Nothing tastes better than fruits, vegetables, and herbs grown and harvested from a home garden. Not only can you pick them when they are at peak ripeness to get optimal flavor, but you can also have the pleasure of knowing that no harsh chemicals were used on them. With commercial pesticide use affecting nearly all of our food supply, many people have started to wonder if it is even possible to grow great food naturally. How do you control all of those detrimental garden pests that are as excited to eat that beautiful garden as you are?
Fortunately, natural gardening is not only possible, it is arguably the very best way to grow food. This Ultimate Guide to Tackling Garden Pests Naturally will walk you through all the steps needed to have a successful garden. With a little knowledge on natural pest control methods and some great resources, you will be well on your way to a healthy, productive garden.
Steps to Natural Pest Control
1. Create an Environment That Will Promote Healthy Plants
If you are looking for the most important piece of advice about natural pest control, it may be this: Do what is necessary to grow the healthiest possible plants. Healthy plants are simply more resistant to pests. There are many ways to create this environment, but it all starts with great soil. Mikl Brawner, natural gardening expert and owner of Harlequin’s Gardens says, “Strong and healthy plants have few pests, and strong and healthy plants come from strong and healthy soil.” Here are some ways you can create a great environment to grow those strong, healthy plants.
- Add nutrients to the soil through organic compost and clean mulch
- Make sure that your soil has the right PH and is the right soil type for the crops you are planning to grow
- Ensure good drainage by using raised beds, garden boxes, or various types of drains
- Fertilize, if needed, using a natural fertilizer like clean manure or kelp seaweed powder
- Grow many different kinds of plants and rotate them each year
- Pick varieties of plants that are most resistant to the pests in your area
- Choose plants that will thrive in your Hardiness Zone
- Ensure proper amounts of sunlight when deciding garden and plant placement
- Give your plants the right amount of water
If you consider and implement all of the above mentioned things, you will be giving your plants the best possible chance for survival against garden pests. If you notice that one of your plants is weak or sickly and is being attacked by pests, it may be necessary to tear out the plant before it attracts even more. By maintaining healthy soil and healthy plants, your garden has an immediate advantage.
Companion plants are those that have natural properties that help each other by either increasing yields or repelling pests. As an example, members of the onion family tend to help many different plants because they repel pests with their strong smell. With some companion plants, it is unknown exactly why it works, but experience has shown that it does. Here are a few of the potential companionships that will benefit your garden.
- Celery: Plant with cabbage and broccoli to repel white moths
- Catnip: Plant with squash, cucumbers, and pumpkins to repel squash bugs and aphids
- Radishes: Plant with cucumbers to repel cucumber beetle
- Borage: Plant with tomatoes, cabbage, and strawberries to repel hornworms and cabbage moths
- Rosemary: Plant with carrots and cabbage to repel carrot flies and cabbage moths
- Nasturtium: Plant with tomatoes, cabbage, melon, and squash to repel squash bugs and whiteflies
- Tansy: Plant with raspberries and roses to repel Japanese beetles
- Basil: Plant with tomatoes to enhance their flavor and repel whiteflies, spider mites, and aphids
- Dill: Plant with squash, cabbage, and other cole plants to repel squash bugs and cabbage worms
- Marigolds: Plant with tomatoes to repel hornworms
- Lavender: Plant with lettuce, spinach, and other leafy crops to repel whiteflies and aphids
- Parsley: Plant with asparagus to repel asparagus beetles
- Onions and Garlic: Repel many bugs and will benefit almost all other garden plants
3. Attract Helpful Garden Predators
One of the very best ways to take care of garden pests naturally is to encourage beneficial bugs and animals in your garden. These are creatures that don’t do damage and are actually predatory toward detrimental pests that destroy your crops. Instead of using harmful chemicals, you can rely on the natural food chain to take care of pests. There are two main ways to get beneficial insects to your garden: you can attract them or you can purchase them. Before spending money to buy or attract them, identify the pests that you are having trouble with and learn which insects or animals will help get rid of them. Here are some of the good bugs that you want in your garden and how to best attract them.
