Will Weed and Feed Kill Grass Seed? When to Plant and Spray Many gardeners often find themselves unsure of how long they’re supposed to wait until they can apply weed and feed to their lawns Do I Weed & Feed or Plant Seed First?. You can sow grass seeds now and kill weeds later with a post-emergent herbicide or kill weeds now with a pre-emergent herbicide and plant the seeds later. Weed-and-feed fertilizers are specially formulated combinations of turf fertilizer and herbicides that you apply either … This is a big question in early spring: “My lawn needs everything what should I do first, put down seed or kill my weeds? The reason why this question is tricky is because many of the weed controls will harm new grass seedlings. Here are your best two options: Do you have less than 75%…
Will Weed and Feed Kill Grass Seed? When to Plant and Spray
Many gardeners often find themselves unsure of how long they’re supposed to wait until they can apply weed and feed to their lawns after planting grass seed. Conversely, the issue may be how long one’s supposed to wait to plant grass seed after spraying weed and feed. For both concerns, the answer largely revolves around the type of herbicides found in different weed and feed products.
Can you put weed and feed on grass seed?
You may be having an irresistible urge to spray weed and feed on your recently overseeded turf after spotting one or two weeds sprouting on the lawn. However, the growing seedlings will not be able to survive the strength of the herbicide. If you’re planning to use a weed and feed product with a post-emergent herbicide on your growing turf, wait until the grass roots anchor deeper into the soil and the lawn is established.
Also, some weed and feed products are non-selective, pre-emergent herbicides targeted at preventing weed seeds from sprouting. As such, when they’re applied on a recently seeded lawn even before the grass seeds germinate, they’ll kill the weed seeds as well as the grass seeds.
To control weeds on lawns before the new grass is established, consider alternative measures like spot treatments. You can also manually uproot the weed plants if the infestation is still in the early stages.
Mowing also helps to control weed growth in newly-established lawns, as the grass grows stronger and crowds out more weeds. In fact, it’s advisable to refrain from spraying weed and feed on your new turf until after the third mowing. By then, the grass will be strong enough to withstand herbicides.
However, even then, you should only use a post-emergent, selective weed and feed product. These will easily kill broadleaf weeds like dandelions and clover without harming your turfgrass. Pre-emergent herbicides won’t work on already existing weed plants, while non-selective/systemic herbicides will kill both the weeds and your growing turfgrass.
When to plant grass seed after weed and feed?
The best time to plant grass seed after applying weed and feed depends on whether the weed and feed used contained a pre-emergent or post-emergent herbicide. For weed and feed products containing post-emergent, systemic weed killers, you can plant grass seed as soon as two weeks after application.
That’s because systemic herbicides don’t leave any residue in the soil that might harm seeds grown a few days after. They’re instead absorbed into plants via the leaves and roots, killing the whole plant within 7 days. Common examples of systemic herbicides include glyphosate and pelargonic acid.
Pre-emergent herbicides, on the other hand, are formulated to inhibit seed germination by forming a chemical barricade atop the soil. Thus, if you plant your grass seed soon after applying a weed and feed with a pre-emergent herbicide, they won’t sprout as the herbicide will still be in the soil.
To seed your lawn after using a pre-emergent weed and feed, you may have to wait between 1-6 months, with 2 months being the average wait time. This is due to the wide variation in the duration it takes for different types of pre-emergent herbicides to degrade in the soil. A herbicide like 2,4-D decays in as soon as four weeks, but you may have to wait for six months to plant grass seed on a lawn treated with Atrazine herbicide.
Take note, though, that there are some types of weed and feed products that can be used to suppress weed seeds without affecting grass seed. These products usually contain siduron, a pre-emergent herbicide that also boosts germination of grass seed. If your pre-emergent weed and feed contains siduron as the primary active ingredient, you can sow grass seed right after application.
Note: Always read the labelling on your weed and feed for information on how long you should wait to plant grass seed post-application. The types of herbicides infused into the product usually determines the manufacturers’ wait time recommendations.
How long after seeding can you spray for weeds?
It’s not uncommon to find weeds sprouting and growing on your lawn alongside your new grass seedlings. The right time to spray selective weed and feed on your lawn after seeding is after mowing three times. At this stage, the grass is mature enough to withstand the harsh chemical herbicides inside the weed and feed.
You can also spray a pre-emergent weed killer if the weed infestation is still in the earlier stages. When you start to notice weeds on your new turf, it’s a sign that more weed seeds are present in the ground and are about to germinate.
You should spray a pre-emergent at least 14 days after seeding, after the grass seeds have germinated into seedlings. As such, you’ll be targeting only the weed seeds that haven’t yet sprouted, and not your grass seeds.
