Healthy and lush St. Augustine grass on your lawn indicates an optimum environment for the growth of weeds. Healthy grass means your lawn has perfect soil conditioning and enough nutrients for growth, which weeds compete with your grass to obtain. Specific weeds are most likely to be found in your St. Augustine turf. Luckily, efficient control methods destroy these weeds and improve grass growth.
Firstly, identifying common weeds is the initial step towards planning how to eliminate them from your lawn. It is an intricate process that guides you towards choosing which herbicide works best without damaging your grass.
Common Weeds in St. Augustine Grass
There’s a long list of weeds that attack lawn grass. However, some pesky weeds are more inclined towards St. Augustine grass despite its resilient nature. These weeds belong to two categories: Broadleaf (with thicker leaves) and grassy weeds (which resemble your St. Augustine grass).
Broadleaf weeds to look out for include:
Chickweed
Chickweed is also known as starwort or satin flower. Chickweed does not grow more than two inches and produces small white flowers. It is an annual winter weed, with its seeds sprouting in the fall season. Therefore, apply pre-emergent herbicides in the fall or spring seasons.
To ensure chickweed seeds do not survive in your lawn, apply Scotts Turf Builder Southern Triple Action. This herbicide, whose active ingredients are Atrazine (1.352%) and Bifethrin (0.139%) is perfect for warm season grasses like St. Augustine. Spray the whole lawn without worrying about damage to your grass.
Upon application, this herbicide performs three functions:
- Killing weeds
- Feeding your lawn
- Getting rid of pests e.g. fire ants
You feed your lawn, allowing it to grow more robust, and withstand stresses such as heat and drought even as you eliminate chickweed. After application, water it in by irrigating. Irrigation helps the herbicide to seep in and reach the soil surface.
Dollar Weed
Dollar weed thrives in wet conditions. It is a dark green perennial warm season weed that you can identify through its lily pad-like leaves, also known as silver-dollar shaped leaves. In St. Augustine grass, the dollar weed indicates overwatering or excessive moisture in the turf grass. Stems of the dollar weed form roots wherever the nodes touch the soil, thus its fast growth.
The best herbicide to eliminate dollar weed is Metsulfuron Methyl Herbicide, whose active ingredient is Metsulfuron.Treat your lawn every eight weeks, or even better, once a month for best results. However, do not water in the herbicide after application. Consistent and timely application defeats the roots below the ground and the stems, eliminating chances of repopulation of dollar weed.
Precaution: Do not apply Metsulfuron Methyl Herbicide near ornamental plants, trees, or shrubs less than two years old. This herbicide might not harm your mature St. Augustine grass, but it is unsuitable for use on turf less than a year old.
White Clover
To identify this weed, watch out for:
- Pink centered flowers
- White crescent-shaped petals
While people love the white clover in planted flower boxes, it becomes uncontrollable when it gets on your lawn. It is a re-seeding winter annual weed, requiring fast elimination by applying herbicides like Ortho WeedClear Weed Killer. This herbicide kills broadleaf weeds from the root, thus eliminating white clover effectively.
Precaution: Do not use this herbicide on Floratam (a St, Augustine grass variety) because it is susceptible and you will damage it upon application. It is also vital to note that Ortho WeedClear contains 2,4-D, an active ingredient that often disagrees with St. Augustine grass. Read the mixing rates carefully, apply at temperatures less than 90°F, and spot treat, to reduce the negative impact on your turf.
Grassy weeds in St. Augustine grass are:
Annual Bluegrass (Poa Annua)
Grassy weeds like Poa Annua require up-close identification because their leaves resemble grass blades. Annual bluegrass is an annual weed that:
- Is bright green (appears brighter than St. Augustine grass)
- Has smooth leaves with a pointed tip
- Produces a white feathery, tufted seed head that is unsightly. The seed head is easily identifiable in spring. However, you can also spot it in summer and winter.
Prevent growth of Poa Annuaby carrying out pre-emergent control measures. However, it won’t be hopeless to apply Spectracide Weed Stop for Lawnsupon identification of annual bluegrass. This herbicide is ready to spray and should be applied any time temperatures are below 90°F. A great advantage is that it kills weeds already emerged and weed seeds in the ground.