Ladybugs (AKA Lady Beetles)
Pests Controlled: Aphids, mites, white flies, scale, other insect eggs
Attracted By: Dill, fennel, yarrow, cilantro, caraway, scented geraniums, and cosmos
Pests Controlled: Aphids, caterpillars, mealybugs, thrips, whiteflies, scales
Attracted By: Coreopsis, cosmos, sweet alyssum
Pests Controlled: Stink bugs, aphids, caterpillars, scale
Attracted By: Marigolds, lavender, white clover, fennel, dill, rosemary
Pests Controlled: Fruit flies, moths, grasshoppers, caterpillars, wasps, aphids, leafhoppers
Attracted By: Shrubbery where they can lay eggs, roses, raspberries, tall grass
Pests Controlled: spider mites, other mites, thrips
Attracted By: pollen, humidity, azaleas, fruit trees
Pests Controlled: Aphids, caterpillars, scale, eggs of beetles and moths
Attracted By: Marigolds, goldenrod
Pests Controlled: Slugs, snails, cutworms, aphids, cabbage maggots, Colorado potato beetles
Attracted By: ground cover, mulch, stones, logs, clovers, amaranth
Pests Controlled: Beetles, caterpillars, shield bugs, Japanese beetle, squash bugs, codling moths, earwigs
Attracted By: Queen Anne’s lace, carrots, cilantro, dill, cucumber
Pests Controlled: All types of insects, mosquitoes, moths, beetles, wasps
Attracted By: Tall plants, mulch (grass clippings, leaves)
Pests Controlled: Aphids, thrips, scale insects, caterpillars
Attracted By: Oregano, chives, sweet alyssum
True Bugs (Assassin Bug, Spined Soldier Bug, Pirate bug)
Pests Controlled: flies, hornworms, Mexican bean beetle, leafhoppers, aphids
Attracted By: Queen Anne’s lace, daisies, fennel, dill, mulch
Other Beneficial Garden Creatures
Aside from predatory bugs that feast on other bugs, there are many other creatures that can be beneficial in your garden. Encourage animals like frogs, toads, birds, newts, and even hedgehogs to frequent your garden. Do this by providing moisture, hiding places, and areas of shade. If you keep backyard chickens or ducks, your garden will likely benefit from them as well because they decrease the overall insect population. These friendly creatures will eat lots of those damaging pests and save you from having to try harsher methods of pest control.
4. Employ Mechanical Pest Control Methods
Mechanical pest control is the control of pests using physical means like barriers, fences, or physical removal. It can also include things like changing the condition of an area or changing the temperature. When pests start attacking your garden despite your best efforts at prevention, it is always best to solve the problem through the gentlest means possible. Professional gardener, Brawner, again says, “If damage levels are too high, use the least toxic, least invasive method that will support your plants.” This is why mechanical pest control is such a great place to start.
Use Row Covers
Row covers are a physical way of keeping garden pests away from the plants. Garden fabric used for covers comes in different weights and allows light, air, and water to get to the plants. Row covers can float above the plants supported by metal hoops or lay directly on the plants if it is light-weight. For pest control purposes, row covers should be set up right after planting and removed (at least a few hours per day) when blossoms appear so that the plants can be pollinated. You can buy or make row covers.
It may seem tedious, but handpicking is one of the best ways to target specific pests with little impact on the rest of the garden. Handpicking works best on larger insects like beetles, caterpillars, squash bugs, etc. Each morning, make a quick sweep of the garden, picking off any pesky critters you may find. Pick the bugs or shake them off into a jar of water with a few squirts of liquid dish soap. When you find adult bugs, you may also need to check for eggs. Most eggs are laid on the underside of leaves and can be many different colors including white, orange, and dark brown. Gently dislodge them with your fingernail or crush them. Handpicking is particularly valuable early in the season to get rid of the first generation of pests and prevent them from laying eggs.
Diatomaceous Earth (DE)
DE is actually the fossilized remains of tiny aquatic organisms. It has microscopic sharp edges that will cut the exoskeletons of many insects, causing them to dry out and die. Diatomaceous Earth is non-toxic and safe to use, although be careful not to breathe it in. Sprinkle it around plants to eliminate or repel pests.