Note: Never use a non-selective weed killer on your new lawn, no matter how mature the grass looks, as it will kill all plants it comes into contact with including the grass.
Weed Control Tips after Seeding a Lawn
You can keep weeds out of your lawn after seeding by adopting the proper watering, fertilizing, and mowing practices. Doing so helps your turf grow stronger and stay healthy enough to choke out weeds.
Do I Weed & Feed or Plant Seed First?
You can sow grass seeds now and kill weeds later with a post-emergent herbicide or kill weeds now with a pre-emergent herbicide and plant the seeds later. Weed-and-feed fertilizers are specially formulated combinations of turf fertilizer and herbicides that you apply either before you plant grass seeds or on established lawns.
You apply pre-emergent herbicides before weed seeds germinate, typically in the spring. Pre-emergent herbicides do not prevent weed seeds from germinating; they suppress the development of weed roots as they germinate. They’re usually effective for two weeks to three months, depending on the formulation, and you have to water the lawn after applying for the herbicide for it to be effective. There are pre-emergent herbicides to kill both broadleaf weeds and weedy grasses. You can apply them before you sow your grass seed. If you apply a pre-emergent herbicide that kills weedy grasses, you have to delay sowing your lawn seed.
Post emergent herbicides kill weeds after they appear. Some post-emergent, systemic herbicides that you can apply directly on lawns only kill weedy grasses, while others only kill weeds with broadleaf weeds. Contact herbicide such as those including the active ingredient glyphosate kills on contact. To use one of those on a lawn without killing the grass you have to daub it on individual weeds.
Pre-Emergent Weed-and-Feed Fertilizer
Fertilizers containing pre-emergent herbicides selectively prevent certain kinds of weeds from finishing their germination cycle. There is no point applying this type of weed-and-feed mix after weeds are growing on your lawn. You have to apply it early in the growing season before weeds appear. Make sure the pre-emergent herbicide in the fertilizer kills the kind of weeds that have plagued your lawn in the past. You might apply a starter fertilizer containing a pre-emergent herbicide before you sow your lawn seeds.
Post-Emergent Weed-and-Feed Fertilizer
Post-emergent weed-and-feed formulations kill selective weeds that are already growing in your lawn. Make sure that the herbicide in the formulation you buy kills the type of weeds that are growing in your lawn. Most weeds make their appearance in the spring, the best time to apply weed-and-feed fertilizer.
What’s First: Feed, Weed or Seed?
This is a big question in early spring: “My lawn needs everything what should I do first, put down seed or kill my weeds? The reason why this question is tricky is because many of the weed controls will harm new grass seedlings.
Weed, Feed or Seed?
Here are your best two options:
Do you have less than 75% good grass with bare spots larger than a few inches in diameter?
Answer: If lots of larger spots, then seed this spring. Be sure to use a special Starter Lawn Food plus Weed Preventer that is compatible with grass seed (the regular crabgrass preventers will keep grass seed from growing). If you do not prevent weeds when you seed, you are likely to be very disappointed as crabgrass and other weeds will germinate and choke out your good grass before it has a chance to take hold. A machine called a slit-seeder will help make sure the grass seed comes in contact with the soil. You just select the Turf Builder Grass Seed blend that is right for your conditions, such as sun, shade, heat-tolerant, etc. If you only have a few bare spots to take care of, consider Scotts EZ Seed. I think this is the best bare spot repair product we have ever sold! Spread the Starter Lawn Food plus Weed Preventer after you put down the seed. Feed your lawn again in one month after seeding with Turf Builder Lawn Food. Once your new grass has been mowed 4 times, you can kill weeds with Ortho Weed B Gon MAX plus Crabgrass Killer OR Roundup For Lawns.
Do you have more than 75% good grass however your lawn is thin and weedy without widespread bare spots?
Answer: If you have more than 75% grass, you may be surprised how your good grass will fill in with four feedings a year at 6 to 8 week intervals. With this option you skip spring seeding (you can always seed in fall if your lawn still needs it). Here is a schedule for the year: Feed your lawn now with Scotts Turf Builder with Halts Crabgrass Preventer. In 6 to 8 weeks after your first feeding, feed again with Scotts Turf Builder Weed and Feed if you have lots of weeds or if you only have a few weeds, your second feeding can be Turf Builder Lawn Food and spot treat your weeds with Ortho Weed B Gon MAX plus Crabgrass Killer OR Roundup For Lawns. Put down Scotts GrubEx sometime in May or June. In 6 to 8 weeks after your second feeding, feed again with Scotts Turf Builder with SummerGuard to control insects. In 6 to 8 weeks after your third feeding, in late summer/early fall, feed with Turf Builder Lawn Food.
If you have questions during the year, the Scotts Help Center folks will be happy to help you.