How to keep caterpillars off plants naturally, without using chemicals. Natural insect repellents for garden plants.
My newly planted spinach, kale, cauliflower and broccoli leaves have been developing gaping holes. I’m an organic gardener, so I avoid using any chemicals or toxic sprays on my plants, but this means my garden is left wide open to your not-so-friendly neighbourhood bugs and pests.
These are some of methods I’ve found to help keep very hungry caterpillars away…
Before we get started in learning how to deter caterpillars from the garden naturally – if you like what you’re seeing, subscribe to my email newsletter at the bottom of the page to keep up to date on the latest recipes, DIYs, gardening and health tips I share!!
Natural Ways to Keep Caterpillars Away
Before we start, it’s important you identify specifically which caterpillars you’re dealing with, because some methods will get rid of certain types of caterpillars, but will be ineffective against others. The methods below cover some of the most common types of caterpillars.
Cutworms are found below the surface of the soil and will eat through seedlings’ stems during the night. To help prevent this, grab some plastic cups or toilet paper rolls and cut them into 5 cm strips. Place them around young seedlings to protect them from these pests.
Another option is to use sterile soil to start your seedlings, as this will prevent any pests that live through the winter eating your baby plants.
These guys target tomato plants and will strip them of their leaves in less than a day. Picking them off by hand – while wearing gardening gloves – works well at getting rid of these caterpillars. After you’ve picked them off, drop the hornworms into a jar that contains soapy water, which will kill them. Alternatively, you can use your shoe to squish them.
A kinder option is to dump any caterpillars you find into the garbage bin.
Swallowtail Butterfly Caterpillars
You’ll often find them on dill, parsley, fennel, coriander, carrot and parsnip. Do not kill them. It’s advised that you handpick these caterpillars off the plant and move them to a patch of Queen Anne’s lace (wild carrot, it’s a wildflower herb) or to another location away from the garden.
Alternatively, planting extra dill, parsley, and fennel for the butterflies is another way to keep these little guys away and ensure there’s enough to go around.
There are a few different types; black swallowtail caterpillar (source), orchard swallowtail butterfly caterpillar (source), Blue Mountain swallowtail caterpillar (source), and the spicebush swallowtail caterpillar (source).
Cabbage Moth Caterpillars
Covering your garden and plants with translucent fabric – which allows light to still pass through – or using polypropylene row covers can help protect cabbages, mustard plants, swede, or rapeseed from falling prey to cabbage moths and other pests.
To make your own row covers; stick hoops into the ground and cover them with either perforated plastic or fabric sheeting. These materials should let in both sun and air but also serve as a barrier for most bugs. Weigh down row covers on one end using bricks, wood planks, or other heavy materials – preventing it from blowing open.
Check Plants Frequently for Eggs
Sweep up and remove all of the fallen leaves and debris around your plants each autumn. This will help keep the caterpillar populations under control – in case there are any eggs hidden amongst all the debris. Throughout the growing season, check the leaves on the plants for caterpillar eggs, paying particular attention to the underside of leaves.
When you find any eggs, pinch off the egg or snip off the leaf and throw it in the garbage.
Encourage Birds and Wildlife to your Garden
Beneficial insects to foster that prey on caterpillars include chalcid, brachonid and ichneumon wasps – these aren’t the kinds of wasps that sting people. Grow plants such as carrots and parsley to attract them, and leave them to flower. Encourage caterpillar-eating birds into your area by bringing in a birdbath or a bird feeder, and leave an area of your garden to grow a little wild, which provides cover and nesting areas.
Heavily Intercrop your Garden
Intercropping or companion planting involves growing plants singly or together in a given area to repel insects, fight disease, or promote the growth of another plant. It’s a technique many gardeners have used for generations.
Creating effective crop combinations helps repel insects by using plants’ natural fragrance, oils, compounds and colours to keep pests away. Try some of the combinations below and keep a record of what works.
Growing mugwort, sage, thyme, rosemary, and/or peppermint around affected plants may help deter caterpillars, as these herbs produce a strong scent so will help disguise these foods, meaning butterflies/caterpillars may look elsewhere for food.
Here is a list I found from Harvest to Table that shares companion plantings specifically targeted at pests. There are also companion plantings you can create in your garden to attract beneficial insects.
Neem Oil Pesticide
Neem oil and bacterial sprays work really well as natural pesticides, helping to keep caterpillars and other insects away from garden plants. When sourcing neem oil, look for 100% cold pressed neem oil with Azadirachtin. This is essential. It must contain Azadirachtin in order to be effective against bugs. It’s the component of the neem tree that helps disrupt the lifecycle of chewing and sucking insects.
Always test spray your plants first, and then wait 48 hours to see if there’s any damage. Do NOT spray an entire garden bed, just one or two leaves, check it, and if everything looks okay, you can spray it again.
How to Make a Neem Oil Spray for Plants
To make the neem oil spray:
- In a spray bottle filled with 2 litres water, add 1 tbsp neem oil, 1/2 tsp each peppermint oil and rosemary oil, and 1 tsp natural soap to help the oils disperse in the water. The essential oils will help to mask the natural scents of the plants you’ll be spraying, to prevent insects smelling their fragrance and laying eggs on the plants. Shake well to combine.
- Test spray a couple of leaves first, let sit for 48 hours, then check the plant to see if it’s okay. If all looks good, you can continue spraying the plants.
- Spray your plants in the morning, before bee activity is heavy. This spray shouldn’t harm them, it’s more out of respect to the bees, so you’re not spraying them directly while they’re pollinating.
- You want the leaves to be dripping wet with this spray, and make sure to coat both the front and back of the leaves. Spray the soil as well, as the bugs most often will crawl up onto the plants from the ground.
- For preventative maintenance, spray down the garden with this spray every 1-2 weeks, just to help keep the bugs under control. However, if you do have an infestation, you want to spray more often, every 3-5 days, for around 2-3 weeks or until you see the infestation go away.
See here for more information on how to grow a garden organically at home.
As always, this is not personal medical advice and we recommend that you talk with your doctor before trying or using any new products. I am not a doctor. All opinions expressed are my own personal thoughts and feelings of the products mentioned. Check with your doctor or health practitioner if you are uncertain about trying out any of the products, recipes or tips mentioned in this post.
How do you keep pests away from the garden? Share below.
Lots of love,
How to Keep Caterpillars Out of the Garden. (Updated: March 29, 2019). WikiHow. Retrieved from https://www.wikihow.com/Keep-Caterpillars-Out-of-the-Garden
Albert, Steve. Insect-Deterrent Plants For The Vegetable Garden. Harvest To Table. Retrieved from https://harvesttotable.com/insect-deterrent_plants/
Green, Jenny. (Updated: December 14, 2018). How to Get Rid of Caterpillars Without Pesticides on Plants. SFGate. Retrieved from https://homeguides.sfgate.com/rid-caterpillars-pesticides-plants-29475.html
CaliKim29 Garden & Home DIY. (June 26, 2020). Organic Pest Control Spray for Your Vegetable Garden for Aphids & Chewing Insects. YouTube. Retrieved from https://youtu.be/ZS2xfjeiBgs