Depending on the size of pest you need to keep out, fencing can be a good barrier. A garden fence can be relatively short for things like rabbits and voles, but will need to be much taller if you are dealing with deer. Other barriers for soft-bodied creatures like slugs could be as simple as spreading crushed eggshells or diatomaceous earth around plants. These are sharp, and many crawling pests won’t cross them. Slugs and snails can also be deterred by copper rings or copper tape placed around individual plants.
Traps are not likely to be a stand-alone solution to pest problems, but they can be excellent at helping you monitor your garden to see what pests are present and approximately how many there are. Yellow sticky fly traps, apple maggot traps, and codling moth traps are just a few of the traps used in gardens. You can also build your own snail and slug beer traps to keep them away from your leafy greens.
6. Experiment with Natural Pesticides
A pesticide is nothing more than a substance that is used for killing insects or other organisms that are detrimental to plants or animals. We tend to think of pesticides as harsh chemicals, but there are several natural pesticides that can be used with little impact on the environment or other life in the garden. Below are several types of pesticides that are preferred in natural gardens. While pyrethrum, rotenone, and others are derived from natural plants, their detrimental effects on beneficial bugs and other garden creatures make them less appealing to natural gardeners, so they will not be included here.
DIY Organic Sprays
There are many things found in your kitchen that can be made into a spray to repel and irritate garden pests. These sprays can also smother and kill their eggs and larvae, which is why they are included in this section on natural pesticides. These substances are inexpensive, safe, and will not harm beneficial bugs, birds, or other creatures. They include garlic, onion, mint, and hot peppers. When soap or oil are added to these mixes, the spray is able to coat the leaves of the plants and will last longer and be more effective. There are many different recipes and formulations for these sprays, so you can experiment with what works best for you and your plants. You can spray it on a small section first to see how your plants tolerate your specific formulation.
Garlic-Mint Garden Spray
1-2 full heads of Garlic (depending how strong you want it)
1 small onion (optional)
2 cups of Fresh Mint or ~15 drops of peppermint essential oil
1 gallon of Water
2 TB liquid dishwashing soap (biodegradable)
Directions: Combine garlic, onion, and mint in a food processor. Bring the liquified mixture to a boil. Let the mixture steep for 12-24 hours. Strain the mixture using cheesecloth or a fine mesh strainer. Put the ingredients in an old gallon milk jug and fill to the top with water. Then add the dish soap. Lastly, pour some into a spray bottle and store the rest in the fridge. The mixture will last approximately 1 week. Spray on garden plants before pests are causing problems to repel them. Apply spray 1-2 times per week in the evenings.
Hot Pepper Garden Spray
7-10 hot peppers
1 TB vegetable oil
5-10 cloves of garlic (optional)
1 TB liquid dishwashing soap (biodegradable)
1 gallon of water
Directions: Blend ingredients in the blender with about 3 cups of the total water. Blend thoroughly. Let it stand for a couple of hours and blend again. Strain using cheesecloth or other fine strainer. Add the remaining water, and put the mixture into a spray bottle. Store extra in fridge for 1-2 weeks. Caution: Wear gloves when handling hot peppers and be careful not to touch your eyes. Spray on plants in the evening so that it will not burn the plants.
Insecticidal soap is mostly used against soft-bodied pests (aphids, spider mites, etc) as a dessicant. It is a biodegradable soap that when sprayed directly on the pest will damage cell membranes, causing the cells to eventually collapse, killing the pest. It is one of the least toxic pesticides, and it will not harm other beneficial bugs.
This is a highly refined oil that you can mix with water and spray on plants as a pest control method. It works by coating the insect, causing it to suffocate. It must be sprayed directly on pests and will not work after it has dried. Horticultural oil is safe to use around mammals and other animals, but is toxic to fish. Horticultural oil does not discriminate between good and bad bugs, so it should be used cautiously.
This is an oil that comes from the seeds of the neem tree in southern Africa. It blocks an insect’s ability to progress through the life cycle. It can take several days for it to kill the pest, but in the meantime, it also acts as an appetite suppressant, which bodes well for your garden. Evidence shows that neem spray is relatively safe and does not affect beneficials bugs, but may be moderately toxic to fish, so use with caution.
