Lawn Weed Control… Liquid vs. Granular (Dry) – Which is Better?
When shopping for a lawn care service or to Do-It-Yourself, you’ll likely notice two options for weed control – liquid and dry (or “granular”) formulations. Home & Garden stores often sell D.I.Y. granular weed control products. So which is better?
First – Some information about liquid and granular weed control and how they are applied.
Liquid weed control is just that – the herbicide is mixed in water and is then sprayed with equipment designed for this purpose. The equipment can be as sophisticated as a riding machine that is calibrated to apply extremely precise amounts of the weed control or as simple as a hand-help pump-up can or back-pack sprayer.
The more sophisticated equipment allows the user to apply just the right amount of weed control needed – not too much (which would be wasteful and could damage the grass) or too little (which might not control the weeds).
On the other hand, a pump-up or back-pack sprayer is inexpensive and readily available. These are less accurate but can still be effective when used properly.
Granular (or dry) weed control, on the other hand, looks similar to granular fertilizers. The granules are small pellets coated with herbicide. These products are applied with push spreaders, hand-held ‘whirly-bird” spreaders or, the more accurate, powered spreading equipment.
While some lawn weed control products are designed to stop weeds before they start to grow (for example, crabgrass preventer) this article will compare “post-emergent” lawn weed control formulations – which are intended to eliminate actively growing weeds – like the clover and dandelions you see growing in lawns. Post-emergent weed control must contact, stick to, and be absorbed through the leaf of the weed to be effective. It is worth noting, more resilient weeds may require particular products to be effective.
So what are the Pros & Cons of Granular Weed Control?
- Liquid Weed Control typically needs to be mixed with water. This means measuring the concentrate and mixing it with the appropriate amount of water.
- Granular Weed Control just needs to be put in the spreader and it’s ready to use.
- Winner: Granular Weed Control
- After the mixing is done with the liquid weed control, the application process has a similar level of difficulty. With both materials, you need to be attentive and use the right amount in the right areas.
- Winner: TIE
Both Granular and Liquid Weed Control can be very effective however, remember that the material must stick to the leaf of the weed in order for it to be absorbed into the plant and translocate down to the plant’s root system. These materials are ‘foliar’ weed controls. This means they have to be absorbed into the plant through the foliage (leaves) of the weed.
- The downside to granular weed control is getting it to stick to the weed. These materials work best when applied to wet weeds. Without the surface moisture, the granules mostly roll off the leaf reducing potential control. Rain doesn’t always fall when we would like it to and irrigating the lawn isn’t exactly quick and easy.
- Liquid weed control can be applied when the weeds are wet or dry which makes it a much more versatile option.
- Winner: Liquid Weed Control
Note: Neither product should be applied while it is raining
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Both liquid and granular weed control products are readily available to both professionals and homeowners. While there can be a difference between professional products and home-use products, most granular and liquid weed control products have the potential to control the entire plant, including the roots.
If you’re looking for a quick D.I.Y. method to gain some control of the weeds in your lawn and don’t mind waiting to do the applications until the lawn is wet – granular weed control may be the answer.
Liquid weed control is the go-to product for most professional lawn care service providers. It controls a variety of weeds – quickly and effectively.
According to Purdue University Turfgrass Science, liquid sprays tend to be more successful than their granular counterparts, simply because the liquid formulation is sprayed across the weed’s leaf surface and does not rely on additional moisture to stick to the leaf. Once dried, these liquid products stay on the leaf surface even if rainfall occurs.
If you’re considering a professional lawn care service or looking to eliminate difficult weeds yourself – liquid weed control is generally the best option. The characteristics of the liquid weed control formulations provide more consistent results, especially on the stubborn weeds we often experience in lawns.
Overall Winner: Liquid Weed Control
If you are interested in Green Giant’s services, we would like to answer any questions you have!