Since this herbicide contains active ingredients like dicamba dimethylamine salt, it does not harm St. Augustine grass. Conclusively, you can blanket spray your lawn.
Crabgrass
Luckily, crabgrass is easier to identify than most grassy weeds. It is an annual weed, conspicuous, and proliferates. Further identification is done by looking out for:
- Coarse textured yellowish-green grass
- Spreading stems with numerous branches
- Roots developing at nodes on the prostrate stems
For efficient treatment of your lawn against crabgrass, use Hi-Yield Atrazine Weed Killer. It has Atrazine (4%) as an active ingredient, safe for use on your entire lawn. The herbicide controls both emerged weeds and weeds from seed, saving you weed emergence issues in future.
Pre-emergent control measures are encouraged, but post-emergent weed control measures through safe herbicides also goes a long way in eliminating crabgrass.
Pro Tip: Read the instruction label attached to all herbicides to prevent any misuse of products. Ensure you read everything in detail to ascertain the suitability of herbicide to St. Augustine grass.
Cultural Methods of Weed Control in St. Augustine Grass Lawns
As long as your lawn is well maintained, through mowing, fertilizing and irrigation, weeds will be the last of your worries. Healthy and lush St. Augustine grass is thick and does not permit growth of weeds. As long as your turf grass is healthy, weeds find it challenging to compete for space and nutrients.
Cultural weed control methods include:
- Mowing
Mowing involves proper and timely grooming of your lawn. It reduces the chances for weeds to spread seeds. Through mowing, you also scout the area, observing for emergent weeds. Bag up the grass clippings to eliminate any seed heads that might spread seeds right back to your lawn.
- Fertilizing
Maintaining a regular schedule for fertilizing your lawn is mandatory. Although fertilizers might provide nutrients and optimum conditions for the growth of weeds, they significantly promote healthier growth of your St. Augustine turf grass. The thicker your turf is, the harder it is for weeds to survive. Apply fertilizer regularly, throughout the growing season, for the growth of healthy and aggressive grass.
- Irrigating
Watering your lawn is vital in promoting healthy grass growth. If you fertilize and forget to irrigate, you leave your lawn at a disadvantage because grass won’t grow well. Irrigating also discourages the prevalence of pests, which hinder thickening of your St. Augustine grass. As long as you water your grass adequately, it will flourish and stand a better chance at beating weed growth.
- Hand Pulling
Pulling out weeds by hand can only work if there are few weeds on your lawn. Pluck weeds from the root to prevent re-emergence. Working by hand allows you to observe what is growing in your lawn. Therefore, it gets easier to identify broadleaf and grassy weeds.
Cultural methods of eliminating weeds also act as preventative measures for re-emergence. If you prefer the organic route, apply organic productsformulated at home or bought ready-made.
Can St. Augustine grass choke out weeds?
St. Augustine turf grass is aggressive and competitive. These features allow it to compete with several weeds. As long as you have employed proper maintenance practices e.g. frequent mowing and proper fertilization, your turf will choke out any weeds that find their way on your lawn.
The thicker and healthier your St. Augustine grass is, the more difficult it is for weed penetration. It has stolons that develop above the ground and root in the soil, promoting faster growth. Therefore, as long as your turf grass establishes itself in the soil, weeds won’t grow as easily.
Weeds attack grass that is:
- Weak or unhealthy
- Scalping
- Dead
- Patchy and brown
While many lawns with St. Augustine grass might choke out lightly weeded sections, herbicide application is required to eliminate weeds and their seeds.
