How to Keep Pests Out of Your Garden

We’ve all seen it happen. One day your crops are stunning, green, and thriving under the golden sun. Maybe even a couple tomatoes are close to harvest time. The next day you go out to bask in the glory of all your hard work, and your plants are decimated. Leaves chewed, some pulled up entirely, stems covered with little bugs —you can’t even see the green anymore! Nothing will ruin your day quite like it. Luckily, with a little proactive planning and execution, we can avoid this nightmare — or at least keep it at bay. 

Garden pests are a part of our garden ecosystem. In the best cases, they act as food for our friendly bugs and pollinators, but in the worst cases, they end up being the only sign of life left in our garden. Garden pest control isn’t easy and takes time to perfect, but it can be built into your gardening practice and become part of your cycle of tasks. If you start looking out for signs of pests early, you can also avoid the worst case scenarios by handling the issues sooner rather than later. 

Identifying Common Garden Pests

With some practice, you’ll be able to identify common garden pests like you identify the plants growing in your garden! While it may seem overwhelming at first, learning your friends and foes will help to keep track of the overall systemic health of your garden. 

Aphids

Aphids are one of the most common pests you’ll come across. While they can be extremely sneaky, keeping a close eye on your crops will help mitigate their damage! If you see any small white, black, or sometimes even green bugs all stuck together covering the stem of your plants, these are likely aphids. They are sucking bugs so they love especially juicy foliage and, left to their own devices, can stunt the growth of your crops and cause eventual death. They spread quickly, so as soon as you start seeing a few, take some action! 

In many cases, a strong stream of water can knock aphids off the plant, and they’ll have trouble getting back up. In more extreme cases, a regular application of neem oil can help to keep populations at bay. If you know aphids are a regular problem in your garden, you may consider interplanting, or companion planting, with beneficial plants that can either deter aphids or act as a decoy to attract them, saving your actual crop from being sucked to death. 

Colorado Potato Beetles

Colorado potato beetles are most often found on — you guessed it — potatoes! They can be found on other solanaceous plants like eggplants and tomatoes as well. If you haven’t seen them, but you’re wondering how your crop got defoliated overnight, maybe take a closer look. These invasive pests are extremely destructive and are best caught early due to their natural resistance to many pesticides. Luckily, they are highly recognizable in all of their stages.

Adult beetles, which you can spot by their orange, spotted prothorax and black stripes on their wing covers, will lay their eggs on the undersides of foliage. The ravenous larvae will spread from their hatching spot to eat the leaves of your crops. The eggs are oval and a bright, shiny orange. Adult females can lay many eggs over the course of several weeks. We recommend not only squishing the eggs when you find them, but handpicking the adults and dropping them in a bucket of soapy water as well. 

If the eggs have already started hatching, you’ll want to work quickly to collect the larvae, also squishing or dropping them into soapy water. The larvae are a deep orange color with two rows of black spots on either side of their squishy bodies. 

It’s best to start watching out for them as soon as your potatoes are popping out of the ground or soon after you transplant your other solanaceous plants. Hand-picking is one of the best proactive moves you can make to defend against these pests. 

Flea Beetles

Flea beetles are teeny tiny and mainly recognizable because of the way they “jump” away when disturbed, similarly to fleas. They’re found on many Brassicaceae and Solanaceae plants and leave small, round holes in the leaves, eventually creating a lacy appearance to the foliage. This leaves the plants with minimal ability to photosynthesize. Established plants can withstand some damage, but when seedlings are in the mix, they can cause problems. 

Row cover can be a helpful tool while plants are getting established, however keep in mind that if you’re flowering and fruiting plants are of concern, you’ll want to remove the row cover once they start flowering so they can get pollinated. As a last resort, we’ll recommend neem oil. 

Mexican Bean Beetles 

Bean beetles will also leave your foliage looking lacy! But they’ll stick to your beans, as well as your corn, squash, and okra (no, nothing is pest-free). In their adult stage, they look a lot like ladybugs except for their distinct orange color. The adults lay oval, slightly pointy, yellow eggs on the undersides of leaves. When they hatch, the larvae are bright yellow and soft, almost fluffy looking. 

Like the Colorado potato beetles, we recommend handpicking, especially when you’re protecting young plants. You can also use a floating row cover on crops until they start flowering to make sure they can get established. 

Japanese Beetles

Japanese beetles are the enemy to flower growers everywhere. However, this invasive species will feed on most anything. They’ll eat flower petals and skeletonize leaves on plants. Not to mention, their damage actually emits an airborne chemical that attracts even more of these beetles, letting them know that there’s food over here! So, if you see them, you’ll want to take care of it. These beetles are very easy to see with their glossy brown wings and iridescent green heads. Handpicking them is a good solution. They lay their eggs in the soil at the base of the plants they feed on, so beneficial nematodes or even letting your chickens run through the garden can help to mitigate next year’s problem. 

Slugs

Slugs are the bane of many growers’ existence. They often hide in mulch and come out at night to feed, meaning you’ll find a number of oddly shaped holes all over your crops with no clear indicator of “whodunnit”! However, if this has been your experience, you’re most likely working with slugs.

