GARDEN TIME with DOUG – Mulch and Preen, a Great Gardening Combination


Everyone knows what mulch is. But, how many of you are familiar with the product PREEN?


PREEN is a pre-emergent weed preventer that creates a weed-prevention barrier in the top layer of soil and mulch. Preen will NOT kill weeds that have already sprouted.


A resounding YES! If you are like me then you get frustrated and tired of seeing weeds growing in your landscape beds. Bottom line – I am only going to do so much weed pulling by hand.

There is no question that mulch is the first line of defense against weeds. It is now mid-March and this is a perfect time to be applying some fresh mulch to the beds. Keep in mind that you only need two or three inches of mulch at any one time. Any more than three inches and you are only wasting your money.

To help you with this mulching task we have:

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  • RAKE –  Get the rake out and start raking these landscape beds. Clean out these garden beds in order to start with a nice, clean slate.
  • WET PAPER –  Before applying mulch consider laying down some wet newspaper over the beds and around plants. The newspaper will eventually decompose but first will create a natural weed barrier and work hand-in-hand with mulch and Preen in preventing weed growth.
  • MULCH –  Next step is to apply a fresh layer of mulch.  Mulch is a protective material placed over the soil.  It helps retain moisture, keeps soil and plant roots cooler, will break down into the valuable organic matter over time and will deter some weeds while making your garden beds look nice and tidy.  There are many types of mulch.  It is a personal preference as to whether you choose hardwood, pine, cedar, pine needles, or wood chips.  It doesn’t matter because they all serve the same purposes.
  • PREEN –  You sprinkle Preen on top of the mulch in order to create this weed barrier.  As with any gardening product, it’s important to read the product label and follow instructions.  Most gardeners apply their first application of Preen right now.  Unfortunately, there are some winter weeds already sprouting and growing such as henbit, bittercress, and others that Preen will not kill.  But, more weeds are coming.  A second application of Preen should be applied there months later in order to help prevent later sprouting weeds from developing.


 Once Preen is applied I suggest that you don’t do too much walking or cultivating in the beds because you can “break” up this barrier which will then allow weeds to sprout and grow.


24 thoughts on “GARDEN TIME with DOUG – Mulch and Preen, a Great Gardening Combination”

  1. Thank you — LOVING these ‘calendar reminders’ of what the heck we’re supposed to do in the garden. By the time I usually think about Preen — weeds are up and we’re fully into Spring. Please keep doing this! 🙂 HUGELY helpful.

  2. What is better to lay over the dirt before the mulch is laid down… plastic or “weed felt” (more open weave)?

    • Lyn,
      Good Morning. Definitely use a weed fabric and not any plastic. The fabric will allow moisture through and at the same time keep weeds from penetrating through. Doug

  3. I see it says Preen will not harm shallow rooted perenials or bulbs, but specifically, what about hibiscus? We cut ours off at ground level in the fall, and they have come back for a few years. Right now, they have not sprouted up yet, but we are trying to prevent the weeding this year.

    • Harry,
      Good Morning.
      You are safe. Preen is safe to use around our hardy, herbaceous perennials, such as the hibiscus. Preen keeps “seeds” from germinating and growing. The soil is still a little chilly for our hardy hibiscus to start growing. Thank you for taking the time to send us your gardening question. Doug

  4. I have several established perennial beds with mixed spring, summer and fall plants. Should I apply preen BEFORE they start coming up (right now in early spring – blank slate with no plants yet emerging) or wait until plants start to emerge and have grown a few inches and then apply AROUND the plants? Thank you!

    • Kathy,
      Good Afternoon. Preen should not affect your perennials from coming and up and growing. Preen can be used in many garden beds such as around herbs, vegetables, and perennials. Once you put Preen down then you want to try not to walk through these gardens. Walking can break the barrier that Preen creates. Doug

    • John,
      Thank you for this question. Actually, putting Preen down first is more effective in keeping weeds from growing then it is to put Preen on top of the mulch. Or, if you really want the best protection then you may want to think of doing both underneath and on top. Doug

  5. I did not put Preen down….lots of weeds now, early June in North East Zone 6. Can I still Preen after I weed well for new growth? What do you suggest?

    • Lynn,
      Weeds are constantly growing, flowering, and dropping seeds. So, yes, Preen cam help reduce / eliminate future weeds from germinating and growing. Good luck, Doug

  6. I live in Savannah Ga and weeds start sprouting early. We rarely have a hard, prolonged frost. I never know when to start applying Preen

    • Sherry,
      Good Morning. We both know that Savannah is in a warmer climate than here in Richmond. With this said then I would think about putting Preen down in late January or around the first of February. Preen stays active for around three months. So, for you in Savannah earlier the better chance of keeping the early sprouting weeds from germinating. Then I would consider putting down a second application of Preen in two to three months. Good luck. I love Savannah. Doug

    • Pam,
      Good Morning.
      I think you will need to purchase the products separately. I am not aware of any product that you can buy that has mulch and Preen already together. Doug

    • Thank you.
      I had no idea that Preen has wood chips. Up to this point we have not carried the wood chips in our inventory. Thank you for this information. Doug

  7. THe pumpkins that I planted from seed died after I applied preen and mulch, they weren’t up very far when I applied the preen. Now I have looked for a cause to the loss of the plants and can’t see any guidelines on the preen sheet for pumpkins. Do you think it could have caused the loss of the plants?

    • Pat,
      Good Afternoon.
      Sorry to read about you losing your pumpkin plants. To my knowledge Preen should not be the culprit since you mention that the pumpkins had already started growing. But, I can’t say 100%. I just don’t know what would have caused all your pumpkin plants to die. I hope that somehow you can solve this mystery. Doug

  8. We just planted 2 beautiful David Austin rose gardens as well as some hydrangeas and vinca flowers. My husband put Preen down before putting down about 2 inches of good black mulch and then he sprinkled Preen on top of the mulch also. Is that too much Preen? Will it be harmful? Is Preen ok for shrub roses? Really want to know because we have 60 shrub roses and they were expensive so don’t want them to die! Please reply.

    • Linda,
      Good Morning.
      You are good with using Preen under as well as on top of the mulch. Preen is safe to use in and around shrubs. Preen is keeping weed seeds from germinating and not hurting established shrubs or trees. Thank you for this message. Take care, Doug

  9. I use Preen in the fall, in the early spring and before planting seeds. How does it keep weeds from growing but my flower seeds still germinate??

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