Tips For When And How To Apply Weed Killer To Your Lawn
When planning to apply weed killer plan around a predicted rainfall or sprinkler application, and severe hot days or mowing schedule.Weed killers are a contact killer, meaning they absorb the chemical through what comes in contact with the leaf surface and then translocates the chemical throughout the plant. Since weed killers are dependent on contact, it is very important to get good contact with the weed.
Granular weed killers should be applied when grass is damp and should not be watered for 48 hours after application. The dampness of the grass ensures the granular weed killer will “stick” to the leaf. Water applied too soon after application can wash off the weed killer from the surface of the weed before it can be absorbed.
To get good contact with the weed, don’t mow the grass before applying weed killers. Mowing eliminates the weed’s surface area and ultimately decreases the success of the weed killer. Plan to leave your grass uncut for two days after application and five days before.
During drought conditions or if you are having trouble getting adequate control, add spreader sticker which will increase absorption of the weed killer. During stress periods, plants tend to be more defensive and the addition of spreader sticker can be beneficial.
Applying weed killer is a five-step process:
Managing Weeds In Fescue Lawns
Factsheet | HGIC 2309 | Nov 4, 2019 | |
Tall fescue, Festuca arundinacea, is a popular turfgrass grown in the mountains and upper piedmont areas of South Carolina. To keep it looking its best, weeds should be controlled through an integrated approach. This involves knowledge of weed characteristics and the cultural requirements of the turf.
Treating Weeds In New Grass
Depending on the types of fertilizer youve used and the potency of the weeds in your lawn, you may find weeds in a newly seeded lawn fairly quickly. One way to prevent this is to carefully remove all existing grass, weeds and topsoil before applying new topsoil and grass seed. Unfortunately, weed pieces and seeds can easily be left behind in the dirt if you do not thoroughly clear your lawn before applying new seed.
Weeds in new turf may also be the result of low-quality grass seed. Believe it or not, some products may contain seeds for weeds in addition to the grasses they purport to have. Check the package of your grass seed carefully and ensure that it says weed seeds 0 percent before you apply it to your yard. This will give you the best shot at a weed-free lawn.
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What Are The Best Conditions When Applying Weed Killer
Both the season and the changing weather conditions, day-by-day, impact weed killers effectiveness.
Weve already mentioned the importance of changing seasons and the amount of moisture in the soil when using weed killer. The other ideal conditions for applying weed killer are:
- When its unlikely to rain for at least six hours
You dont want the weed killer to become diluted from the rain. This will cause the herbicide to be less effective when its taken up by the plant.
- During calm weather
A gust of wind can blow the spray away from the intended area. A calmer day when you can target the specific area is preferable.
- Mild weather – avoid strong sunshine, frost or freezing temperatures
Weed killers perform better in hot rather than cold weather, but both extremities are difficult.
Hot, dry weather encourages weed hardiness and growth, which reduces the movement of herbicide into and throughout the plant. If youre using herbicide-based weed killers, the hot weather will make it less effective, which is why you should target weeds in Spring or Fall.
And cold weather also isnt practical. Plants break down herbicides using their metabolism. But plant metabolism slows down in cold conditions. This then extends the amount of time it takes for the plant to react to the herbicide and be killed.
How To Control Weeds In A Newly Seeded Lawn
However, you can get rid of these weeds just as fast as they have appeared.The important thing to remember when new weeds appear in your newly sown lawn is not to act hastily do not apply a Feed, Weed and Moss Killer type product of any kind on a newly sown lawn.
Although this can be frustrating and we can appreciate that a quick solution will be desired, the good news about these types of weeds is that they are largely shallow rooting and should come out with the first mow at the 6-8 week mark after sowing. If they dont, they should be easy to pull out of the turf.
If you find that the weeds are recurring past the 6-8-week mark, you may wish to consider using a selective herbicide to spot spray your weeds. Some weed killers such as glyphosate kill more than just weeds, so it is important to not apply these as if they are not done precisely, they can kill your grass. Shop bought selective weed killers will recommend when to apply their product and how often and you should read the instructions thoroughly and adhere to them.
In short, here’s what you should do if you encounter weeds in your newly seeded lawn:
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Safety Rules When Using A Weed Killer
Can a weed killer harm a person? The instructions for herbicides always indicate the level of danger and toxicity to humans. All substances that are part of the selected product have various degrees of toxicity.
Mostly, the herbicides are medium-toxic to humans. But they can be very bad for little kids and pets, especially liquid products. Thats why, herbicide treatments must be applied only when you wear protective clothes, rubber gloves, respirators, and goggles.