Every gardener has their own special trick for tackling their slug problem. These range from beer traps to lining copper wire around the bottoms of plants, which is said to repel them. Many of these don’t work 100% of the time, but they are definitely a great starting point! For extreme cases, iron phosphate is an organically certified — though perhaps controversial — slug repellent that works well. 

Squash Bugs

These bugs have explosive population growth, and while established cucurbits can definitely handle some squash bugs bothering them, young plants or later successions may run into some trouble. Their damage causes local necrosis of the leaves, leading to the eventual death of the plant. Looking out for the eggs is the first step to avoiding the takeover of the squash bugs! The oval eggs are golden yellow to reddish and can be found on the undersides of leaves or on the stems. They can be squished or scraped off and removed. You can also treat them by handpicking the gray nymphs and the brown adult squash bugs. 

Tomato Hornworm

These caterpillars wreak havoc on tomato plants but are pretty amazing to come across all the same. These stunning, though menacing, green caterpillars are the larval stage of the hummingbird moth! However, they have no place in your garden. The tomato hornworm will eat the leaves and the fruit of the tomato plants and can become a major problem if they’re left unchecked. There are a few ways to manage these munchers, though. You should keep a close eye on your tomatoes for defoliation and if you see them, remove them! Feed them to your chickens or squish. HOWEVER, if you see them with little rice-like grains coming off of their backs, let them live — for a little longer at least! These grains are the eggs of the parasitic Braconid wasp. In a few days, the caterpillar will die and the eggs will hatch, building your army of tomato hornworm parasites! If you have a particularly severe infestation, it can be treated with Bt, a naturally-occurring bacteria that targets soft-bodied insects. 

Cabbage Loopers

If you see white moths fluttering around your cruciferous vegetables, you’ve got cabbage loopers on the way. Look for the round, yellow eggs laid on the undersides of leaves. When found, crush them before they start chewing the foliage. If they’ve already hatched, you’ll see their dark green droppings towards the crown of the plant and notice defoliation. If left as-is, they can defoliate entire plants. Prevention is the best technique. Eggs typically get laid from May to June. Consider covering your brassicas with row cover so they can’t lay their eggs on your crops. You can squish the larval loopers as well, but be sure not to miss any! They’re good at camouflaging. You can also use Bt on these soft-bodied insects, however it won’t stop the moths from laying their eggs. 

Cucumber Beetles

The striped cucumber beetle and the spotted cucumber beetle may look slightly different, but they will cause the same problems. They can defoliate and damage fruit on cucurbits and can also carry bacterial wilt and the cucumber mosaic virus, which could mean big problems for the garden. Melons, cucumbers, and squash are all attractive to these pests. You can look for their eggs which are pale orange to yellow and laid in clusters on the undersides of leaves. A cucurbit trap crop, while keeping your true crop covered with row cover until flowering, can be effective. Once your trap crop is infected be sure to pull out and burn the plants to avoid movement from one plant to the next. Regular applications of neem oil can also help to slow population growth in extreme cases. 

Preventing Garden Pest Damage

Preventing garden pest damage using organic or regenerative practices isn’t always easy, but it can be rewarding! Through a combination of proactive, biological, cultural, and mechanical techniques, you can have a healthy, productive garden without using pesticides. 

In conjunction, this technique is often referred to as Integrative Pest Management (IPM). IPM represents a generally sustainable approach to pest management that combines multiple tools and techniques to improve the pest situation in your garden, as well as the garden ecosystem as a whole. 

Crop Rotation

Crop rotation is good for pest management as well as your soil health, which ultimately helps with pest management since healthy crops can better withstand pest pressure. Planting similar or the same crops in the same location multiple years in a row can cause a few problems. These crops are in need of the same nutrients every year, depleting the soil significantly if there isn’t any nutrient regeneration. Further, in many cases the summer's pests will spend the winter in the garden soil, coming out of the ground in spring. If they come out and find their food source planted right where they spent all winter, they’ll munch away happily! You, however, will find you have weaker crops all together. 

Sanitation

While “gardening” and “clean” don’t really go together, hygiene and sanitation certainly play their parts in the garden. Removing dying or diseased limbs or leaves from your plants can help stop the spread. Further, if your plants are heavily infested with pests, removing the entire plant can cut back on that population. That’s where trap crops come in — but we’ll get to that soon. Take care not to throw diseased or infested plants into your compost, as this will only spread the problem next year. Feed them to your chickens or toss it in the trash or burn pile! 

Using Physical Barriers in the Garden

Physical barriers in the garden can mean a lot of different things in terms of pest control. Buried fences or chicken wire can stop groundhogs or voles in their tracks, while tall fencing can (sometimes) keep out deer. Further, using row cover to protect tender seedlings as they’re getting established can keep pest pressure low until they're bigger and stronger. Just remember, if you’re covering a flowering plant, you’ll need to remove the row cover once flowering begins to allow for pollination and fruit development. 