References
- Gary Forester, Horticulture Extension Agent, Horry County Extension Service, Clemson University:St. Augustine Grass Yearly Maintenance Program
- UMassExtension Turf Program, Center for Agriculture, Food,andtheEnvironment, University of Massachusetts Amherst: Biology and Management of Crabgrass
- David R. Chalmers, et al, Texas A&M AgriLife Extension: Maintaining St. Augustine Grass Lawns
- Chris Marble, et al, IFAS Extension, University of Florida:Effects of Metsulfuron-Methyl-Containing Herbicides on Ornamentals
MORE FROM LAWN CARE PROS:
- How to Make Bermuda Grass Thicker and Greener
- How to Revive St. Augustine Grass and Get it to Grow Back
- Best Crabgrass Killer that Won’t Kill Grass [Top 8 + Reviews]
- When to Apply Grub Control: Best Timing to Put Down Grub Killer
FAQs
How do you kill weeds in St Augustine? ›
Mix one tablespoon of dish soap with one gallon of white vinegar and a cup of salt. Place this mixture in a spray bottle or use the spray mode of a garden hose. Spray the weeds in your grass with this mixture during the warmest and brightest part of the day.
Will vinegar kill St. Augustine grass? ›Can vinegar kill weeds? Yes, it most certainly can. But there's a little bit more to it than just taking a bottle of vinegar from your kitchen and using that in the garden.
Can you spray MSMA on St Augustine? ›St. Augustine, as well as centipede grass, are sensitive to certain chemicals found in popular herbicides such as 2,4-D, dicamba, MCPP and MSMA. These active ingredients will actually damage your St. Augustine grass lawn.
Will roundup for lawns kill St. Augustine grass? ›You can kill off the weed and St. Augustine grass in the worst patches with glyphosate (Killzall, Roundup and other brands).
How do you keep weeds from growing in St. Augustine grass? ›A pre-emergence herbicide can be applied to thin lawns to protect them from weeds until they thicken and cover. Mow St. Augustine grass at your lawnmower's highest blade setting to select against bermuda.
What kills the weeds but not the grass? ›Pre-emergent herbicide is a great way to stop weeds without harming your grass. Once it's spread, pre-emergent herbicide enters the soil and remains there for weeks or months. As long as the pre-emergent is in the soil it kills weed seeds as they sprout.
What kills weeds but not St. Augustine grass? ›The easy grip control is perfect for broadcast applications so you can kill over 250+ weeds without damaging your lawn. * Use Ortho® No. 1 weed killer for St. Augustinegrass lawns, including Floratam.
Is vinegar better than roundup? ›When equal amounts were given orally and compared, it took less acetic acid to kill rats in the laboratory test that it did glyphosate. The acetic acid in even household vinegar was MORE toxic than Roundup!
Is baking soda good for St. Augustine grass? ›Yes, baking soda will kill St. Augustine grass.
Can you spray 2,4-D on St. Augustine? ›St. Augustinegrass is sensitive to 2,4-D, so follow label directions for mixing and use. Do not apply herbicides unless grass and weeds are actively growing and are not suffering from drought or heat stress; therefore, water the lawn thoroughly the day before application.
What herbicide kills crabgrass in St. Augustine? ›
When it is actively growing, hand pull if you can or use a non-selective herbicide such as glyphosate or glufosinate as a spot treatment. Remember that these products will also kill St. Augustinegrass so they should be used sparingly. Crabgrass growing in turf.
What kills crabgrass but not St. Augustine grass? ›The best way to kill actively growing crabgrass in your lawn is to apply a selective post-emergent crabgrass killer that contains Quinclorac. It will remove the weed without killing lawn grasses like Bermuda, Zoysia, Fescue, (Don't use on St. Augustine, Floratam).
Will Dawn dish soap kill St. Augustine grass? ›Dish Soap Will Harm Your Grass
The degreasing agents and bleach that is often found in dish soaps are toxic to plants and is designed to destroy the fatty acids and organic matter that is commonly found in food. It will also destroy and break down your paint's wax and clear coat.
Epsom salt is an organic compound that is full of beneficial minerals for lawns. Iron in Epsom salt, for example, helps grasses to grow healthy and strong. Meanwhile, the magnesium in Epsom salt balances the PH level in your grasses so that it doesn't become too acidic.
How do you identify weeds in St. Augustine grass? ›- Examine the grass stems. St. ...
- Look at the leaves. Broadleaf weeds are easily distinguished from grass leaves. ...
