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How Long After Weed Killer Can I Plant Grass Seed

Weeds are a great problem if you are committed to having a picturesque lawn. There are a number of weed killers available in the market and all of them have varying degrees of poison in them.

So, the question is – how long after weed killer can I plant grass seed? When do you plant the grass seeds after you have gone through the process of killing the weeds in the soil?​

Well, there are a number of different options for weeds and for some, you need to wait for about 3 three months. However, there is another set of weed-killing pesticides where you only have to wait for a week before planting the seeds.

The difference lies in the chemical composition of the herbicides used. To make sure that the herbicide being used has the optimum chemical composition, you must check out the label on the bottle.

How Long After Weed Killer Can I Plant Grass Seed?

This question can be easily answered if the chemical composition of the weed killer is known. Let us discuss the different types of herbicides available in the market and the time that we are required to wait before planting the grass seeds.

herbicides - How Long After Weed Killer Can I Plant Grass Seed
via Pixabay

1. Selective Weed Killers

These are very garden-friendly and will make you wait for a month or so before planting the seeds. Examples of such herbicides are bentazon, clethodim, and sethoxydim. These herbicides either destroy broadleaf weeds or grassy weeds.

They affect desired plants only if the plant belongs to the grass family and does not leave any trace on the soil. Such herbicides are pretty effective in killing broadleaf weeds in the case of a lawn.

We would recommend a month, but you can also attempt it sooner according to the directions mentioned on the label of the herbicide.

2. Pre-emergence Weed Killer

These are very efficient weed killers which prevent weeds from growing by killing them in their initial stages. They also affect plants of the grass family. You need to wait for about four months before planting the grass seeds.

The herbicide needs to completely decay and all of its traces need to be removed before planting the grass seeds. If not handled carefully, the grass seed might not grow at all.

After a sprinkling of pre-emergence weed killer, the soil is forced to develop a chemical barrier which prevents further growth of vegetation. Hence, you need to be very careful while planting grass seeds after the pre-emergence weed killer has been used to kill weeds.

3. Glyphosate

This is a systematic, non-selective weed killer. This kills the entire plant by starting from the roots up to the stems. The herbicide does not leave any residue of the dead weeds in the soil.

The weed affects a number of plants such as grass, weeds and undesirable plants. However, the herbicide does not affect other plants once it has been completely absorbed by the soil. It is only necessary to wait just three days before planting the grass seeds.

The herbicide actually takes up to seven days to completely remove the weeds. If you are efficient enough to remove the weeds before planting in the new seeds, you will be rewarded with a luscious lawn with good quality grass.

Sowing grass seed How Long After Weed Killer Can I Plant Grass Seed
Sowing grass seed – Copyright Kenneth Allen and licensed for reuse under this Creative Commons Licence.

Tips to Consider Before Planting the Seed

  • There is an herbicide called atrazine which can also be used for killing weeds. However, it is very deadly for grass; therefore, it should be avoided.
  • The type of grass that you are going to grow in your lawn also matters. You need to know the exact type of grass in order to select the type of herbicide that you can use to kill the weeds in your lawn. The chemical composition of the different herbicides can completely prevent the growth of the grass.
  • Overwatering of the soil can also prevent the growth of good quality grass.
  • You should also keep your pets and children away from the soil when you have sprinkled any form of herbicide on the lawn. You must also prevent watering of the lawn during this time because herbicide runoff can cause harm to everything around the runoff including the productive and fertile soil.
  • An analysis of the topsoil is also necessary for you to choose the type of grass that you would grow and the type of herbicide to be used in your soil. You will require an herbicide that will not contaminate the topsoil and will allow the growth of grass in the future.

Reference Link

You can view the following YouTube videos in order to know more about this subject:


We hope that this article was helpful and we could clear some of your doubts regarding replanting after the weeds have been cleaned out. However, there are a number of different options to choose from.

There is a set of herbicides that attack only a certain type of weed and does not affect any other form of growth. Before buying any type of herbicide, you need to make sure that the herbicide does not suck out all the nutrients from the soil.

This might not only harm the newly planted seeds, but also decrease the nutrient percentage of the soil. This can lead to your lawn becoming barren and unsupportive of any form of vegetation.

Hence, you should be very careful while buying the herbicide or the grass because a small mistake can result in the contamination of the topsoil and removal of essential nutrients that could help the growth of any species of grass.

Amazon is a great source of buying herbicides or weed killers and they provide an array of products for you to select from. Once you have understood the concept of planting, and analysis of topsoil and weed killing from this article, you can head over to Amazon to buy herbicides for your property.

We wish you a happy gardening journey and achieving a lawn that you can be proud of!