It’s important to know a little about herbicides so you can make the best choice for when to apply seed in an area that has been treated for weeds. The most common types of herbicide in weed and feed products are selective and systemic. Selective herbicides target a species of plant to kill while systemic herbicides work by being absorbed though the roots and then transported throughout the plant, killing it from within. Read the bag label to see what kind of herbicide is used in the weed and feed you are considering using or have used. The bag label will tell you how many days you must wait before applying seed to a lawn that has been treated with that product.
Only use a weed and feed if the weed infestation is completely uniform over the entire lawn and all species of weeds targeted will be affected by the herbicide in the weed and feed. This scenario doesn’t occur often, so it is more likely the use of an herbicide and a fertilizer separately will be needed. If the weeds are uniformly spread over the area to be treated, match the appropriate weed and feed product to your grass, the seed you have recently applied or want to apply, and the time of year.
Herbicides can target weeds before they germinate from seed – pre-emergent – or as developed plants – post-emergent. Before you seed, you can use a non-selective, post-emergent herbicide to control any weeds in the area to be seeded. Most of these can be applied up to two weeks before seeding to control any existing weeds. Herbicides should not be used after seeding until the new seedlings are established. Mowing and spot treatments can be used to control weeds until the seeded area is actively growing and requires only maintenance watering. Establishment times vary depending on the type of seed you use and your weather conditions.
Weed and feed fertilizers are often used in combination with seeding. Weed and feed formulations consist of two components: a herbicide to kill weeds and a fertilizer to strengthen the turf. The herbicide will weaken the grass as well as the weeds and the fertilizer will strengthen the weeds as well as the grass. When applying seed over a weed and feed application, remember that some weed and feeds can prevent grass seeds from growing.
It is important to know what kind of grass you have growing or want to have growing. Certain chemicals act differently on different species of grass and weeds. For example, the common herbicide 2,4-D is toxic to some cultivars of St. Augustine grass (Stenotaphrum secundatum), which grows in the area roughly covered by U.S. Department of Agriculture plant hardiness zones 8 through 10. Another common herbicide, atrazine, is potentially lethal to grass when applied in temperatures above 85 degrees Fahrenheit. Use the instructions on the bag of each weed and feed product to determine how it will affect seeding.
Sara DeBerry is a graduate of the University of Florida holding a masters degree in environmental horticulture and a minor in entomology and nematology. DeBerry has been writing for government agencies since 2004 and has published peer reviewed scientific articles during her studies at UF.
Using Weed and Feed.
Types of Herbicide.
Pre-emergent weed and feed is applied in early spring so the herbicide is in place before the undesirable weeds germinate. Pre-emergent herbicide works by inhibiting germination. It must be watered with at least one-half inch of water to move the chemical from the surface into the soil. Post-emergent herbicides, however, must be applied while the weeds are actively growing because for the chemical to work, the herbicide must be absorbed into the plant.
You want a beautiful lawn for your family to enjoy, but it’s no longer enough to just mow it. You have to fertilize, water, kill weeds and then reseed any bare spots. Using a weed and feed product saved you some time, so now you’re ready to plant some grass seed. You may have to wait a bit longer, though, depending on the type of weed and feed product you used.
Since weed and feed products are designed to prevent germination — or to eradicate a living plant — they can, for the most part, have a similar effect on young turf grass. The only exception is the pre-emergent herbicide siduron, which is actually used to assist in seed germination. When using a pre-emergent that does not contain siduron, wait a minimum of two months before seeding. If using a product designed for broadleaf weeds, read the label carefully, because the active ingredient in these post-emergent herbicides have a wider range for the waiting period. Grass can be planted in as little as one month after application for products using 2,4-D to as much as six months for atrazine-based products.
Weed and feed products consist of fertilizers such as nitrogen or potassium, and a pre-emergent or post-emergent herbicide. If the weed and feed is designed for spring application, it contains a pre-emergent. If it is designed for later in the growing season, it incorporates a post-emergent herbicide. Knowing which one you are using is important because the herbicides affect plants in significantly different ways.
