Sumo Gardener

When Should You Apply Weed And Feed Before Rain?

Weed and feed is a particularly common product known to lawn owners. Instead of having to use herbicide and apply fertilizer separately, the weed and feed chemical product does both at the same time. Ideally, this will improve your lawn’s ability to retain water and nutrients.

With healthy grass, your lawn won’t be easily invaded by bad weeds. In turn, this will reduce the need to use the same amount of weed and feed in the long run.

However, should you use weed and feed before the rain? Here, we’ll discuss the relationship between rain and this lawn chemical product.


When-to-Apply-Weed-and-Feed before rain

Understanding Weed and Feed

Simply put, weed and feed works by mixing broadleaf herbicide with a water soluble fertilizer. Some weed and feed products will have different nutrient ratios, but they all have a large amount of nitrogen to accelerate top growth.

Likewise, the herbicide that is combined with the fertilizer contains chemicals such as mecoprop and dicamba. This herbicide mix ensures that broadleaf weeds are quickly eliminated without harming any of the lawn grass.

To get sufficient nutrients from the weed and feed, your lawn needs moisture. The moisture helps the fertilizer break down so that nutrients such as phosphorus and nitrogen can go deep into the soil and reach the established plant roots.

However, your lawn shouldn’t receive too much moisture, hence, you shouldn’t apply weed and feed before the rain. The water will wash away the chemical.

Knowing the Effects of Weed and Feed

One of the main reasons why some people do not use synthetic lawn products such as weed and feed is the negative impact of the chemical on the environment. If you apply weed and feed right before rainfall, the runoff can easily travel to waterways such as streams and lakes.

Once this happens, algae blooms can occur in these areas and cover the water with dead vegetation. In turn, animals living in these waters will have a drastically reduced supply of oxygen.



Our Rating


Lesco Weed and Feed St Augustine Grass 17-0-7

Lesco St Augustine Grass Weed and Feed 17-0-7

Excellent for St Augustine Grass

Weed & Feed Turf Fertilizer Crabgrass Pre-emergent 18-0-4

Lesco Fertilizer plus Herbicide Crabgrass Pre-Emergent 18-0-4

Good for preventing crabgrass

Weed & Feed Turf Fertilizer 18-0-9

Lesco Weed and Feed Turf Fertilizer 18-0-9

Great for all grasses. For stronger lawns

Reading the Guidelines

If you do intend to use weed and feed before rainfall arrives, you should check the packaging. Usually, it will indicate that applying the lawn product one day or two days before receiving moisture is totally okay. 

Thus, you can still apply weed and feed a couple of days before the forecasted arrival of rain.

Here is a video showing how to apply weed and feed:

The exception to this is when the local weather forecast predicts heavy rain that can cause floods. A weed and feed fertilizer will likely have nitrogen components with a slow-release property. In other words, the nitrogen can stay for a relatively long amount of time on your lawn as it tries to get soaked into the soil.

With enough moisture from either irrigation or rainfall, the nitrogen will be immediately released into your lawn. However, flooding can wash away the slow-release nitrogen components and lead to wasted lawn products.

Some people think that applying more than the recommended amount is a good solution for the occurrence of floods. In reality, it is a totally not good idea.

Even though this won't have drastic effects on your lawn, the extra amount of weed and feed will negatively affect the waterways. Instead of wasting more of the product, just follow the instructions and apply it two days before rainfall.

Applying it After the Rain

Should you apply weed and feed before rain?

If you are just a day or even 12 hours away from rainfall, you should just wait for it to arrive before you apply the weed and feed. Once the grass blades are dry, go and check if the soil still has sufficient moisture.

The typical fertilizer contains a nutrient ratio of 20-0-10. Thus, every 1,000 square feet of your lawn should have at least three to four pounds of the product. However, this should only be done when the winds aren’t harsh and if the local temperature does not exceed 90 degrees Fahrenheit.

As you can see, applying weed and feed requires the right timing. If you want to use it before rainfall arrives, you have to do it at least a day before. Otherwise, you risk not only wasting weed and feed but also harming the environment.

The chemical runoff will reach lakes, rivers, and streams and result in a reduced oxygen levels for fish and other aquatic animals that need it. Furthermore, you have to read the guidelines and apply only the right amount of weed and feed.

We hope that this quick guide helped you learn about the effects of using weed and feed before rainfall occurs. If you have any queries, feel free to gives us a comment.

Can you apply weed and feed before rain?

About the Author Ann Katelyn

I'm Ann Katelyn, Creator and Chief Author of Sumo Gardener. Since I was a child I've always been fascinated with plants and gardens, and as an adult this has developed into my most loved hobby. I have dedicated most of my life to gardening and started Sumo Gardener as a way to express my knowledge about gardening with the hope of helping other people's gardens thrive.

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