Weed control is usually high on the to-do list for spring gardeners here in San Antonio. While a regular schedule of fertilizing your turf can help immensely in choking out weeds, but sometimes extra help is needed for these pesky lawn invaders. Treatment for weed control and prevention is a timely garden task. Weed pre-emergents prevent the seeds of weeds from germinating. Applying weed pre-emergents is one of the best ways to eliminate weeds and prevent them from stealing your turf’s vital nutrients out of the soil.
When To Apply Pre-Emergent Weed Control Products
- Mid to Late February: Keep a watch on the weather. If cold weather is prolonged, you’ll need to wait awhile for a warm break to apply for spring. Apply pre-emergent granular herbicides that are formulated for preventing the common grassy weeds that pop up in spring.
- May-Early June – One more application of a grassy pre-emergent product can keep fall weeds at bay. Hi-Yield Turf & Ornamental Weed & Grass Stopper with Dimension, Hi-Yield Crabgrass Control .
- Mid September – Early October – After the first decent rain in September, you can apply a pre-emergent granular herbicide with ingredients meant to ward off broadleaf weeds that we experience popping up in late winter/early springtime.
7 Examples of Weed Control Pre-Emergent Products
- Crew
- Hi-Yield Turf & Ornamental Weed & Grass Stopper with Dimension
- Hi-Yield Crabgrass Control
- Gallery (focus on broadleaf weeds)
- Bonide Weed Beater Complete (Pre and post emergent product in one. Great product when used early in spring. Later applications in warm weather can turn turf yellow for awhile, but this is easily remedied through fertilization of turf).
- Fertilome Crab Grass Preventor Plus Lawn Food (20-0-3 with Dimension, good weed and feed for early spring). We generally don’t recommend Weed and Feed products, but this one is ok for early spring.
- Organic Weed Pre-Emergent: Espoma has an Organic Weed Preventer made with corn gluten meal.
Post Emergent Weed Control
Weed control post emergent products are applied after the weeds have already developed. These products usually consist of a liquid form applied by a spray applicator. Generally, we don’t recommend these types of products but for spot application to weeds.
It’s imperative to be very selective when choosing a post emergent. Make sure the label clearly states that they are safe for your particular variety of turf. Even if it is labeled safe for your turf, keep in mind that you shouldn’t be spraying these products in the heat of the day as they could still cause your lawn to burn. Only spray during early morning or late evening.
4 Examples of Weed Post Emergent Products
- Ortho Weed B Gone For Southern Lawns (liquid formula)
- Hi-Yield Atrazine Weed Killer (liquid formula)
- Bonide Weed Beater Complete (Granular pre and post emergent product in one. Applied in warm weather can turn St. Augustine yellow for awhile, but this is easily remedied through fertilization of turf).
- Hand Pulling is not the most fun way to rid yourself of your weed problem, but it is the cheapest; and when employed early, can be one of the most effective ways to control weeds after the fact. A little elbow grease and some extra time pulling weeds while they are young and few, will save you the pain of pulling weeds when they have deep tap roots and are taking over. Old forks and thrift store bbq utensils can work wonders at pulling those stubborn weeds.
Visit our lawn care page for more helpful info on building healthy turf.
~The Happy Gardener, Lisa Mulroy
I applied pre-emergent mid February but then we had snow storm and I ended up with weeds. Should I re apply the pre-emergent or use weed killer? If so what is best. I tried pulling but a bit too any. Thamk you.
Hi Emma,
The weeds that you are seeing now are not from weeds that start to germinate in spring. The weeds you are seeing right now are winter weeds that germinated end of summer/beginning of fall. These weeds generally die out with hot weather. You can mow and bag so that they don’t drop seeds, or pull, or you will need to spot treat weeds with a spray like Ortho Weed B Gone or something like that, but make sure that the label says it is safe for your type. The weeds you are preventing right now are the ones that pop up in fall. Pre-emergent only prevents seeds from completing their germination process. It won’t kill weeds that were already growing.
I have Bermuda and zoysia that come up in my flower beds. Other than pulling constantly, is there a way to treat without killing my plants? Thank you in advance
Do you already have a barrier between the grasses and the flower beds? A physical barrier like some type of edging? Are your flower beds already mulched? These are two things that definitely help with control of weeds and grass invading your beds.
A few suggestions for controlling grass in flower bed are: Fertilome Over the Top 11 Grass Killer can be applied to the grass without harm to desired plants, as well as Monterey Grass Getter, and Ortho Grass B Gone. ALWAYS ALWAYS read the labels on any herbicide and follow the instructions exactly as advised.
My St Augustine is already overtaken with crab grass!! Every year I pull a lot of crab grass at the beginning of the season until the st Augustine is in enough to choke it out, but I’ve never had this much this soon. I need to figure out something to use to prevent it and when to apply it. Any recommendations?
Hi Kellye,
Oh yes, we feel your pain. Crab grass is no fun. AgraLawn CrabGrass Killer is a post emergent product that kills crabgrass from the roots. So this would be used to kill the crab grass that you CURRENTLY have. You can use it yearround for spot treatment control. BUT… you need to start applying a pre-emergent product in both early spring AND early fall to prevent the crabgrass from even getting started. Ike’s Sandbur & Crabgrass Preventer, or the product CREW can be effective pre-emergents and contain ingredients that control crab grass as well as a slew of other weeds. I see you posted on the weed prevention blog so hopefully you saw the schedule for when to apply pre-emergents (hint…it’s now to mid March), but you might want to treat for the existing weeds and then follow up quickly with the pre-emergent so you are able to cover areas that could be under the existing weeds.
Mowing and bagging, though not fun, also helps get rid of some of those seed heads and prevents further spreading. Hope this helps!
This spring, our yard is over-run with the “Velcro-plant” weed. We’ve never seen this huge an invasion before. We are hand pulling them and read that they spread by seed. Was there something that triggered it this year? And how can we prevent a recurrence?
Hi Susan,
Ugh, this weed can sure be a pain. You are doing right by hand pulling as much as you can, but the problem is that it creates so many seeds that it’s difficult to eradicate completely. The MOST important thing is to make sure you apply a pre-emergent weed control (for broad leaf weeds) in late August to mid September. Bedstraw (velcro plant) is a winter weed that germinates in fall and grows in spring. You want to try to prevent the seeds that it is producing now, from sprouting in fall. What you can do now: keep pulling to try to get them out before they flower and go to seed (though we see that is already happening in some areas), use a steel rake to rake and twist once to yank it out (might save some backache of being on your hands and knees pulling it), or use a post-emergent. I hesitate to say to use a post emergent because you have to be really careful and only use one that is safe for use on the type of turf that you have. READ the labels! If you do choose to use a post emergent weed killer, add a surfactant to it (a few drops of dish liquid will work) so that it sticks to the leaves. Otherwise, it will burn out in your lawn when temps hit 90. But the seeds will still be lying in wait, so make sure to use pre-emergent in fall to prevent another invasion. Hope this helps!