While it may be hard to believe most weeds blow into your lawn as seeds and sprout the minute they find enough bare soil moisture, and light to grow. This is true for both annual and perennial weeds. Annual weeds sprout, grow, flower, seed and die within one year. Perennial weeds sprout from seed as well, but the weed plant continues to grow and spread for more than one season (even though the top may die back in the winter).
Weeds enter a lawn for one reason: your lawn is not growing well. In fact, two of the most common reasons for weeds in a Bermuda grass lawn are drought and shade. It is not that drought and shade increase the number of weeds or weed seeds trying to creep into your turn. Instead drought and shade cause Bermuda grass to thin, thus offering weed seeds an open space to germinate and grow. Your trouble may be different. Compacted soil, cold damage, insect/disease damage, flooding, steep slopes (causing dry soil), lack of fertilizer, and irregular pH can cause Bermuda grass to thin. The underlying point is that a thick, well grown stand of Bermuda grass is the first step toward "closing the door" and stopping weeds. Even then, most of us will have to employ various weed control measures to keep our lawns weed free.
TIP: Neighboring lawns, woods and adjacent untended areas product enormous numbers of weed seeds that blow into your lawn. If possible, mow or "weed-eat" them to prevent seed formation.
Types of weed control for Bermuda Grass
There are two ways to control weeds in a lawn: as the weed seeds germinate and after the weeds have already germinated. When using weed control products, always make sure the product is approved for use on Bermuda grass and follow the labeled directions. Do not apply more than the recommended rate; it will not give you better results and may injure your lawn.
PRE-EMERGENCE WEED CONTROLS: kill immature weeds immediately after they germinate and before they emerge from the soil surface. Since annual weeds like annual bluegrass and henbit die and return from seed each year, a pre emergence wed control will eradicate them from your Bermuda grass lawn over several seasons. At the same time it will prevent annual and perennial weed seeds that blow into your lawn from emerging. Most pre emergence products are sold in a granular from with or without fertilizer that you spread using a fertilizer spreader. If is important to spread the chemical wall to w all at the recommended rate. Areas that are not covered by the chemical will not be protected. After spreading the product, irrigate your lawn with at least .5 inches of water to activate the chemical (unless otherwise stated on the bag). Once activated, pre emergence weed controls create a chemical barrier in the upper inches of your lawn that will prevent weed seeds from germinating. Do not cultivate, aerate, or disturb the soil after treating your lawn or you will disrupt the chemical barrier and open the soil to weed infiltration. Pre emergence weed controls are usually effective for 2-3 months, depending on the temperature and amount of rainfall.
POST-EMERGENCE WEED CONTROLS: kill weeds that are already growing in your lawn. These products are referred to as "selective" since they are targeted at specific annual and perennial weeds listed on the label. Usually, controls will either treat grassy weeds like crabgrass or broadleaf weeds like chickweed. Choose the weed control spray that best suits your needs. You may need to purchase a spray for each category of weeds. In most cases, post emergence products are designed to disrupt one of the weed's critical metabolic processes and should be sprayed when the weed is actively growing. If the weed is dormant because of cold weather or drought it may not die. Post emergence products are most often sol in liquid spray. The liquid sprays are very effective when weeds are young and actively growing. Spray on a day when your air temperatures are 60 to 80 degrees and the grass is dry. Avoid spraying during the 4-6 weeks in the spring when your Bermuda grass is greening up. Post emergence weed controls are sometimes sold in granular form that is spread with a fertilizer spreader when the grass is wet. The dry particles need the moist to adhere to the weed leaves.
Another group of post emergence weed controls are the non selective sprays such as Round-Up. The term non-selective means they will kill all vegetation including Bermuda grass. The trick is that non selective weed sprays are absorbed through plant leaves. During the winter months when your Bermuda grass is brown, you can carefully spray green weed without affecting dormant Bermuda grass. WATCH OUT! Be very cautious and make sure that your lawn's leaves and stolons have not emerged during a winter warm spell. Even then, spray only the weed and expect some Bermuda grass in the vicinity to be killed as well.