Companion Planting and Trap Cropping

Companion planting and trap cropping are good ways to maximize garden space and fight pests. While the two are related, they are not exactly the same. Companion planting is the practice of planting different crops near each other that help each other grow in some way. This can be offering nutrient requirements, encouraging pollination of your vegetable crops, and pest control. For example, many herbs can mask the smell of your crops, hiding them from predators or drawing insect pests away! On the other hand, trap cropping for garden pest control means purposefully planting a crop that pests will go after, keeping your true crop hidden away, either under row cover or simply planted a little later. Trap crops should be removed from the garden once infested in order to remove the insect population.   

Using Beneficial Insects for Pest Control

Utilizing or encouraging beneficial insects for pest control in your garden is a great and natural way to encourage a healthy ecosystem while simultaneously combating pests. The best way to encourage beneficial insects in your garden is to plant a wide variety of flowering natives or annuals to attract them. They may already be there, in which case, the best way to protect them is to learn what they are and make sure you don’t remove them! 

Ladybugs

Ladybugs are common beneficial insects that you are likely familiar with. Aphids serve as their main food source, meaning if you have aphids, they’re probably there already! However, if you’re not seeing them you can purchase and release ladybugs into the garden. Keep in mind that once their food source is gone, they’ll head out to the next feast. 

Spiders

While many of us don’t love to socialize with spiders, we should let them be when they show up in the garden! Wolf Spiders and Orb Weavers are common, non-venomous garden spiders that eat many pests, including mosquitoes! 

Parasitic Wasps

We mentioned parasitic wasps earlier as they’re most well known for parasitizing the Tomato Hornworm. Other parasitic wasps will act similarly upon Japanese beetles, Mexican bean beetles, and squash bugs. 

Beneficial Nematodes

There are two types of nematodes you may have heard of: beneficial and parasitic. Parasitic nematodes suck the nutrients from the roots of your plants. Beneficial nematodes actually attack soil-borne pests and can be an effective part of pest management. They eat the larval stage of flea beetles, Japanese beetles, and carrot flies that overwinter in your garden. Beneficial nematodes are likely already in your soil, however, you can purchase and spray beneficial nematodes to bolster the population. 

Natural Remedies for Garden Pests

If all else fails, there are plenty of natural remedies for garden pests. We recommend using these additives as a last resort because there are pros and cons to each of these tools! However, in extreme cases, it can help to have these for your garden toolbox. 

Organic Pesticides

Organic pesticides are pesticides that come from natural sources, as opposed to unnaturally derived chemical pesticides. They are generally considered safe for humans and pets, but in some cases, they can harm beneficial insects. Because of this, it is important to take care not to rely solely on organic pesticides to combat garden pests.

Bt

Bt (or Bacillus thuringiensis) is a naturally occurring bacteria that is used to kill soft-bodied insects, like caterpillars and other similar larvae. There are different types of bacteria that act similarly and target different pests, however Bt is the most well known. It’s great for loopers or hornworms but may harm beneficial caterpillars as well. It is not harmful to humans or pets! 

Neem Oil

Neem oil has become very common in the garden to deal with sucking pests such as aphids and mites. When applied correctly, it should not be harmful to beneficial insects. 

Slug Repellant

Organically certified slug repellant does exist, though it’s somewhat controversial. The most effective slug repellents are iron phosphate based. This compound can be harmful to earthworms and dogs if overused or incorrectly applied. When used correctly, the organically certified slug baits and repellants break down quickly and become part of the soil. 

Monitoring and Managing Garden Pest Populations

Managing garden pests starts with keeping a close eye on your crops from the beginning of the growing season. Pest infestations can quickly get out of control, but regular and vigilant walks through the garden handpicking pests can keep everything in line. Ultimately though, the best garden pest management techniques involve bits and pieces from every corner of pest control to create a holistic approach to managing your garden. 

Preventing Pest Introduction and Spread

Learning about the life cycles and egg-laying timelines of your most invasive pests will help you to be proactive and mitigate the harm early in the season so that you can enjoy your harvests fully. Planning ahead also creates less work down the line. Set traps in the weeks before the adults come to lay eggs, inspect regularly to crush or remove eggs before they hatch, and handpick early before there are too many! 

When purchasing plant starts earlier in the season, take a close look to make sure there aren’t signs of aphids, mites, or anything else for that matter. Consider quarantining them for a few days away from your other starts to watch for any infestations. Quarantines will help you avoid introducing pests (or diseases) to the garden that you could otherwise avoid. If you do find an issue, remove the pests as best you can by hand or with treatments before introducing them to your other plants.

Final Tips for Keeping Pests out of Your Garden

Experimenting is the best way to find the pest management system that works for you. After a few seasons, you’ll know exactly what to do and exactly what works in your garden. Remember to utilize techniques from each section of this blog post to ensure a holistic approach to gardening that will benefit the ecosystem in the long term! 

Sow True Seed has an easy-to-browse selection of pest control products. We also want to see your garden thrive! Our newsletter offers regular (and free) garden tips including pest control tips and organic gardening methods. 

	Article Written by: Hannah Gibbons
	About the Author: Hannah Gibbons, an employee at Sow True Seed since 2020, has nearly a decade of experience in the agricultural industry. Their passion for environmental education and regenerative agriculture has been the cornerstone of their work, aimed at making gardening accessible to all.