- Use the soil condition to help identify the most likely weeds. Annual and perennial grasses grow in St.
The best fertilizer for St Augustine grass is any fertilizer that has one pound of nitrogen for every 1,000 square feet of sod. Fertilizing every two months is ideal unless you apply slow release fertilizer that can be spread every 10 weeks.
What causes weeds in St. Augustine grass? ›If allowed to, St. Augustine grass could overtake and kill most shrubs in your yard. Most weeds appear because of improper cultural practices such as mowing too closely or infrequently, improper fertilization or irrigation. These are the primary causes for thin or weak turf.
Will St. Augustine grass choke out weeds? ›St. Augustine will not grow as quickly as Bermuda but can grow such a large mat of grass that it will potentially choke out all weeds in your lawn. Growing blades to a higher level but mowing often will cause the grass to thicken.
What kills weeds permanently? ›Yes, vinegar does kill weeds permanently and is a viable alternative to synthetic chemicals. Distilled, white, and malt vinegar all work well to stop weed growth. Will table salt kill weeds? Yes, table salt will kill weeds.
How do I clear my yard full of weeds? ›- Lawn Aeration. Compacted soil is the enemy of a great lawn. ...
- Pull weeds out by hand. Perhaps the most environmentally-friendly way of getting rid of weeds is to pull them out by hand. ...
- Use a home-made herbicide. ...
- Sprinkle cornmeal. ...
- Cover with mulch. ...
- Pickle them with vinegar.
What grass will choke out weeds? ›
Zoysia is an extremely aggressive spreading grass that can literally choke out weeds.
How do you get rid of creeping Charlie in St. Augustine grass? ›Make sure to remove the plants you've pulled so they can't re-root. A dethatching tool, also called a power rake or vertical mower, can be used to clean up larger areas of creeping Charlie-infested lawn. This tool makes small cuts in the soil and the roots so you can “comb out” the creeping Charlie with a rake.
Can I spray Roundup on dormant St. Augustine? ›They wrongly assume that because the warm-season lawn grass is dormant that the herbicide won't hurt it. Unfortunately, turfgrasses like Bermuda, Zoysia and St. Augustine don't typically go completely dormant in the winter. That means they can still be damaged by herbicides in the “off season”.
Can I just pour vinegar on weeds? ›Yes, it's true… vinegar does kill weeds, especially when used along with dish soap. Dish soap, vinegar and a spray bottle are all you need for making your own weed killer. The acetic acid in vinegar “sucks out the water” from the weed, which dries it up.
Will grass grow back after vinegar? ›Will Grass Grow Back After Vinegar? Yes, unless the grass seedlings are under two weeks old. In that case, the roots are not developed enough to grow new blades. Broadleaf grasses are more likely to die back to the soil, but the roots will grow new leaf blades anyway.
What mixed with vinegar kills weeds? ›According to Reutinger, the weed kill recipe calls for mixing together: 1 cup of salt. 1 tablespoon of dish soap. 1 gallon of vinegar.
Are coffee grounds good for St. Augustine? ›Coffee grounds seem to add to the soil helping to create sort of a compost. We had a spot in our yard that had coffee grounds added to it almost everyday for many years. Around it and on top of the pile it grew the best St. Augustine grass you ever saw and had many earthworms in it as well.
Are coffee grounds good for St. Augustine grass? ›These things are great for nutrient poor lawns and lawns on clay or sandy soil. However, coffee grounds still contain some residual caffeine, which can cause harm to the micro fauna in your soil, and that's why it is not recommended to apply coffee waste directly to your lawn.
Can you put too much nitrogen on St. Augustine grass? ›Excessive Fertilizer
Too much fertilizer can burn your lawn, especially if it's very high in nitrogen. Fertilizer burn happens when too much nitrogen is used and scorches the leaves—signs include yellow and brown discoloration and root damage.
Set the mowing height at 21/2 to 3 inches (3 to 31/2 inches in shady lawns). The lower the mowing height, the more frequently you will need to mow. Frequent mowing at a lower height produces higher quality turfgrass.