When to apply Weed Controls on Bermuda Grass
When it comes to weed control, timing is critical. Pre emergence weed controls have to be applied before weed seeds germinate or they are useless. Post emergent weed control sprays and granules have to be applied when the weeds are young, tender and actively growing. It is better to be a little early than a little late.
Under normal conditions, a thick, lush Bermuda grass lawn will remain weed free with two application of granular pre emergence weed control (late winter and early fall) and spot treatments of problem weeds with a post emergence weed control spray in mid winter and early summer. Here are two options when trying to renovate a very weedy lawn or if you live near a major source of weeds like an old pasture.
LATE WINTER: Apply a pre emergence weed control when the soil temperature reaches a consistent 50 degrees. This is usually February or early March, when the Forsythia is in bloom. This application will control annual weeds and perennial weeds that germinate in the spring. Make sure the product is approved for use on Bermuda grass and apply at the recommended rate. Do not aerate (core) for 3 months after you apply pre emergence weed control because it will affect the chemical barrier. Irrigate after applying useless otherwise state on the bag. Do not use a pre emergence weed control that contains fertilizer. If you fertilize now, you might stimulate your law to break dormancy during a warm spell, only to be damaged by freezing temperatures.
LATE SPRING AND SUMMER: Apply pre emergence weed control without fertilizer around June 1 to control annual and perennial weeds that continue to germinate into the summer. If your lawn is mostly weed free and weeds do not usually blow in from surround areas, you can skip this application. Use a product approved for use on Bermuda grass and apply at the rate recommended on the bag. Remember not to aerate for 3 months after you apply pre emergence weed control because it may affect the chemical barrier. Irrigate after applying unless otherwise stated on the bag.
Once our Bermuda grass lawn is completely green and soil temperatures reach 75 - 80 degrees begin treating weed outbreaks with a post emergence weed control spray approved for use on Bermuda grass. Do not spray weed control during March/April when your Bermuda grass is turning green since it can harm your lawn. Most sprays should be used when the air temperature is 60-80 degrees (check the product label) and weeds are young and tender. If you wait another month or two, weeds will be older tougher and require repeated applications to kill them.
If your lawn is still overrun with weeds in mid-summer, consider using a combination fertilizer/post emergence weed control (granular) when you fertilizer around July 1. Follow the labeled instructions and make sure your lawn is wet when you broadcast the product.
EARLY FALL: Wait until soil temperatures drop to 70 degrees to apply pre-emergence weed control (without fertilizer) to your Bermuda grass lawn. This is usually around September 15 in the upper South and October 15 in the lower South. If you think you will forget, you can apply pre-emergence weed control when you fertilize in early September but you will be sacrificing some effectiveness. This application will control weeds like annual bluegrass and henbit to germinate in the fall and winter.
Either way, make sure the pre emergence product is approved for the Bermuda grass and apply at the rate recommended on the bag. Irrigate after apply in unless otherwise stated on the bag. This application will last 2-3 months.
WINTER: Apply a pre emergence weed control without fertilizer 2 - 3 months after your fall application (optional application). This is usually in late November/early December. If your lawn is mostly weed free and weeds do not usually blow in from surrounding areas, you can skip this application. Use a product approved for use on Bermuda grass and apply at the rate recommended on the bag. Remember not to aerate (core) for 3 months after you apply pre emergence weed control because it may affect the chemical barrier. Irrigate after applying unless otherwise stated on the bag.
During the winter, treat winter weed outbreaks as soon as you see them (young weeds will die quickly) with a post emergence weed control spray approved for use on Bermuda grass. This is usually in January and February. Most of your problems this time of year will be from annual weeds like annual bluegrass and henbit. Spray on a warm afternoon (approx 60 degrees) when the weeds are young and actively growing. It may take two applications to kill them. You can also spray during the winter with a non selective weed control like Round-Up. Make sure your Bermuda grass is completely brown and spray only the leaves of the weeds. Be very careful because Bermuda grass stolons and leaves can emerge prematurely during a winter warm spell. With both types of sprays, read the product label for specific instructions.