5. Use Biological Pest Control
One step up from mechanical control is biological control. Wikipedia defines biological pest control as “a method of controlling pests such as insects, mites, weeds, and plant diseases using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also involves an active human management role.” Basically, this means that you use a pest’s natural enemies (bacteria, fungi, viruses, etc.) to control their population size.
Bacillus thuringiensis (Bt)
Bt is a bacterium that is naturally found in the soil that paralyzes the digestive tract of various caterpillars. It is a great way of controlling pests like cabbage worms, hornworms, Colorado potato beetles, gypsy moths, and corn borers. While it works great for these pests, it can also be harmful to certain types of butterflies like monarchs and swallowtails, so be cautious not to overspray your garden.
Milky spore is a control measure for Japanese beetles. It can be applied to lawns where adult beetles lay their eggs. The grubs come to the surface and ingest the bacteria. The milky spores multiply rapidly and kill the grubs.
Nematodes are wormlike organisms. Some species cause problems in gardens, but the ones specifically sold for insect control feed on wireworms, borers, beetles, and root maggots. These beneficial nematodes definitely have a place in a natural garden.
By I, Luc Viatour, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=3440776
16 Common Garden Pests and How to Control Them
There are thousands of different species of garden pests that may attack your fruits, vegetables, trees, and ornamentals. With proper identification and a good natural treatment plan, you can keep your plants healthy and get rid of the pests. There are extensive lists of garden pests available, but we want to spotlight 16 of the most common and most damaging garden pests.
Description: Small, pear shaped, soft bodied insect with long legs and antenna; Often found in dense clusters under leaves or around new growth; Can be many different colors (light green, pink, black, etc.)
Plants Affected: Various species are found on nearly EVERY type of garden plant
Damage Caused: A few aphids usually will not hurt a plant, but a large infestation can cause the leaves to turn yellow and fall off. Aphids also secrete a sweet liquid called honeydew that attracts ants and can cause sooty mildew.
Control Methods: Beneficial bugs (ladybugs, lacewings, parasitic wasps), neem oil, grow strong scented plants (chives, garlic, mint), floating row covers, hot pepper spray, insecticidal soap
Description: Various insects are classified as leafminers, but one of the most common is the larvae of the black fly. Insects lay their eggs on the underside of leaves, and the larvae is what does the damage.
Plants Affected: Spinach, lettuce, tomatoes, beets, etc.
Damage Caused: The larvae eats into leaves and creates tunnels between the layers of a leaf. These tunnels appear as trails inside the leaf and are usually lighter in color.
Control Methods: Remove eggs found on underside of leaves, encourage parasitic wasps, use row covers
Description: Very small, light yellow insects with fringed wings that consume the sap of plants; Signs of thrips include black shiny specks (excrement), deformed growth, and stippling of plants.
Plants Affected: Asparagus, cabbage, onions, peas, potatoes, cotton, and many other fruits and vegetables
Damage Caused: Feeding can create abnormal growth of plant tissue called galls. They may prevent leaves or buds from opening. Thrips are highly destructive in large numbers.
Control Methods: Row covers, insecticidal soap, Encourage parasitic wasps
Description: Over 7,000 different species of insects are in the scale family. They are soft-bodied insects that have a protective shell that is usually rounded. They attach to the plant to suck the juices. Scale normally appear as small bumps on the stems and can vary in shape and color. Mealybugs are part of the scale family.
Plants Affected: Affects many agricultural food crops, trees, shrubs, and other plants
Damage Caused: Causes leaves to turn yellow; The plant may wilt and look sickly. In rare cases, it may kill the plant.
Control Methods: Gently scrape it off with a fingernail, prune branches that are affected, encourage ladybugs, soldier beetles, and parasitic wasps, carefully wash plants with soapy water or rubbing alcohol (test a small area first), neem oil
Description: These mites look like very small spiders with 8 legs and webbing around them. They prefer warm, dry weather.
Plants Affected: Beans, tomatoes, cucumbers, squash, melons, peppers, berries, etc.
Damage Caused: Causes yellow or white stippled leaves. They can stunt the plant and create visible webbing. Leaves may turn yellow and die.
