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best grass seed plus weed killer

Chemical weed preventers, also called preemergent herbicides, are usually granules or liquids, but both require water to work. As the preventer soaks into the ground, it leaves a residual film in the top 1-inch of soil. Because most seeds germinate at or just below the soil’s surface, these preemergent herbicides remain active against any germination processes for up to four months, depending on the chemicals involved. Organic weed preventers work in a similar way. With many weeds being members of the grass family, all seeds, including desired lawn species, fail to germinate and sprout after you’ve used a weed preventer.

Spreading seed is an inexpensive way to grow a lush lawn, but exposed soil between germination and establishment makes it vulnerable to weeds. Although chemical weed preventers have different mixtures and instructions, you should not apply them while seeding or immediately afterward. You must allow one to four months between applying this type of chemical and spreading seed.

Preventer Science

Cool-season grasses are usually seeded, as opposed to warm-season grasses that usually need to be grown from sod or plugs. Because cool-season grass seeds germinate best in fall, apply your chemical preventer in spring to actively kill off weeds in spring and summer. In general, temperatures between 65 and 70 degrees Fahrenheit are good for weed preventer application. Hot days often cause the chemicals to vaporize into the atmosphere, reducing their effectiveness. By the time fall seeding weather arrives, the chemicals are no longer active and the grass seeds will be able to sprout.

Even if you time your weed preventer and seeding periods correctly, you need to do the job right to get an even lawn with no bare patches. Apply seeds uniformly across your yard using a drop spreader on a mild fall day. Spread up to 1-inch of organic mulch over the seeds to conserve moisture and encourage germination. Water the seeds at least twice a day for short, 10-minute sessions. You do not want to wash away the seeds, but they need consistent moisture to grow. Hand pull any weeds that appear while the grass seedlings develop. Do not apply any chemicals for weed control.

Avoid the need for weed preventers by keeping your lawn healthy. Once established, only water your turf once a week during the growing season. Up to 1 inch of water during this watering session allows roots to search deeply for moisture to create strong grass. Shallow grass roots die in stressful conditions, like drought, and allow weeds to grow in thinned spots. Allow your turf to grow to a healthy height as well, typically between 1 and 3 inches, depending on the species. Long grass blades mean the grass can produce enough energy to stay healthy and compete with weeds. In short, healthy and well-maintained grass has less problems with weed growth.

In general, grass species are divided into two categories: warm season and cool season. The seasons do not refer to the time of year, but the climate and average soil temperature range.

To grow a lush lawn, your soil needs to have essential nutrients. Fertilizers temporarily add nutrients to the soil. Fertilizers denote their nutrient ratios as NPK. This denotation represents the percentage of nitrogen (N), phosphorus (P), and potassium (K) in the product. This is how the nutrients help grass:

Ahead, read our guide to understanding weed-and-feed products, as well as the details on our top-favorite picks among the best weed-and-feed options available.

Type of Turf Grass

There are at least 11 states that ban phosphorus fertilizer use or sale. Luckily, many lawn weed and feed products available have adapted to this and have removed phosphorus from the product. Don’t worry—the weed and feed will still green up and thicken the grass without the additional phosphorus.

Weed preventers, or preemergent weed killers, block weed seeds that are already in the soil, like crabgrass, poa annua, chickweed, and henbit, from germinating. Identify the type of weeds that are infesting your lawn and then make sure you choose a product that’s made to take care of it.

Some weed-and-feed options out there feature slow-release formulas so you don’t have to fertilize as often. However, to achieve good results plan on treating your lawn at least once every 8 weeks from the start of spring.

To find out exactly what nutrients your lawn needs can be determined by conducting a soil test. You can either purchase a test to use at home or take a soil sample to your local cooperative extension testing office.

So if you passed the test on this part and are seeding Kentucky Bluegrass for example, then you need to next consult table 4 which is going to give you the timing of seeding both before and after.

So to be clear – you can apply this up to seeding, but once the seed germinates (4-5 days for rye, up to 21 days for bluegrass) you should NOT apply it to weeds until the new turf has been mowed 2-4 times or 4 weeks, whichever is longer. This is because baby grass is weak and can’t withstand/tolerate mesotrione .

Second, I respect the green industry and the lawn pros who make their living doing this day in and day out. When you use professional formulations of products like the ones listed here, I now view you on their level and that also means we need to stay within the bounds of the label which is the law. If you see YouTubers or social media influencers out there not following the label, including me, you should call them/me out. Everyone makes mistakes here and there, but it’s their reaction to being called out that truly shows their intent. I like to think everyone means well and is willing to admit when they are wrong.

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You can spray it anytime you want leading up to seed day, and on seed day, but once your seeds germinate, you should NOT spray it again until the new gras has been mowed 2-4 times or 4 weeks whichever is longer.

So there you go, all about reading labels for seeding – hope this has helped you and that your seeding will be successful this season!

This is where it sometimes gets confusing so follow along with me.

First off, when I worked for TruGreen ChemLawn, Quincept was our go-to weed control for summer and I remember that every year that right around 3 weeks before overseeding time we would get a memo telling us to cut off the Quincept use. The memo would come early but would read “stop spraying Quincept 2 weeks prior to starting your overseedings for customers.”