Important advice: when using a weed killer, protect mucous membranes and exposed skin from any contact with the grass killer.
What are the effects of weed killer on skin? Rash and redness is possible. Wash with water if you have a herbicide on skin.
If the herbicide enters the mucous membranes, the digestive tract should be washed with plenty of water vomit and then consult a doctor.
After the application of a weed killer, the sprayer is thoroughly washed with a solution of detergent until the full removal of the products residue.
Controlling Lawn Weeds With A Pre
Pre-emergent weed killers control annual lawn weeds while they sprout, which means the herbicide must be on the lawn before the seeds begin to germinate. Annual plants grow during one season, and then set seed and die. Summer annual weeds like crabgrass and goosegrass germinate in the spring and winter. Annual weeds like common chickweed and henbit sprout in early fall. Consequently, to control summer annual weeds, apply a pre-emergent weed killer in early spring, and to control winter annual weeds, apply a pre-emergent herbicide in early fall. If you can already see annual weeds in your lawn, it’s too late to apply a pre-emergent herbicide.
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Follow The Instructions To Treat Weeds
Not all weed treatments are created equal. Make sure that you thoroughly read and understand the instructions that your weed killer comes with. Some chemicals could prove to be hazardous to your lawn or your pets. Some killers can be used multiple times on the same patch of land with no negative side-effects, while others are strictly one-use only.
Whole Lawn Or Spot Treatment
- If the weeds are sparse or limited to certain areas of the lawn it is not necessary to spray the whole lawn you can spot spray the weeds or only spray the affected areas.
- Coarse grasses can also be a weed in fine turf lawns. The broadleaf weed killers will have little effect on these and spot treatment with Weed Weapon Invade Gel is the best option. Apply the gel to the central growing crowns of the coarse grass.
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Conditions For Using Lawn Weed Killer
- Ensure you have fertilised the lawn beforehand to maximise the effect of the weed killer
- When moisture is available in the soil. You can harm the grass in drought conditions
- When it is unlikely to rain for at least 6 hours
- On dry grass. Wet grass will dilute your weedkiller
- In calm weather wind will blow spray even from a watering can sprinkle bar
- Avoid frost or freezing conditions which may occur in spring
- Avoid strong sunshine
- In summer it is best to apply weed killer in the cooler evenings
- Any time after fertilising. Let the feed kick in then treat the weeds to get a better weed kill
- After mowing. Leave at least 2 days if applying liquid lawn weed killer to the whole lawn. Dont mow for a further 3 days
- When mowing prior to weed treatment dont mow close. If you mow close and chop the leaves off the weeds there is nothing left to spray!
Guidelines For Using Postemergence Herbicides
When choosing an herbicide, make sure that it will control the weed and that it is recommended for your turf. Before using, read the entire label and follow it precisely for rate and timing. The following tips will help you achieve optimum control.
- Most broadleaf weeds are best treated in the spring or fall when air temperatures are between 65 and 85 degrees F. During hotter temperatures, turf damage is more likely to occur.
- At the time of treatment, soil moisture should be adequate. When stressed by drought, weed control is poor and turf damage may occur.
- Do not mow immediately prior to or after application. Mowing lessens the amount of surface area that the herbicide contacts.
- With spray applications, treat weeds when no rain is expected for at least 24 hours.
- Avoid treating on windy days because herbicide spray drift can injure ornamental plants.
- Best results occur when weeds are young.
- For acceptable control, repeat applications, 10 to 14 days apart, may be required.
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When Can I Use Weed Control Products On My New Grass
All weed control products are different, but in general, it is recommended to wait until the new grass has been mowed at least 4 times before using a crabgrass preventer or other weed control product. Always refer to the product label for specific information related to the weed control product you are using. If you want to prevent crabgrass from invading while growing new grass, we recommend using Scotts® Turf Builder® Triple Action Built for Seeding. The ingredients in this product prevent crabgrass when seeding and boost root development of new grass plants.
When You Should Spray Your Weeds
The best time to treat weeds is when they are actively growing. This means you should start spraying and treating in the spring, usually sometime in April. Youll have to maintain your weed-killing regiment into late September/early October.
Its best not to jump the gun when using weed killers. Theres a lot of weeds in early spring that wont surface until later on in the year. Most weed killers are contact sprays: The treatment will only be effective if they make direct contact with the weeds. Youre better off waiting until May: By that time most of the weeds will have emerged, making them much easier to dispose of.
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Will Heavy Rain Wash Away Pre
One of the positives of pre-emergent is that it resists breakdown by water quite well. Pre-emergents are designed to bond with the soil and remain for up to 8 weeks.
