Can You Use Preen On Mulch?

Can You Use Preen on Mulch

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Weeds are a year-round pest for gardens. You want to ensure that your lovely lilies or vegetable garden has a strong line of defense against thistles and weeds. If you already use mulch, can you use Preen on the mulch as a stronger defense against weeds? 

Applying Preen onto mulch adds an extra layer of protection to the soil and roots of your plants against weeds. As a pre-emergent herbicide, preen granules attack weed seedlings before they sprout. It is recommended to sprinkle Preen over the soil every three months for optimal defense against creeping thistles and thick knotweeds. 

Gardening is a fulfilling endeavor that can make your home feel vibrant with bursting lilies, roses, and lilacs. There’s also nothing more satisfying than being able to hand-pick ripe tomatoes and zucchinis to bring to the table for you and your family.

Weeds, however, are a year-round pest that requires constant vigilance. Keep reading to learn more about how adding Preen to mulch helps keep your garden weed-free.

How does Preen Work? 

Preen is a wonderful weed preventer that creates a barrier on the top layer of soil. 

Combined with mulch, it is a prime defense against weeds because it targets weed seedlings and dries them out before they sprout. 

While Preen is effective, it’s not enough to sprinkle it only once. Professionals recommend adding Preen atop your mulch every three months for maximum guaranteed prevention. 

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Does Preen work well with mulch?

Yes! Together, preen and mulch significantly impact the prevention of weeds. 


Mulch is an important part of keeping your plants healthy. The nutritious layer provides a rich ecosystem below the earth that keeps the soil cool. It also helps to lock in moisture and breaks down crucial organic matter vital for the roots. 

There are two main types of mulch used for gardening: rubber and organic. Professionals recommend organic mulch over the rubber to prevent chemical leakage as the mulch breaks down. 

Organic mulch includes wood chips, pine needles, cedar chips, pine, and hardwood chips and better contributes to the soil’s nutrition. 

What is Preen Made of? 

People want to ensure that their products are safe, clean, and natural. Luckily, Preen is 100% corn gluten, a protein of corn endosperm made largely of zinc and glutelin. 

How to use Preen with mulch? 

Applying Preen over mulch is relatively easy. Sprinkle your preferred brand of Preen (any kind from your local store will work) over the mulch. 

Spread one ounce of Preen over 10 square feet of your garden. As a rule of thumb, the granules should be placed relative to a quarter inch. 

Potential Risks 

Preen and other herbicides attack vegetable and flower seedlings, such as beans, carrot seeds, and weed seedlings. 

To prevent unintentional harm to your plants, apply Preen after the stem of the plants has grown about three inches. The plant’s maturity ensures it is strong enough to withstand the weeding-out process. 

If you already have weeds growing beneath the soil, applying Preen will not stop the weeds from growing, especially if they are of the henbit or bittercress breed. 

Preen can be very dangerous for marine life. To prevent environmental harm, dispose of preen containers directly into trash containers.

Additional Advantages

While some people prefer cultivation over preening, hours can be saved by sprinkling a few granules onto the mulch. 

Preen is safe for use for over 200 established shrubs, trees, flowers, and vegetables. Additionally, preen helps stop excessive nitrogen fertilizer, which typically results in an overabundance of leaves at the cost of flowers. 

What should you not use Preen on? 

Preen should not be placed on a naked soil bed if you have already sown vegetable or flower seedlings into the ground. Wait until the plants have grown 2 to 3 inches tall. 

There are some species of plants that are incompatible with Preen. Check the label on the back of your preen package to ensure it is safe to use with your plants. 

Preen is safe for ornamental grasses and ground covers, though it should not be used on lawns. Additionally, while Preen is safe for garden use, be careful not to expose children or pets to open Preen where they could touch or ingest it. 

Can Preen be used on ground cover? 


Keep the 2-to-3-inch rule in mind, and do not apply Preen to bare, wet soil. Known as “ground-hugging plants,” ground covers are an alternative grass. They are typically small, low-maintenance plants that reach about three feet tall and provide erosion control. 

Many popular ground cover plants include monkey grass and lilyturf, Algerian ivy, Asiatic jasmine, beach morning glory, creeping juniper, and liriope. 

Do I apply Preen before or after mulch? 

Preen should be applied after the mulch, followed by immediately watering it so that the Preen can seep into the mulch. For vegetable gardens, use organic Preen for safer digestion. 

Can you use Preen on pavers?

Technically, yes, you can use Preen on pavers. But remember, the purpose of Preen is to prevent weeds from sprouting. 

If you’ve found weeds sprouting between the cracks of your concrete decor, applying Preen will not help. In this case, you can try alternative options to get rid of the weeds, such as:

  • Using a butane torch (be careful 
  • Use vinegar: vinegar is an acetic acid that will draw out the moisture of the weeds and kill them. It is natural and fast. 
  • Pour boiling water on the weeds.

Does Preen work in rock beds?

Yes, preen works on rock beds. Rock beds can be particularly tiring and require constant replacing, moving, and cleaning of rock mulch. 

Applying preen can help keep weed maintenance to a minimum. 

What does Preen kill?

As a pre-emergence herbicide, Preen can kill several harsh weeds, such as crabgrass, foxtail, cheatgrass, purslane, and spotted spurge. 

Remember, it kills all seedlings indiscriminately. So, ensure your desired plants are 3 inches strong before applying Preen. 

How to use Preen?

Sprinkling anything onto the rich soil is always satisfying. You can watch a full demonstration of how to apply Preen.

Can you plant a garden after putting down Preen? 

Yes, you can plant seeds after applying Preen. However, before using the Preen, you must first gut your garden of all weed roots. 

Wait at least twenty-four hours before sowing flower or vegetable seeds into the soil, as they may not germinate and could be killed along with weed seedlings. As an additional tip, rake the ground after pulling the weeds to prevent weed clippings from surviving. 

Is Preen worth it? 

Yes, absolutely. 

Preen is unique because it is harsh enough to kill weed seedlings but is not harmful to the rest of your flower and vegetable seeds. 

It has natural, specialized formulas that stop the germination of weeds before they have the chance to become those pesky, hairy vines. 

Should I Buy Preen 

Remember, the removal of weeds is a continual process. But if you want less hassle and maintenance, buy yourself a small package of Preen. 

It generally does not fail, and customers are consistently happy with their weed-free yards. Preen will help easily maintain a weed-free yard with plants that will grow longer and more robust. 


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