Do Chrysanthemums Really Keep Pests Away From Your Garden? We Asked Pros

Chrysanthemums, often called hardy mums or garden mums, are daisy-like, many-petalled flowers that bloom from late summer through autumn. They’re a popular choice for autumn containers and decor, and many nurseries and farm stores sell them as a seasonal item. In fact, they’re so ubiquitous that some gardeners find mums to be overrated. Though they’re often grown as annuals and discarded, these perennial flowers are a colorful and long-blooming presence in the late-season flower bed.

But mums also have utility beyond their beauty: their distinctive “flower shop” scent is due to compounds that can help deter insect pests. We spoke with some garden experts about whether mums really work for repelling pests, and they all agreed they can be an effective part of pest prevention efforts.

Do Chrysanthemums Really Repel Pests?

Some gardeners think chrysanthemums repel pests due to their scent, but this is only partly true. Rhonda Kaiser, a master gardener and landscape designer, says their real pest-repelling power comes from natural chemicals known as pyrethrins.

Another garden expert, Annette Hird, agrees that mums are believed to repel pests due to the presence of pyrethrins. Though she thinks it may be debatable whether most garden mums repel pests on their own, she confirms that pyrethrins extracted from plants do make excellent insect repellents.

The important thing to keep in mind is that there is only one chrysanthemum variety that contains pyrethrin in amounts significant enough to be an effective pesticide. That variety is Chrysanthemum cinerariifolium, also known as Tanacetum cinerariifolium, Pyrethrum daisy, or Dalmatian daisy. It has white daisy-like petals and prominent yellow centers that have a rounded shape.

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Why Chrysanthemums Work

The mums known as Dalmatian daisy or pyrethrum daisy are effective insect deterrents because they contain large amounts of naturally occurring pyrethrin. Kaiser says that while planting these mums in the garden may be an effective deterrent, pyrethrins are most effective when concentrated into sprays and other products.

Kaiser says that one advantage of pyrethrin products is that these compounds break down quickly in the environment, so they are a more environmentally friendly alternative than most synthetic pesticides.

Though pyrethrin compounds are often extracted from pyrethrum daisies and used to make commercial pesticides, these are not always organic formulas. You can, however, make your own organic pesticides from mums.

Pests Chrysanthemums Are Best For

The mums known as Dalmatian daisy can be an effective pest control option against insect pests. Pyrethrin in an insecticide spray works to kill a wide range of destructive insects, including aphids, thrips, mealybugs, whiteflies, and many more, as well as nuisance insects like ticks, cockroaches, silverfish, and ants.

Insects that are repelled by strong-smelling plants like catnip and lavender, such as mosquitoes, are also deterred by all chrysanthemums (not just Dalmatian daisies), because of their pungent (though pleasant to most humans) scent.

How to Make Chrysanthemums Work As Pest Deterrents

Though making an insecticide spray is the most effective use of certain mum varieties to kill insects, the strong scent of all mums can be an effective insect deterrent in the garden when they are planted strategically.

• Choose the correct chrysanthemum variety. The one known to contain pyrethrum in ample amounts to help deter insects is the pyrethrum daisy, or Dalmatian daisy, aka Chrysanthemum cinerariifolium. Other chrysanthemum varieties may be effective deterrents against some insects, such as mosquitoes.
• Plant near areas where you want to deter pests. This may be by your garden shed, patio, or outdoor seating area. Consider mums also as companion plants near your vegetable garden.
• Give your plants proper growing conditions. Mums of any variety need well-drained, rich soil and plenty of sun to bloom and thrive. Hird says that morning sun is desirable, and these plants benefit from some shade in the afternoon to protect them from the scorching sun.
• Prune the plant to encourage branching and blooms. Hird says that pruning young perennial mum plants is essential to promote bushy growth. Deadheading also helps encourage more flowers, and the flowers are where the plant’s insect-repelling properties are concentrated.