Green Giant Home & Commercial’s Lawn Care services control weeds, build the thickness and density of your lawn and protect it from being damaged by insects and disease, providing you with a great-looking, healthy lawn. We offer fertilization, weed control, liming, insect control, and aeration and overseeding. Visit our Lawn Care page for more information.
Green Giant performs: Proper Diagnosis and Treatment of Tree & Shrub Problems, Insect & Disease Control (including Spotted Lanternfly), and Nutrient Management via Deep Root Fertilization to keep your plants healthy and thriving. Visit our Tree Care page for more information.
Green Giant’s Non-Lawn Weed Control services eliminate unwanted vegetation in a wide variety of locations for both residential and large commercial/municipal properties. Areas include fence lines, around obstacles to reduce weed eating, stone/gravel driveways & parking lots, swales, roadside/curbside vegetation management and more. Find more information, visit our Vegetation Management page.
Our full service pest control division provides both Year-Round Service Programs that cover the vast majority of pests that you will encounter and also One-Time Corrective Services for pests such as bees, ants, termites or mice. For more information, visit our Pest Control page.
How Long Does Weed Killer Last In The Soil
Weed killer (herbicide) can be an effective way to get rid of any unwanted plants you may have growing in your yard, but weed killer is normally made up of pretty potent chemicals. These chemicals may not be something you wish to have contaminating plants, especially fruit and vegetables. So the questions “How long does weed killer last in the soil?” and “Is it safe to eat food grown in spots where weed killer has been sprayed previously?” can come up.
Weed Killer in Soil
The first thing to realize is if the weed killer was still present, chances are your plants would not be able to survive. Very few plants can survive a weed killer chemical, and the ones that do are either genetically modified to do so or are weeds that have become resistant. Chances are, the fruit or vegetable plant you are growing isn’t resistant to weed killer, or most herbicides in general. Many weed killers are designed to attack the plant’s root system. If weed killer was still present in the soil, you would not be able to grow anything.
This is why most weed killers are designed to evaporate within 24 to 78 hours. This means that for the most part, it is safe to plant anything, edible or non-edible, in a place where you have sprayed weed killer after three days. If you want to be extra sure, you can wait a week or two before planting.
In fact, the majority of residentially sold weed killers are required by law to break down in the soil within 14 days, if not sooner. Take glyphosate, for example. This post-emergent, non-selective herbicide generally breaks down within days to weeks depending on the specific product you have.
(NOTE: New research has indicated that glyphosate may, in fact, remain in the soil longer than initially thought, up to at least a year. It is best to avoid use of this herbicide if at all possible unless absolutely necessary – and then only with caution.)
Weed Killer Residue Over Time
While all herbicide residue degrades over time, it is still dependent on several factors: climatic conditions (light, moisture, and temp.), soil and herbicide properties. Even if there are some residual, non-plant lethal chemicals left in the soil after the weed killer has evaporated or broken down, these chemicals most likely will have been leeched away after one or two good rainfalls or waterings.
Still, it can be argued that these chemical herbicides linger in soil well beyond a month, or even years, and it is true that residual sterilants, or “bare ground” herbicides, remain in the soil for long periods. But these stronger weed killers are normally limited to agricultural specialists and professionals. They are not meant for home use around gardens and landscapes; therefore, the average homeowner is usually not allowed to purchase them.
For the most part, the chemicals found in weed killers aren’t a problem for the home gardener after they have evaporated. According to many professionals in the field, most of the weed killers used today have a relatively short residual life, as those found to be more potent are typically denied registration by the EPA.
This being said, it’s always a good idea to completely read the directions and warnings on the label of any weed killer or herbicide product you buy. The manufacturer will have provided detailed instructions on how to apply the weed killer and when it will be safe to grow plants in that area again.
Note: Any recommendations pertaining to the use of chemicals are for informational purposes only. Specific brand names or commercial products or services do not imply endorsement. Chemical control should only be used as a last resort, as organic approaches are safer and more environmentally friendly.