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how long after weed killer can you seed

Note on Details:

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.

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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.

Reading the Label – Quincept – New Farm

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.”

If the “lawn” is more weed than grass, I would kill everything and start over. If you take that option, Ortho is the wrong product because it isn’t supposed to kill grass.

The next few suggestions are the most important thing you need to remember so this doesn’t happen again; never mow lower than 3″! 3 1/2inches is best. Always sharpened blades. Always changing directions with each mow. Bag your clippings and use them in your compost pile or dumped on top of weeds in the back of your plant beds. Make sure the grass is no shorter than 3″ after mowing!

5 Answers 5

When you make a curve keep that radius going until you decide to change to an outside curve. The radius size doesn’t matter as long as you keep it consistent until you change the direction of the curve. Use string, a stake, even a hose works well. Make a 6″X6″ trench all along the edge of your lawn. Use a flat shovel. Throw the grass and soil up on your beds. Simply redo your edges in the spring with a shovel and/or use a string trimmer. I’d buy one of these, a Stihl. Always wear eye protection and watch where the debris and rocks fly.

The next critical thing you need to do once per year is aerating! Pulling plugs of sod and soil out of the lawn then allowing them to stay where they fall. This is another piece of equipment to easily rent. Share this expense with your neighbors and have an annual PARTY!

Cool season grasses have to be watered deeply then the soil needs to be allowed to dry out. As the moisture is used and evaporated from the surface the roots grow deeper to reach the moisture deeper. 4 to 6″ deep. Watering a little every day is the worst thing one can do for cool season grasses.

Sowing seed after applying a pre-emergence weed killer disturbs the chemical barrier on the soil surface, which means that weed seeds may germinate too.

It makes sense to be cautious about sowing seed after using weed killer. Certain herbicides can harm sprouting seeds and young plants. However, while you must wait several months to sow seed after applying some weed killers, you only need to wait a few days after applying others. The reason for this difference lies in the effect of the active chemicals in the individual products. Read the label carefully and follow all the directions when applying a weed killer.

You can sow seeds in as little as a week or even sooner after spraying glyphosate, a systemic, nonselective weed killer. Glyphosate moves from the leaves to the roots of plants, destroying the entire plant, but leaving no residue in the soil. The chemical affects many types of plants, including weeds, grasses and desirable plants, but after the liquid is absorbed into the plant, it doesn’t pose any further threat. You can safely sow ornamental flower seeds a day after spraying with glyphosate and grass and vegetable seeds, three days after, even though the herbicide takes up to seven days to destroy weeds. If you remove the dying weeds too soon, live roots could remain in the soil, ready to regrow. Another systemic weed killer that doesn’t affect seeds is pelargonic acid.

Warning

Pre-emergence weed killers prevent seeds from sprouting. They create a chemical barrier on the soil surface that suppresses seed development. What this means is, if you sow your own seed after applying a pre-emergence weed killer, the seed isn’t likely to grow. However, some pre-emergence products only affect grassy weeds, so you can safely sow most vegetable and flower seeds after applying these herbicides. The same doesn’t apply to reseeding or overseeding your lawn. Grass seed won’t sprout until a pre-emergence weed killer has decayed and become ineffective. For example, it isn’t safe to sow lawn seed until four months after applying a crabgrass preventer.

Many selective weed killers leave little or no trace in the soil, and they target certain plants while leaving others unharmed. Generally, these types of herbicides destroy either grassy weeds or broadleaf weeds. You can safely sow most seeds in your vegetable or flower patch a day after applying selective herbicides, such as sethoxydim, clethodim and bentazon, for grassy weeds. These herbicides only affect your desired plants if the plants belong to the grass family. For lawns, herbicides that destroy broadleaf weeds are effective, but it isn’t safe to reseed until a month after applying these products, unless the label states differently.