When you are ready to seed your lawn, use a garden rake to remove debris and to break up the surface to ensure the seed comes into contact with the soil. Broadcast the seeds in two directions to ensure complete coverage, and water the ground lightly and often for up to two weeks — keeping the soil moist. Once seedlings have established, gradually reduce the frequency of the watering, but lengthen the amount of time per watering. This will encourage a deep root system for your grass.
Why You Wait.
Weed and Feed.
How They Work.
Gardeners can also apply this weed killer at certain times of the year, depending on the kind of grass they have. Along with this, you can find it affects how quickly you can get to reseeding your lawn.
Do this daily, until new grass blades grow. At this point, you can reduce watering to twice per week. The depth also only has to be one inch deep.
One of the reasons gardeners seed their lawns is that thick grass can help to retard the growth of weeds.
Take your garden hose, but be careful not to drag it across your lawn. Water your lawn to a depth of two inches. (Learn How To Plant Poppy Seeds)
Rake your lawn so you can remove dead grass and roots. Preemergent’s should take care of any weeds before they take hold. You need to apply this in the spring before the temperature reaches the range of fifty Fahrenheit and above.
How Long After SprayingCan I Plant Grass Seed?
Spot weeding will be required with a spot weed killer in the spring and summer. For a well-established lawn care practice, you may see you don’t need to do an all-over treatment for several years.
No products found.
The manufacturers claim there is no leeching into the soil, and any of the chemicals that washes into the earth won’t last for more than 24 to 48 hours.
If you sow feed on your lawn first, you will need to let the feed work for one to two weeks before you treat the weeds.
For the most part, the chemicals found in weed killers aren’t a problem for the home gardener after they have evaporated. Most weed killers used to come with a relatively short residual life.
The solution is pre-mixed, so it is a matter of spraying. This may come with a spraying wand depending on the pack, and it does help with directing the herbicide where to go.
Re-seeding your lawn can be a waste of time, and you may not find out until it is too late. (Read Can Grass Seed Go Bad)
However, some single-use weed killers, you can use in combination with another. By doing so, you can treat your lawn twice in one year. Doing this does apply to the entire lawn coverage and not spot treatments.
Add half of the recommended quantity of seeds to your seed spreader.
Getting any of these wrong can ruin your lawn, or you can find you sow your lawn, and the seeds don’t grow because of weed killer traces.
Items You Need.
One of the crucial things for gardeners who want to use it on their lawn is how they use it, and how often they apply it.
If you are planting cool-season grasses or turf, the best time for doing so is in the fall or early spring. Warm-season grasses, on the other hand, you ought to plant grass seed before August or September.
The issue with Roundup is it is a non-selective herbicide, meaning gardeners do need to take care of where they spray it.
You also need to spread a thin 1/4-inch layer of topsoil across the top of your lawn and make sure it works its way between the current blades of grass.
If you apply Roundup in the fall, you will need to wait until the following spring before you seed warm-season grasses.
If these products are used, then growth can be almost non-existent for nearly four months.
If you are planting cool-season grass, you proceed with seeding your lawn after using Roundup in the summer, in October once the weather cools.
Lawns and Pre-Emergent Herbicides.
One other thing to do is be sure not to water your lawn after you use weed killing products. This dilutes it and prevents it from doing its job.
Moving backward and forward in rows, walk across your lawn. Once you have done this in one direction, add the remaining half of the seeds. You can now spread these in a perpendicular pattern to the first to complete your overseeding.
A period will follow, where you can’t do anything. It is here the weeds should be dying. There aren’t many plants, which are hardy enough to survive a good dose of weed killer, and grass can have a much tougher time.
Tending to weeds comes at precisely the same times when gardeners want to seed their lawn to fill in any thin patches or to ensure they have good growth before the lawn mowing commences.
When spring comes, it is this time when weeds begin to raise their ugly heads. It is a chore that every gardener faces, and can be a frustrating one.
The answer to this will depend on the weed killer you use. You must read the labels at the time of purchase and before use. You can find some weed killers that only require one treatment per year.
In fact, by law, most of the commercially available weed killers you purchase from a local garden center are required to break down in the soil inside two weeks.
Being a systemic herbicide, the leaves of the weeds will absorb Roundup, where it circulates through the weeds until it reaches the roots.