Control Methods: Insecticidal soap, weed control, floating row covers
Description: Very small insects (1/16”) with powdery white wings
Plants Affected: Tomatoes, cucumbers, lettuce
Damage Caused: Whiteflies extract plant juices causing the leaves to wilt and turn yellow and sickly. They also produce honeydew that promotes the growth of sooty black fungus.
Control Methods: Yellow sticky traps, attract parasitic wasps and ladybugs, remove infested leaves
Description: Colorful beetles found in the Midwest and Eastern United States; Approximately ¼” – ½” long with a metallic bluish-green head and shiny copper wing covers
Plants Affected: Roses, beans, grapes, raspberries, and many more
Damage Caused: Japanese beetles skeletonize leaves so that only the veins remain; May defoliate the entire plant.
Control Methods: Handpick, floating row covers, neem oil, soap sprays, milky spore
Mexican Bean Beetles
Description: Usually about ¼” long with 16 black spots on its yellow body. They look like a yellow ladybug.
Plants Affected: Beans, peas, beets, squash, tomatoes
Damage Caused: They skeletonize leaves so that only the veins remain; Can cause death to the plant
Control Methods: Handpick, row covers, parasitic wasps, insecticidal soap, neem oil
Colorado Potato Beetles
Description: Yellow or orange in color with black stripes on the wings. Typically about ¼” long.
Plants Affected: Potatoes, eggplants, peppers, tomatoes
Damage Caused: Skeletonize leaves until only the veins remain
Control Methods: Row covers, handpick, crush eggs, insecticidal soap, neem oil
Description: Usually around ⅝” long and dark brown or gray; Shield shaped with a hard shell and 2 pairs of wings.
Plants Affected: Pumpkins, zucchini, winter squash, cucumbers, etc.
Damage Caused: Squash bugs suck sap from leaves and will damage the fruit; They inject a toxic substance that will turn the leaves brown and brittle and eventually kill the plant.
Control Methods: Neem oil, diatomaceous earth, row covers, inspect underside of leaves weekly, handpick adults and carefully scrape off eggs, soap sprays
Description: Small, shield shaped bugs that have bright red, orange, or yellow markings
Plants Affected: Broccoli, cauliflower, kale, brussels sprouts
Damage Caused: Harlequin bugs suck plant juices from leaves and stems causing yellow or white blotches on the leaves; Can also cause wilting and plant death.
Control Methods: Row covers, handpick, weed (especially mustard plants and pigweed), encourage damsel bugs and pirate bugs
Description: Small green inchworms that destroy vegetables in the cabbage family; Adult form is a gray moth that lays eggs underneath leaves; Causes very similar damage to cabbage worms.
Plants Affected: Broccoli, cabbage, kale, cauliflower
Damage Caused: They chew up leaves, create holes in broccoli and cabbage heads, and leave black droppings known as frass on vegetables.
Control Methods: Handpick worms, crush eggs, row covers, bacillus thuringiensis, encourage parasitic wasps
Description: Typically around 1” long and gray or black; Hide just below ground during the day, and curl up in a “C” shape; Found throughout North America and thrive in weedy areas.
Plants Affected: Particularly damaging to plants in the cabbage family; Also peppers, tomatoes, peas, and beans
Damage Caused: Cutworms damage plants in early spring by cutting the stem off at ground level.
Control Methods: Use cutworm collars around young plants, delay planting, bacillus thuringiensis, control weeds, handpick
Description: Bright green, fat caterpillars that can grow up to 3 inches long; Adult form is the sphinx moth that is grayish-brown with bright orange spots. It can have a 4-5 inch wingspan.
Plants Affected: Tomatoes, peppers, eggplants, potatoes
Damage Caused: Hornworms strip the leaves down to the stem, and can damage the exterior of the fruit causing scarring.
Control Methods: Handpick, till the soil, parasitic wasps
European Corn Borers
Description: Beige caterpillars that can grow up to about an inch long
Plants Affected: Corn, beans, tomatoes, peppers
Damage Caused: They bore into the leaves and stalks, leaving a hole that looks like it contains sawdust; Can weaken the stalk causing it to break.
Control Methods: Encourage ladybugs and lacewings, handpick, plant resistant varieties
Slugs and Snails
Description: Soft-bodied creatures (although snails have a hard outer shell) that eat many plants in the garden. They produce shiny, slime trails and are mostly found in moist, temperate climates throughout the United States. Slugs can be ½” – 5” long.
