate the soil but do not over water or disturb the soil too much. Activities like aeration or heavy raking can break the herbicide barrier and reduce its effectiveness.
Maintaining a Weed-Free Lawn
Like with most things, maintaining a healthy, dense lawn should be your first line of defense against any weeds. Regular mowing, proper fertilization, and appropriate watering practices are key to keeping your lawn in top condition. Healthy grass can outcompete weeds for nutrients, water, and sunlight, making it less likely that weeds will take hold. Applying pre-emergent herbicide between late August and mid-September, before the soil temperatures dip below 70 degrees Fahrenheit, is your next line of defense against these specific weeds.
At AgroPro Lawn Care Specialists, we're here to help you achieve a healthy lawn free of unwanted intruders. Contact us today for expert advice on cool season weeds like Poa annua and to schedule weed control treatment specific to your lawncare needs.