One of the best ways to keep your yard weed-free is using a pre-emergent herbicide.
When you apply a pre-emergent to the ground at the right times of the year, you can prevent weed seeds from developing into big, nasty, unwanted plants. And stop them from taking over your lawn and garden beds.
But there are many different types of pre-emergent herbicides. So in this article, we take a look at each type and give you the information you need to choose the right one.
Let’s dive in!
Liquid Pre-emergent Herbicide
Pre-emergent herbicides come in liquid or granular form. Liquid pre-emergent herbicide has two main advantages over granular pre-emergent herbicide.
Firstly, it’s quicker to spread over a large area. And secondly, it’s easier to get even coverage. This is important, because without even coverage patches of weed growth will occur.
If you have a large area, I recommend using a liquid pre-emergent herbicide.
Other advantages include:
- The ability to work very precisely. It’s easy to spray a liquid between patio and paving stone cracks. And in raised garden beds.
- Liquid pre-emergent herbicide requires less water for activation and to help it soak into the ground than granular.
- A small amount of concentrated liquid pre-emergent goes a long way after dilution. So it’s often economical, as a bottle lasts the average homeowner a long time.
Granular Pre-emergent Herbicide
Granular pre-emergent herbicides have some advantages as well:
Granules are easy to use. You can use them straight from the packet without needing to mix them with water. Although you will need to take time to calibrate your spreader to make sure granule release happens at a steady rate.
Are you applying pre-emergent herbicide to your flower beds?
If so, then granular pre-emergents have an advantage over liquid pre-emergents. Because although it’s easy to spray the area with liquid pre-emergent, you also run the risk of causing damage to herbaceous ornamentals if the spray gets onto them.
Granular herbicide is easier to apply to the ground around flowers. And then you can water this type of weed killer into the soil without getting it onto plant foliage.
Chemical Pre-emergent Herbicides
The majority of pre-emergent herbicides are synthetic chemicals. There are many pre-emergent chemicals to choose from.
Each chemical has a list of weeds that it’s effective against. So it’s a good idea to identify the weeds you’re trying to prevent. Then you can choose the right pre-emergent for the job.
You should also check that the pre-emergent is safe to use on your type of turfgrass. Or that it’s suitable for use in garden beds.
These are some of the most common pre-emergent chemicals:
Pre-emergent Herbicide Examples
Prodiamine is good for preventing grassy weeds and broadleaf weeds. Some of the common weed species it controls include chickweed, dandelions, and plantain.
Prodiamine is also a good crabgrass preventer. And you can use it in the fall to control annual bluegrass (Poa annua).
Trifluralin is one of the safest pre-emergent herbicides to use in flower beds. But it’s not one of the strongest.
You can use trifluralin to control a range of grassy and broadleaf weeds. And it’s also used in agriculture to prevent weeds from growing around fruits, vegetables, and nut crops. Because, unlike many other pre-emergent herbicides, trifluralin is safe to use around edible plants.
You can use dithiopyr to control problematic annual grasses and grassy weeds such as crabgrass and goosegrass. It also provides early post-emergent crabgrass control.
You can also use dithiopyr to prevent broadleaf weeds. But it’s not always effective. And you may find that you need to increase the concentration you use.
You can use isoxaben for controlling annual broadleaf weeds such as henbit and bittercress. And it does a good job of controlling perennial weeds that spread by seed, such as dandelions and white clover.
But this pre-emergent is not as effective against grassy weeds such as crabgrass, carpet grass, and annual ryegrass.
Homeowners often use benefin on residential lawns to control a range of grassy weeds. Including goosegrass, Poa annua, crabgrass, and ryegrass.
You can also use it for controlling broadleaf weeds such as chickweed, purslane, pigweed, and lambs quarter.
Benefin is another pre-emergent herbicide that you can use in your vegetable garden. It’s safe for occasional use around edible crops.
You can use oxadiazon to prevent annual grasses and grassy weeds such as crabgrass, Poa annua, and goosegrass.
It also controls many species of annual broadleaf weeds. Including woodsorrel, bittercress, and willowherb.
Do you have brush vines and brambles on your property? Oxadiazon can take care of those as well.
But there are better pre-emergents you can use if you’re trying to prevent spurge, chickweed, or pearlwort.
Oxadiazon also offers early post-emergent control of some weeds. But it’s not recommended for use on home lawns.
Organic Pre-emergent herbicides
The main organic pre-emergent herbicide is corn gluten meal. It raises the protein content of the soil. And in doing so inhibits seedling root development.
You use corn gluten meal in a similar way as granular pre-emergents. Spreading it evenly over the target area. And watering it into the soil.
But it doesn’t work for all weeds and there’s debate over its effectiveness.
Corn gluten meal also contains nitrogen. So it will fertilize your lawn at the same time as it prevents weeds. But if you get the timing wrong and the weed seeds have already germinated, you will be fertilizing them as well.
Other notable drawbacks are that it can attract insects. And it works out more expensive than chemical pre-emergent herbicides.
Pre-emergent fertilizer combines a chemical pre-emergent herbicide with fertilizer. Allowing you to kill 2 birds with 1 stone.
The timing is important with this type of pre-emergent herbicide. The best time to lay down pre-emergent is not always the optimal time to be applying fertilizer. You need to consider your lawn care schedule and the type of weeds you’re preventing before deciding to use pre-emergent fertilizer.
How To Choose A pre-emergent Herbicide For Your lawn
Pre-emergent herbicides are not a one-size-fits-all product. To find the right one, you need to consider some questions:
What type of lawn weeds are you trying to prevent?
Different pre-emergent herbicides are good for controlling different types of weeds. Check the product label to make sure it can take care of your problem.
Where are you using the pre-emergent?
The ideal pre-emergent to use in your vegetable garden or flower bed might be different than the one you choose for your lawn. But most general-purpose pre-emergents can do both.
What tools do you already have?
You’ll need to spread the pre-emergent. If you already have a garden sprayer, it makes more sense to choose liquid over granules.
How big an area are you treating?
It’s quicker and easier to use a liquid to treat large areas.
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