How to Prevent Cutworms in the Garden

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Cutworms can wreck havoc on your garden in just one evening. Learn what a cutworm looks like and how to prevent cutworms from destroying your garden.

What is a Cutworm?

First, let’s look at what a cutworm is. A cutworm is the larvae of a brown or gray moth that overwinters in the soil. The moth lays eggs on plants and garden debris. The eggs hatch and the worm buries itself in the soil.

The worms can be any number of colors, but the majority of them are brown or gray. They can have spots or stripes on their bodies.

Cutworms can be mistaken for grubs as their appearance is very similar. If you touch a cutworm, it will curl up into a “C” shape. They range from about 1 to 2 inches long.

cutworm on a leaf
A cutworm on a leaf. Cutworms can do lots of damage to your garden in just one night.

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Cutworms tend to do the most damage early in the spring. I’ve had the most trouble with them on broccoli, cauliflower, cabbage, and brussels sprouts, but they can damage many other crops as well. They seem to love newly transplanted seedlings.

A tell-tale sign that a cutworm has been in your garden is that your plants are cut off at the base. Sometimes you will even find the top laying nearby.

The reason cutworms are so destructive is they cut the plants off at the base, either above the ground or below the ground. They basically circle the plant and chew on the stem causing the top to be lopped off. This is usually enough to kill the plant.

You won’t see cutworms at work during they day. They feed at night, though you may come across a few as you are digging holes for your transplants.

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Ways to Prevent Cutworms in the Garden

While nothing is 100 percent effective there are ways to deal with cutworms in your garden. I’m going to list the methods from what I’ve personally found to be most effective to least effective.

I recommend trying a few of these methods together if cutworms are a problem in your garden.

Make Plant Collars

The most effective treatment I’ve found to deal with cutworms is prevention. And the method I’ve been most successful with is using toilet paper rolls to make plant collars for your transplants.

We save toilet paper rolls all year long for this very purpose. The easiest way to use a toilet paper roll is to split it up the side and place it around your plant. Bury it at least an inch in the ground. (Remember cutworms can cut off your plants below ground too!)

The cutworm collar works to prevent the cutworm from accessing the stem of your plant. Be sure that the ends of the toilet paper tube meet once you’ve planted your plant.

Place a Stick Beside Your Plant

prevent cutworms by placing sticks beside the stems of your plants
Cutworms can be prevented from eating your plants by placing sticks beside the stems.

I’ve had decent luck placing a stick beside my plants too. You can use sticks from your yard, popsicle sticks, or even old pens and pencils.

You do have to ensure that the stick is touching the stem of the plant both above and below the ground. This keeps the cutworm from being able to circle the plant by providing extra girth. The hard stick also makes it more difficult for the cutworm to find the stem and chew through it.

Occasionally I have still had a cutworm manage to get to a plant using this method. I think it’s because the stick shifted slightly allowing him room to get to the stem.

Diatomaceous Earth (DE)

Diatomaceous earth (DE) can also be used to deter cutworms. DE is the fossilized skeletons of tiny aquatic organisms. It comes in a powdered form that you can sprinkle around your plants.

The sharp edges cut up worms as they crawl over the DE and it also works soak up moisture from the worms and dry them out. It remains effective as long as the product stays dry. But it must be reapplied after a rain.

DE is considered organic. However, I always encourage you to do your own research before using any product, organic or not, in your garden.

The biggest issue with using DE is after an overnight rainfall. The rain will wash the DE away and the cutworms will still come hunting your vegetables. They can still do quite a bit of damage during the night before you have a chance to reapply the DE.

Bacillus Thuringiensis (BT)

Bacillus Thuringiensis (BT) is often recommended for the prevention of cutworms. BT is a soil-borne, naturally occurring bacteria that has been used since the 1950’s. It is considered safe for organic gardens too.

While BT is useful for many other worms and caterpillars, it must be ingested by the worm for it to work. This means you have to apply it directly to the stems of the plants you want to protect.

It takes 2 to 3 days for BT to kill the worm once eaten. In the meantime, the cutworms can still do a lot of damage. I recommend skipping BT for cutworms.

Other Methods of Cutworm Prevention

There are some other things that can be done to help prevent cutworms from destroying your garden. However these methods offer various degrees of protection.

Hand-Picking Cutworms

Hand-picking the cutworms is often recommended. While I am all for using this method for other pests, I don’t want to rely solely on hand-picking to ensure I get all the cutworms.

First, handpicking the cutworms needs to be done at night. You won’t find them out and about during the day. So remembering to go out each night to hunt for cutworms by flashlight really isn’t my idea of a good time.

Also, you can easily miss cutworms because they are often the color of the soil and they can be hiding under any mulch you may have put down. Miss one worm, and you can lose quite a few plants overnight.

Plant Sunflowers as a Trap Crop

Some sources suggest planting sunflowers as a trap crop. The problem with this method is that sunflowers are a warm season flower that should be planted after your last frost.

This will do nothing to deter the cutworms early in the spring when they tend to do the most damage to cool-season crops like broccoli, cauliflower, and cabbage. And these are the vegetables that seem to get hit by cutworms the most in my garden.

Keep a 3 Foot Border Around Your Garden

Some experts recommend keeping a 3 foot border of bare dirt around your garden. While this may be practical for farmers and gardeners with lots acreage, it isn’t practical for most backyard gardens. I also wouldn’t want to deal with a 3 foot muddy mess every time it rains.

The Best Method of Cutworm Prevention

cutworm collar around a broccoli plant
I use a combination of a toilet paper roll and a popsicle stick to prevent cutworms from destroying my plants.

After much trial and error, I have found the best method for cutworm prevention, at least in my garden.

For cool-season crops, I use both a stick and the cutworm collar together. The year I started doing both is the first year I didn’t lose any of my cauliflower and broccoli to the little buggers. Unfortunately, I did lose a few plants to a very late cold snap!

For plants such as peas and beans, where it is difficult if not impossible to place sticks and collars around them, I use a sprinkling of diatomaceous earth around the plants as soon as they emerge from the ground.

Combined, these methods have prevented any cutworm damage in my garden this year. Your results may vary so I recommend trying several methods to see what works best for you.

If you have had cutworms and been successful at controlling them in your garden, I would love to hear your methods. Drop a comment below and let me know what has worked in your garden.

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