Plants Affected: Lettuce, spinach, tomatoes, and others
Damage Caused: They create irregular holes in leaves where they have been feeding.
Control Methods: Handpick after dusk or after rain; Use copper rings or copper tape; Weed and thin out plants to get rid of hiding spots; Make and use beer traps; Put a ring of rough material around plants (gravel, diatomaceous earth, or crushed eggshells), encourage frogs, toads, lizards, and birds.
Common Pests Based on Plant Type
Perhaps you aren’t sure where to start when identifying what kind of pest you are dealing with. It may be easier to search for common pests based on the plant you are growing. Here are the most common pests that affect these garden vegetables:
Asparagus: Asparagus beetle, aphids, cutworms
Beans: Mexican bean beetle, root-knot nematodes, bean weevils
Beets: Aphids, beet webworms, blister beetles, European corn borers, flea beetles, seed corn maggots, vegetable weevils
Broccoli: Cabbage aphids, cabbage maggots, cabbage loopers, cabbageworm, cutworm, harlequin bug, flea beetle
Brussels sprouts: Cabbage aphids, cabbage maggots, cabbage loopers, cabbageworm, cutworm, harlequin bug, flea beetle
Cabbage: Cabbage aphids, cabbage maggots, cabbage loopers, cabbageworm, cutworm, harlequin bug, flea beetle
Cauliflower: Cabbage aphids, cabbage maggots, cabbage loopers, cabbageworm, cutworm, harlequin bug, flea beetle
Carrots: Carrot rust fly, wireworms
Celery: Aphids, celery leaftiers, European corn borers, thrips
Corn: Corn earworm, European corn borer, seed corn maggots, corn sap beetles, corn root aphids, wireworms
Cucumber: Cucumber beetles, spider mites, melon aphids, squash bugs, squash vine borers, pickleworms, squash beetles, cutwoms, thrips, leafminers
Eggplant: Colorado potato beetles, eggplant lace bugs, flea beetles, grasshoppers, hornworms, potato tuber worms
Lettuce: Slugs, snails, leafminers, aphids, cabbage worms, cabbage loopers
Melons: Melon aphids, blister beetles, pickleworms, seed corn maggots, spider mites, cucumber beetles, squash vine borers, thrips
Onions: Onion thrips, vegetable weevils
Peas: Aphids, pea weevils, cowpea curculio
Peppers: Cutworms, pepper maggots, pepper weevils
Potatoes: Colorado potato beetles, flea beetles, aphids, wireworms
Pumpkins: Cucumber beetles, spider mites, melon aphids, squash bugs, squash vine borers, pickleworms, squash beetles, cutwoms, thrips, leafminers
Radishes: Blister beetles, flea beetles, harlequin bugs, turnip aphids, vegetable weevils
Spinach: Aphids, beet webworms, fall armyworms, flea beetles, grasshoppers, leafminers, vegetable weevils
Strawberries: Aphids, Japanese beetles, raspberry crown borers, rose scales, spider mites, stink bugs
Sweet potatoes: Wireworms
Tomatoes: Tomato fruitworm, potato aphid, stink bugs, hornworms, whitefly, spider mites
Winter Squash: Cucumber beetles, spider mites, melon aphids, squash bugs, squash vine borers, pickleworms, squash beetles, cutwoms, thrips, leafminers
Zucchini: Cucumber beetles, spider mites, melon aphids, squash bugs, squash vine borers, pickleworms, squash beetles, cutwoms, thrips, leafminers
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The Garden is Waiting…
Now you have all the information and help necessary to grow an amazing garden using natural pest control. When those pests come, as they surely will, you will be able to tackle them in environmentally friendly ways that you can feel confident about using. Remember, natural pest control starts with creating an environment for growing the healthiest possible plants, and then encourages companion planting, attracting beneficial predators, employing mechanical pest control, using biological control methods, and experimenting with natural pesticides. Following these steps will get you well on your way to enjoying the fruits of your labors.
Other Valuable Resources:
Smith, Edward C., “The Vegetable Gardener’s Bible,” Storey Publishing, 2009.