The Preen range of products is very popular and used in hundreds of thousands of gardens around the globe.
Its pre-emergent herbicides are effective but how safe are they around certain plants?
For instance, can Preen be used around hydrangeas?
That is what we are here to answer today.
So let’s not waste any more time, let’s get started!
Can Preen Be Used Around Hydrangeas?
The only Preen product that is safe to use around hydrangeas is Preen Vegetable Garden Organic Weed Preventer. The active ingredient in this is 100% corn gluten meal. Each of its other products are not classed as safe to use near hydrangeas and could cause issues such as stunted growth and wilted foliage.
It is worth noting that Preen is a brand created by the Lebanon Seaboard Corporation, as opposed to a single product.
Preen’s catalog of products is mainly pre-emergent chemical herbicides, ie you use them before weeds rear their ugly head, rather than using them to kill weeds once you see them.
The active ingredient in Preen products is Trifluralin (also known as Treflan).
If you take a quick google of Trifluralin, you will see that it is quite widely used. The Wiki page on Trifluralin tells you that 14 million pounds (6,400 tonnes) was used in the USA in 2001.
But Trifluralin (I have to keep checking the spelling of that every time I type it), is banned in the European Union as it is highly toxic to aquatic life.
I say this because if you live on a property with a pond or any kind of water nearby this is very important to know.
But anyway, let’s get on with the rest of the article and look at some of the Preen products on the market and if they can be used around hydrangeas…
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PRODUCT 1: Preen Vegetable Garden Organic Weed Preventer – Safe
Preen Vegetable Garden Organic Weed Preventer is safe to use around hydrangeas,
Its active ingredient is 100% corn gluten meal. As an additional bonus corn meal gluten is also a fertilizer with a ratio of 10-1-1.
And Preen states on its website “Children and pets can play in the area immediately after application”.
Preen Vegetable Garden Organic Weed Preventer should be applied every four weeks around already established hydrangeas.
Just sprinkle it evenly over the soil, rake gently in and then water the soil to activate it. Once this is done, do not water for at least two days.
Full details of Preen Vegetable Garden Organic Weed Preventer can be found on the Preen website.
VERDICT: ✔ Safe to use around hydrangeas
PRODUCT 2: Preen Garden Weed Preventer – Not Safe
Preen produces three slight variations of this. None of them are safe to use around hydrangeas as they could cause issues, notably stunting their growth.
Whereas the active ingredient in Preen Vegetable Garden Organic Weed Preventer is 100% corn gluten, for these three products it is different:
- Preen Garden Weed Preventer: 1.47% Trifluralin
- Preen Garden Weed Preventer Plus Plant Food: 1.47% Trifluralin
- Preen Garden Weed Preventer Plus Ant, Flea and Tick Control: 0.27% herbicide Dithiopyr, 0.11% insecticide Bifenthrin
Each of these products is classified as safe to use around a large number of established plants. If you are thinking about buying some for your garden your best option is to check the labels below
- Preen Garden Weed Preventer
- Preen Garden Weed Preventer Plus Plant Food
- Preen Garden Weed Preventer Plus Ant, Flea and Tick Control
The application process when using any of these three products is essentially the same.
- Manually remove any existing weeds.
- Distribute the product over the ground.
- Rake it into the soil.
- Water the area where it has been applied to activate.
As the name suggests the version with plant food acts as a ‘weed and feed’, preventing the emergence of weeds and also contains an all-purpose fertilizer to help your plants grow.
The version with ant, flea and tick control also controls a number of other insects as well. These include weevils, crickets, earwigs and grasshoppers.
Full details of any of these products can be found on the Preen website.
VERDICT: 🗙 Not safe to use around hydrangeas
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PRODUCT 3: Preen Extended Control Weed Preventer – Not Safe
Preen Extended Control Weed Preventer is also not safe to use around hydrangeas. It is one of the few plants you want to keep the substance at least 2 to 3 feet away from.
As the name suggests Preen Extended Control keeps weeds away for longer.
Whereas the products we have discussed so far keep weeds at bay for one to four months, Preen Extended Control keeps them away for up to six months.
It can be applied up to twice a year around existing plants. The first application can be made at any time during the growing season, the second should be made two to six months later.
The application process is exactly the same as all the other Preen products. Manually remove existing weeds, sprinkle the product evenly over the soil, rake gently to integrate it into the soil and then water to activate it.
The active ingredients of Preen Extended Control are 1.5% Trifluralin and 0.375% Isoxaben. It is the Isoxaben that lengthens the active time of the substance.
Full details of Preen Extended Control Weed Preventer can be found on the Preen website.
VERDICT: 🗙 Not safe to use around hydrangeas
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Hope this article gives you a better idea of what you should not use Preen on.
You can use Preen around many existing shrubs but, with the exception of its Vegetable Garden Organic Weed Preventer product, it shouldn’t be used around hydrangeas.
For a quick rundown of what is what when it comes to its products this Which Preen is Right For Me page on the company’s website is handy.
You should also remember that each one of Preen’s herbicides, again with the exception of its Vegetable Garden Organic Weed Preventer product, is extremely toxic to aquatic life.
It is clearly stated on the labels that it shouldn’t be allowed to run off into storm drains, drainage ditches, gutters or surface waters.
Also remember Preen is very different from Round-up and some other non-selective herbicides that kill weeds on contact.
Preen is a pre-emergent and should be used to stop weeds before they appear.
2 thoughts on “Can Preen Be Used Around Hydrangeas? (Solved)”
Wow! I love this article!!! I have been doing residential landscaping for years and have mostly used Preen to prevent killing hydrangeas as I was told it was safe. When I looked at the labels, I have never found Hydrangeas listed as a vulnerable plant for the product. So, I used it. To make matters worse, I even went so far as to pay a lot more money for a product called Snapshot because my supplier said it was the cadillac of pre emergents. Come to find out it’s almost the same thing as most of the Preen products.
Thank you for posting this!!! Looks like it’s corn meal gluten products for these types of beds for now on!!!!
Thank you Joshua, appreciate your kind comments!