Is It Safe to Use Pre-Emergent Weed Preventers Around Bulbs?

Is it safe to use pre-emergent herbicides (such as crabgrass preventer) around my established bulb beds? -Helen

The short answer is “sometimes,” because in gardening a simple question doesn’t always have a simple answer! Products that are labeled as “weed preventers” are usually pre-emergent herbicides, which work by stopping seeds from germinating, so it stands to reason that they shouldn’t affect established bulbs (especially dormant bulbs underground). However, that’s not always the case, as a product labeled “weed preventer” may have any number of active ingredients that affect weeds, seeds, and garden plants in different ways. Every product should be evaluated separately to make sure it’s safe.

Corn Gluten: The Organic Choice

Corn gluten meal is a popular organic choice for preventing weeds. Corn naturally produces a substance that suppresses the germination of competing seeds. In addition to its weed preventing properties, corn gluten is high in nitrogen and adds some organic matter to the soil – nature’s own “weed and feed!”

Sold under brand names such as Preen Organic Weed Preventer, corn gluten meal is considered safe for use around bulbs, shrubs, trees, and ornamental plants. In addition, it’s far less toxic than chemical herbicides.

Chemical Herbicides: Check the Label

As for commercial chemical weed preventers, you really need to read the label. Some are safe around all bulbs, some are safe only if you apply before the bulbs sprout, and others aren’t safe at all. Before applying, read the label (and do a little research) to make sure the product is safe.

Examples of common products include:

In general, I would use corn gluten meal (or just pull the weeds by hand), simply because I don’t want those other chemicals in my yard. Many chemical herbicides are known to be directly toxic to our health, not to mention deadly to the environment. I’d also focus on enriching the soil and strengthening the desirable plants, because unhealthy gardens are prime targets for pesky weeds.

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5 Comments on “Is It Safe to Use Pre-Emergent Weed Preventers Around Bulbs?”

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  • Official Comment:

    Thomas Boni Says:
    October 2nd, 2018 at 9:26 am

    Hi, Frances,
    We haven’t covered that topic yet, but you might try this resource from our friends at the Cherokee County Cooperative Extension:
    Let us know how it works for you!

  • Frances Helms Says:
    October 2nd, 2018 at 7:51 am

    My yard is infested with wild wisteria – impossible to pull up…..HOW can I destroy it? I’ve read there are herbicides which can be painted on the individual stems/leaves without harming sterilizing the surrounding soil. What do you suggest? Thanks.

  • Edward Says:
    August 31st, 2018 at 5:08 pm

    Enjoy your monthly newsletter. Have gained much practical and useful tips in many areas.

  • Donisha Says:
    June 20th, 2017 at 7:01 am

    Can I use Preen over caladium tubers that have not sprouted yet?

  • Jeff Erbs Says:
    May 31st, 2017 at 12:21 pm

    Preen is not listed for use around lily bulbs!

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Is It Safe to Use Pre-Emergent Weed Preventers Around Bulbs?