Are Grubs Good for Soil?

What Are Grubs?

Grubs are the larval form of beetles.

Why Grubs Love Garden Soil

Grubs like cool, moist places filled with decomposing matter.

This means they'll feel right at home in your garden soil or your compost bin. You're likely to find grubs in both places if your soil and compost are healthy.

What Do Grubs Do?

They grub around, obviously.

Grubs fill a role similar to earthworms here in the desert Southwest. Since we don't have worms, this niche is partially filled by grubs, ants, and all manner of other macro decomposers.

Grubs help to break down organic matter in soils and compost, and aerate them while doing it. This improves soil quality, drainage, moisture retention, and nutrient availability.

Your plants will love the hard work grubs do for their soil!

What Do Grubs Eat?

Grubs eat mostly organic and decomposing material in soil.

Do Grubs Damage Plant Roots?

Native grubs in Tucson do not damage plant roots (despite what you've heard.)

Invasive grub species, however, such as Japanese beetles may damage plant roots. We don't have these in the Sonoran desert, though, and none of our native grub species eat plant roots.

While some beetles such as palo verde beetles have a symbiotic relationship with host trees, they don't kill them and pose no risk to mature palo verdes.

Primarily macro decomposers, grubs would much rather consume decaying organic matter such as leaves, mulches, sticks, rotting wood, compost, and chop + drop.

What Problems Can Grubs Cause in Garden Soil

In some regions and climates, larval beetle grubs can be detrimental to plant roots. It's worth reiterating that none of the species native to Tucson will kill your plants.

If you're in a different region, you may notice some detrimental effects from them on root growth, however.

I think this is a completely overblown threat to plant roots, however.

You're not going to be able to dig them all up, nor would any pesticide lend a net positive affect to your garden. Screw that!

Pesticide companies have been demonizing grubs for years, but truthfully they just want you to buy their crappy poison and destroy your ecosystem. There are far fewer damaging grub species than these companies want you to believe, and they do far less damage than most people think.

Ultimately, if you do have a grub species which chows down on plant roots - that means you've got a team of soil-building critters to help you make great dirt. Sure, maybe you'll lose a couple plants to them - but resilient healthy plants won't fall prey to a couple grubs. And healthy, balanced ecosystems won't be overrun by any 1 type of "pest" anyway.

If you've got a grub inundation, that's just a sign that your ecosystem isn't balanced. Killing pests you don't like or applying nasty pesticides WILL NOT help you get your ecosystem in balance, though. Quite the opposite!

Many gardeners have a tendency to undervalue decomposers and soil-builders, and over-demonize anything which might eat organic matter. Start by balancing your mindset, and ecosystem balance will follow.

What to Do About Grubs in Your Garden

Embrace them! They're here to help your soil, not to harm your plants.

They may seem creepy-scary, but that's only because there aren't enough people advocating for them.

Pesticide companies are incentivized to market straw-men to you and over-demonize a whole cast of bugs. Insects are one of the most critical pieces of an organic garden, though!

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Do a quick Google search of whether grubs damage your garden, and you'll notice all the top results are from pesticide companies. It's no coincidence that they are paid to sell you "solutions" to things which aren't a problem in the first place. Pest companies are not neutral players so I'd advise caution before accepting most of what they have to say.

If you choose to grow outdoors organically, you have to take the time to learn about your local characters and the important roles they play in a regenerative garden ecosystem.

If you don't like insects and aren't willing to learn more about them and embrace them, you should grow hydroponically indoors in a sterile environment.

Next time you see some jumbo grubbers while digging in yer' dirt, rejoice that they've showed up as an indicator of healthy soil! And remember that they're here to help you on your quest so be nice to grubs.

Happy gardening, y'all!