How often should you cut St. Augustine grass? ›
St. Augustine grass should be mowed once a week during the growing season, which is typically from April through October in Florida. In general, St. Augustine mowing heights during the summer are about 2–4 inches.
What kills weeds and crabgrass but not grass? ›Actively growing crabgrass in your lawn calls for selective, post-emergent herbicides, such as Image All-In-One Lawn Weed Killer or Image Herbicide Kills Crabgrass, that kill crabgrass and leave your lawn grass untouched.
What is the number one crabgrass killer? ›| Best Crabgrass Killer | Shelf Life | Active Ingredients |
|---|---|---|
| The Andersons Barricade Weed Control | --- | Prodiamine 0.48% |
| BASF Drive XLR8 Crabgrass Herbicide | 45 Days | Quinclorac 18.92% |
| Roundup Crabgrass Destroyer1 - Tough Weed Killer | --- | Topramezone 0.0092% |
| BIOADVANCrabgrass Weed Killer | 5 Years | Fenoxaprop-p-ethyl 0.41% |
Answer: Yes the Scotts Halts Crabgrass & Grassy Weed Preventer is a pre emergent that is safe on most all lawn types including St Augustine grass, and only excludes use on dichondra and bentgrass lawns.
What does crabgrass look like in St. Augustine grass? ›How to Treat and get Rid of Crabgrass in your St.Augustine Lawn!!! (A Do ...
Can I use Scotts triple action on St. Augustine grass? ›Scotts® Turf Builder® Southern Triple Action is made specifically for these Southern lawn types: St. Augustine (including Floratam), Carpetgrass, Centipedegrass, and Zoysiagrass. This product is cannot be applied to Bermudagrass. Apply with a Scotts® spreader when weeds are actively growing.
Will St. Augustine crowd out crabgrass? ›Crabgrass only lives for a year. However, the coarse weed can be an unpleasant sight when it leaves its seeds in the ground. These seeds will keep germinating and crowding out your lush St. Augustine lawn every year.
Can I spray soapy water on my grass? ›Dish soap isn't selective about removing oils and drying out cell membranes. It will dehydrate and kill the grass just as it would the nasty pests in your garden. So, yes, dish soap is not an entirely safe way to remove insects and lawn pests.
What does baby shampoo do for your lawn? ›After application of baby shampoo to your lawn or garden soil will accept water more readily and uniformly overall. It will allow water to soak in deeper which enhances deeper roots. It also helps deter pests as they do not like the taste of the soap.
Does vinegar Epsom salt and Dawn kill grass? ›Mixing vinegar with Epsom salts and Dawn liquid dish soap can make a safe, effective weed killer. The more concentrated the vinegar is, the more effective it will be at killing weeds. If the vinegar is too diluted or if you use your vinegar solution in inclement weather, you won't get good results.
What does Dawn dish soap do for your lawn? ›
Concentrated dishwashing liquid breaks down the healthy, oil-based tissue in the plant. This leads to leaves that can no longer retain moisture. Combined with a little heat and sunlight, that means you could end up with patches of crispy, brown grass in as little as a single day.
How can I make my St. Augustine grass healthy? ›St. Augustine grass performs best if fertilized regularly, on a schedule. Fertilize it initially in spring after it has finished greening up. During the summer, maintain a fertilizing schedule such that you feed it every 6 to 8 weeks.
What is the best time to water St. Augustine grass? ›A: The best time is in the early morning hours (1:00am to 3:00am), prior to the dew. Watering in the late morning may be detrimental if it extends the time the lawn is naturally wet from dew, which may accelerate disease issues. Watering during the day wastes water due to excessive evaporation from the sun.
How do I identify the weeds in my lawn? ›Weed Identification - Identify 21 Common Weeds in Lawn - YouTube
How do you get weeds out of St Augustine? ›Manually digging them out, using a vinegar solution, or applying herbicides are effective methods to kill weeds in St. Augustine grass.
