Does Dithiopyr Need To Be Watered In? [Explained]

does dithiopyr need to be watered in

One of the most common dithiopyr-based questions I get asked is whether or not dithiopyr needs to be watered in. The answer, unfortunately, is a little complicated. It depends on a bunch of factors, such as how much rainfall your area gets, and your soil type.

However, as a general rule of thumb, does dithiopyr need to be watered in? Yes, dithiopyr does need to be watered in with around 1/2 inch of water over the following 7 days.

In this article, I’ll go over the basics of watering in dithiopyr and give tips on how to do it correctly!

Watering In Dithiopyr

When it comes to watering in dithiopyr, there are two primary considerations: the amount of water and how long you need to keep applying it. Firstly, you should be sure to apply at least 1/2 inch of water over the following 7 days after application. This ensures that the active ingredient is absorbed into the soil for optimal effectiveness.

Secondly, you should make sure to water in dithiopyr at the same time of day each day. This helps ensure that the active ingredient is evenly distributed throughout the soil. When applying dithiopyr, it’s essential to make sure that the correct amount of water is used and applied over a consistent period of time.

Grow Your Yard Tip
Ideally, it would be best if you watered dithiopyr in right away. This goes for 2 EW and 40 WSB.

You’ve got a couple of options for watering in, and it’s entirely down to personal preference. You can time the application when it’s due to rain, but obviously, that will only work out sometimes, or you can sprinkle/water it in.

Personally, I prefer to time my dithiopyr application with the rain, call me old school, I like letting nature take its course!

It’s important to note that if you wait to water it in immediately and it hasn’t rained, it’s not the end of the world. The dithiopyr is still applied for when it does rain, but I wouldn’t wait too long before you water in, as weeds may have begun sprouting before you’ve activated the herbicide.

How Long Does Dithiopyr Last?

The other question I often get asked is how long does dithiopyr last? Generally speaking, applied dithiopyr should last around 4 months after “activation”. Depending on the season in which you apply, your results may vary significantly.

For example, if you apply during a wet season, then your dithiopyr might last up to 8 weeks; however, if you apply during a dry season then it might only last up to 4 weeks.

Dithiopyr doesn’t last as long as Prodiamine, however, dithiopyr acts as both a pre and post-emergent, which is a huge bonus.

How Much Water Do You Mix With Dithiopyr?

It’s important to mix the dithiopyr with the correct amount of water for optimal results. Generally speaking, you should mix 16 to 32 fluiz oz per acre. 

The dosage will be challenging to control if you’re using a hand sprayer, but if you use a broadcast spreader, I’d recommend using it to spray water on a quarter-acre or half-acre and measure how much water you’ve dispensed, from there you can figure out how much spray it’ll take to cover your entire yard.

Recommended Products

I won’t go into too much detail as I’m sure you’ve got your own favorite products, but I’ve been using Dimension 2EW for years now, and it’s always been great, especially when using it alongside prodiamine.

It’s pretty expensive but well worth the price tag. Make sure you always go for a liquid-based dithiopyr, the granules are not suitable.

Frequently Asked Questions:

Is dithiopyr a carcinogen?

No, dithiopyr is not considered to be a carcinogen. It does have the potential to cause skin and eye irritation if not handled properly, but it does not pose a cancer risk when used following its product label instructions.

The Environmental Protection Agency (EPA) has deemed it safe when used as directed.

What is the shelf life of dithiopyr?

The shelf life of dithiopyr is typically two to three years, so it does not need to be used immediately after purchase.

However, you should always check the expiration date on the label before using. Additionally, be sure to store your product in a cool and dry place away from direct sunlight for optimal results.


There you have it, dithiopyr does require watering in for optimal results. I’d recommend watering it in immediately or timing it for a good amount of rainfall.

Let me know how you get on in the comments below!

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