DOUG’S GARDENING BLOG – Preen and Mulch is Double Trouble for Weeds


Weeds, like some of our early blooming ornamental trees and shrubs, are ahead of schedule and are actively growing. But, more varieties of weeds are getting ready to sprout. Now is the time to apply PREEN and MULCH to your landscape garden beds.

Everyone knows mulch and what it does to our landscape – adding a fresh look, helping to keep the ground shaded, cooler, and moist longer. Mulch is considered the first line of defense against weed growth.



Our 3 cu. ft. bag HARDWOOD MULCH is on sale from March 10 – 18

Four 3 cubic foot bags for only $14.40

(regularly $4.59 a bag)

Now, let’s talk about PREEN. How many of you are familiar with Preen? You need to be. It’s a great product. Preen is a weed preventer. When applied to garden beds it creates a barrier and stops weeds before they can even start growing.

Preen and mulch work in tandem as a one/two punch against weed growth. And, this combination will help to reduce or eliminate any need to spray herbicides for weed control in the future because you stopped weed growth in their tracks. To me, this combination of Preen and mulch is very eco-friendly for our environment – especially when you can greatly reduce or eliminate spraying herbicides. Our bees and other beneficial insects will thank you.

Here are the steps involved in applying PREEN and MULCH to your existing garden beds:

  1. Pull all actively growing weeds (and, we have some now).
  2. Sprinkle Preen evenly on your garden beds
  3. Water the product into the soil
  4. Add 1” to 2” of mulch

How simple is this!!!! Now you are ready to sit back and enjoy a weed-free garden.

Like this blog? Read more of Doug’s posts here

22 thoughts on “DOUG’S GARDENING BLOG – Preen and Mulch is Double Trouble for Weeds”

  1. I am trying to dig up the onions that popping up in my flowerbeds, but of course I can’t get all of it out. Will PREEM kill them?

    • Mary,
      No, unfortunately Preen will not control wild onions or wild garlic from growing. These pesky weeds grow from an underground bulbs – as you already know. Digging up those white bulbs is the best remedy for control. You can also resort to a spray herbicide such as Kleen Up, Weed B Gon, or Pulverize. Doug

    • Helen,
      Absolutely, many customers will sprinkle Preen on top of the mulch in order to continue weed germination. So, by all means, do it and then enjoy a weed free garden. Doug

    • Leslie,
      Bonide makes a great product for controlling chickweed. It is called CHICKWEED CLOVER & OXALLIS KILLER. Being a liquid herbicide then you want to keep pets off the lawn until it dries. Once it dries then it should be safe. The only true “organic” control of chickweed that I can come up with is using WHITE VINEGAR and spray the entire weed thoroughly. Doug

  2. Doug,
    I need a product that will control weeds in the cracks between the bricks on my brick/sand patio. Will preen do this?
    Thank you!

    • Preem will keep weed seeds from germinating but will not kill any existing growing weeds. If this describes your situation then Preen could be a good preventative to weed growth. If not, and weeds are already growing then a good, quality liquid herbicide would work well – such as Pulverize. Let me know if you have any further questions. Doug

  3. How does Pulverize compare to Round up and Weed B Gon in relation to the environmental impact?

    • Patricia,
      Good Morning. And, good question.
      As you probably are aware about the health issues surrounding Round Up and glysophate. Pulverize active ingredient is Iron Hedta and is much more environmentally friendly and non-toxic. It works. Doug

  4. I have large thick beds of lirope I want to get rid of. What’s the best and safest way to do so? I want to replant the area with perennials.

    • Sarah,
      Good Morning. The first step I would suggest is to spend some time and try to dig up as much of this liriope as possible. Because liriope is dormant now and not putting out new growth, this makes any herbicides, such as Round Up or Pulverize, ineffective. Doug

  5. I’m wondering if Preen is effective as a pre emergent for lawn as well as garden? I only have a small area of both and hoped that you could point me to a product that would work for both. Thanks!

    • Mary,
      Good Morning. And, a good question. Unfortunately, Preen is not made to use on lawns. What you need is a lawn pre-emergent product. We have it available. Now is the time to get it down. Doug

  6. Does it help to put compost down in the garden bed prior to the mulch and preen? anything else we should be applying for a healthy garden of plants?

    • Rich,
      Great question. My quick answer is YES. Anything that you can do to enrich the soil and add organic matter will get your plants off to a great start this spring. Doug

  7. I have rocks in the area around our fire pit and a flower bed where I put pots of outdoor plants. The weeds come up through the rocks. Will it help to put Preen on top of the rocks after removing the existing weeds?

    • Deborah,
      Preen could possibly help. But, Preen will not be able to get under the rock and weeds could germinate from under the stone / away from the Preen product. So, I don’t think it will be 100%. It’s too bad that you can not install a weed fabric under the stone. This would certainly help keep weeds in check. Doug

  8. Can you please suggest something to get rid of mugwort? I have been trying to get rid of them from my plant beds for 10 years. Tried weed block sheet, preen,, even newspaper, pulling them out and digging out the roots. Thanks in advance.

  9. Please consider adding a disclaimer about the toxicity of Preen (trifluralin), and any other biocidal chemicals you promote. Your customers should be aware of possible adverse impacts to their local environment and personal health, and the actions they can take to minimize risk. For Preen, these include:
    *Toxic to fish, amphibians, and other aquatic life at low concentrations.* Do not use if you live in the vicinity of streams, ponds or wetlands—stormwater will carry Preen far from the application area.
    *Possible human carcinogen and androgen blocker (i.e., might mess with testosterone).* Avoid direct dermal contact, inhalation, and ingestion (obviously!)
    *Kills many native beneficial plant species that support honey bees, butterflies, and other pollinators.* This effect is difficult to avoid, as Preen will spread beyond the application area no matter what. Consider adopting a garden/lawn design that minimizes biocide use and incorporates native plants.

  10. Is it okay to use Preen and mulch for that matter, in a vegetable garden?

    Also is it good to use around blueberry bushes?

    • Joel,
      Good Morning.
      Good question.
      Preen and mulch can be used around vegetables and small fruits. The two together is a one / two punch against the growth of unwanted weeds. HOWEVER – Preen is NOT an organic product. So, if you want to stay organic than you need to control weed growth with other methods. The one good thing about Preen is that it can help eliminate the use of any liquid herbicides.

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