That said, all herbicides are soluble if inundated with enough water. The chances of your pre-emergent herbicide being washed away by heavy rain increase if the ground it is applied to is sloped or if there is very little grass and/or other vegetation to hold the soil in place.
While heavy rain will somewhat reduce the effectiveness of pre-emergent herbicide, it is generally resistant to natural precipitation patterns. You may see a small drop off in effectiveness if rainfall is heavy, but it takes a lot to wash away pre-emergent herbicide.
Can You Apply Pre-Emergent to Wet Grass?
It is not recommended to apply pre-emergent herbicides to wet grass. Doing so may cause the herbicide to stick to grass blades rather than reach the soil.
For maximum effectiveness, apply pre-emergent to dry grass shortly before rain or planned watering. Watering after application will help draw the pre-emergent down into the soil, where it must be to function.
What Is The Best Time Of Day To Apply Weed Killer
The best time of day to apply a weed killer treatment is in the late morning or early afternoon. It helps prevent rapid evaporation before the weed killer can actively absorb into the dirt and start to kill the weeds.
A late afternoon treatment can also be effective, as long as it is not too hot or too cold.
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Top Recommended Professional Lawn Care Company: Trugreen
The This Old House Reviews Teams top selection for lawn care, TruGreen, offers both pre- and post-emergent weed control to restore your lawn to its former health and make sure it can compete against future weeds. The lawn care company offers five annual plans with varying levels of coverage in every state except for Alaska. If youd like a free quote, call 866-817-2287 or fill out this simple form.
The Weed Control Timing Chart
Herbicides may be almost completely ineffective if applied at the wrong time of year. There is an optimum time frame to apply an herbicide to each weed. In most cases, this time is early in the weeds life cycle, but in some cases, herbicides should be applied during a different growth stage. Generally, weeds should be actively growing when an herbicide is applied. In certain instances, only a pre-emergent herbicide may provide effective control. Remembering when to apply herbicides for the many different weeds can be a challenge. The herbicide label provides definitive information concerning the turf growth stage, time of day, and weather conditions when the product may be applied, but this simple chart can help in making a plan for the timing of lawn weed control.
The Lawn Weed Control Timing Chart was developed to help remove confusion and guesswork when determining the recommended time of year to control various weeds in lawns. The chart is arranged with a list of common weeds in rows on the left, and months of the year in columns on the top of the chart. The row for each weed listed has a colored bar in the row, indicating the time frame when the weed may be most effectively controlled. Green bars indicate application time ranges for post-emergent herbicides , and goldenrod bars indicate application time ranges for pre-emergent herbicides.
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What You Might Need
What you will need is a selective herbicide that targets broadleaf weeds like dandelions. A non-selective herbicide like Round Up will target everything including healthy grass, shrubs and bushes.
So, youâll want to avoid that unless you want to start over. Wait several weeks after treating an area with both types of herbicides before you can plant new grass seed because the herbicide will prevent new seed from germinating.
Even selective herbicides such as 2,4 D can do damage to shrubs and bushes, so be careful where you spray it.
There are two types of weed control: One is granular, and the other is liquid. The granular type is what you would likely get at Home Depot, Loweâs and other stores if youâre going to do it yourself. Scott’s Turf Builder weed and feed is an example of granular.
The liquid type is what you would likely buy to spot treat weeds. Ortho Weed B-Gon is a liquid spray that doesn’t contain fertilizer.
Lawn care companies may use either kind. If theyâre treating an entire lawn with liquid, it will probably contain a fertilizer to give your lawn a shot of nitrogen.
This time of year, grass is already green and growing like crazy. A fertilizer will help boost color and growth, and it’s also definitely good for helping a new lawn get established.
Avoid weed control on a new lawn until it is established.
As for the application, itâs always best to follow the instructions on the bag or bottle.
Caring For Your New Lawn After Germination
As your new lawn becomes established, you can start easing up on the water, depending on the weather. If you continue your everyday watering routine, youre likely to overdo it and rot the young seedlings. Also, if the ground is too wet, you can inhibit root growth.
When you have a pretty even ground cover of new seedlings, try skipping a day of watering and see what happens. Watch the grass carefully. If the color starts to go from bright green to dull gray green, the grass needs water. You may have to water some quick-to-dry areas with a handheld hose.
If the grass doesnt dry out, keep stretching the intervals between watering until youre on a schedule of once or twice a week, or as needed. When you do water, dont forget to water deeply, getting the moisture down 6 to 8 inches.
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