› kill-weeds-in-st-augustine-... ›What To Use To Kill Weeds In St Augustine Grass 2022
St Augustine Grass Weed Control
Southern Ag's Atrazine Weed Killer is one of the most common herbicides for St Augustine grass. Featuring Atrazine as the active ingredient, Southern Ag's product is safe for St Augustine turf. It is also an efficient killer of weeds.
How do you kill weeds but not grass in Florida? ›A layer of mulch 2-4 inches deep should be sufficient to keep weeds at bay. Use Herbicides! If weeds seem to be getting the better of you, herbicides might be the way to go. Be sure to select a pre-emergent herbicide that will kill the weeds you don't want, but will leave your existing plants unharmed.
What kills Dollarweed but not St. Augustine grass? ›And with St Augustine grass the safest most effective herbicide is Metsulfuron Methyl – it is expensive, it is slow, it is difficult to apply but it is an effective herbicide on dollar weed and safe to use on St Augustine grass. When shopping for a herbicide, look on the label for "Metsulfuron Methyl".
What causes weeds in St. Augustine grass? ›If allowed to, St. Augustine grass could overtake and kill most shrubs in your yard. Most weeds appear because of improper cultural practices such as mowing too closely or infrequently, improper fertilization or irrigation. These are the primary causes for thin or weak turf.
How do you identify weeds in St. Augustine grass? ›
- Examine the grass stems. St. ...
- Look at the leaves. Broadleaf weeds are easily distinguished from grass leaves. ...
- Use the soil condition to help identify the most likely weeds. Annual and perennial grasses grow in St.
- Field Bindweed. Field bindweed is a twining vine that can cover gardens and shrubs in no time. ...
- Burdock. Great burdock flowers look much like thistle blooms. ...
- Ground Ivy. ...
- Canada Thistle. ...
- Johnsongrass. ...
- Mugwort. ...
- Nutsedge. ...
- Poison Ivy.
When it is actively growing, hand pull if you can or use a non-selective herbicide such as glyphosate or glufosinate as a spot treatment. Remember that these products will also kill St. Augustinegrass so they should be used sparingly. Crabgrass growing in turf.
What do landscapers use to kill weeds? ›Some of the best chemicals for pre-emergent weed control include trifluralin, bensulide, DCPA, dichlobenil, oryzalin, and simazine. These are the active compounds that lawn companies use to kill weeds before they germinate.
How do you fix a yard full of weeds in Florida? ›- Consistent Mowing Schedule. ...
- Pull Up Random Plants. ...
- Block Out the Sun. ...
- Apply Pre-emergent Fertilizer. ...
- Post-emergent Herbicide. ...
- Maintaining Thick & Healthy Turf. ...
- Broadleafs. ...
- Grasses.
- Boiling water is a natural way to kill weeds. Heat water to at least 200 degrees and pour directly onto the weeds. ...
- You may be able to prevent, control or kill certain types of weeds using products around your house such as dish soap, epsom salt or apple cider vinegar.
- Boiling water – Pouring boiling water on areas with dollar weed will quickly kill the plants. ...
- Baking soda – Some people have had luck with using baking soda for killing dollar weeds. ...
- Sugar – Others have found success with dissolving white sugar over the weed.
How to Get Rid of Dollarweed (4 Easy Steps) - YouTube
How often can atrazine be applied? ›Some misled gardeners will use weed and feed in spring and then apply an atrazine spray before summer. The form of the application doesn't matter, only two applications of the active ingredient are supposed to be applied per year. Overuse can stress the lawn and nontargeted plants.
What is the best thing to put on St. Augustine grass? ›The best fertilizer for St Augustine grass is any fertilizer that has one pound of nitrogen for every 1,000 square feet of sod. Fertilizing every two months is ideal unless you apply slow release fertilizer that can be spread every 10 weeks.
Will St Augustine choke out weeds? ›
If you live in a warm climate, you've got two great options for a lush lawn. Bermuda and St. Augustine grasses are both thick and great at choking out weeds.
Does St. Augustine grass get weeds? ›You will find both broadleaf and grassy weeds growing in your St. Augustine grass. Broadleaf weeds are easy to spot because they do not look like grass. This makes them stand out.