“Pests” are part of the natural ecosystem. Getting rid of them is an impossible feat, but managing them will help keep populations at tolerable levels for both the plants and the people who enjoy the plants. There are a few basic ways to tackle pest management, but an integrated approach will be the most effective. Integrated pest management (IPM) uses a combination of controls to minimize the need or overuse of pesticides. We like to take an organic pest management approach. Even if we get to the point of needing to use a “chemical” control we use natural remedies that are safe for the environment. More on that later.
To understand how to manage pests in the garden, we first need to understand why they attack plants in the first place. Pests most often attack weak plants or plants that are already compromised. Plants with weak root systems are most susceptible to attack. This is most often due to root rot from overwatering, underwatering, or poor drainage. A greenhouse environment has the potential to create thriving pest populations due to the lack of natural predators, elevated humidity levels, and potential air circulation issues. These situations can be avoided using the methods presented in this article.
Steps to Establishing an Integrated Pest Management (IPM) System
Prevention
The first step to integrated pest management is prevention. By preventing issues from arising in the first place, we ensure that everything is better off in the long run. Though it is easier said than done, you can prevent the introduction of pests by starting plants from seed, quarantining purchased plants before bringing them into the dome, creating and maintaining healthy soils, installing rodent protection during garden construction, and ensuring proper airflow.
Monitoring
The second aspect of integrated pest management is monitoring. Pay close attention to the state of your plants and garden overall. Pest populations can easily balloon out of control if left unchecked. Many pests are small and you may not notice the pests themselves until your plants begin to show signs of disease.
Check the undersides of leaves regularly for small insects like thrips, spider mites, aphids, and whiteflies. Mealybugs and scale often hide in the nooks and crannies of trees. Pill bugs will hide in mulch or under pots, anywhere that is cool and damp. Powdery mildew occurs when plants are not provided enough airflow. Ants are a sign that you may have other pests present because they like to feed on the honeydew created by aphids, whiteflies, and mealybugs. We have detailed information about how to manage all of these pests, so check out those articles and videos for pest-specific information.
Action Tolerance
The final step before implementing controls in integrated pest management is establishing a tolerance threshold. As we mentioned in the beginning, having zero tolerance is not realistic. This “action tolerance” is really going to depend on you as the gardener and it will vary from person to person. Some people don’t mind pill bugs and do not find them harmful. Some people are more tolerant of washing off a few aphids before making their salad than others. Plants are resilient and can often survive and even thrive in less-than-ideal conditions, but it is more often than not the gardeners that take the most offense to garden pests.
Mechanical Controls
The first control in an integrated pest management approach is mechanical. Mechanical controls are methods that physically remove or prevent pests. This can be anything from manually picking them up and removing them, trapping them, and creating physical barriers to keep them away. This is always the best place to start with IPM as these methods are simple and long-lasting.
Traps
Traps can help control several pests such as rodents, wasps, flies, ants, and pill bugs. Hanging sticky traps help control whitefly populations. Sticky traps laid flat within the garden bed can capture roly pollies, slugs, and ants. Live traps can be set for mice and other mammals so they can then be relocated far away from your garden. Sliced potatoes and beer traps can also help to trap pill bugs.
Physical Barriers
Physical barriers include utilizing screens and sealing cracks or gaps where pests may be able to enter. Screen doors are a great option for greenhouse environments and if necessary, hardware cloth can be used on the lower vents to keep things like grasshoppers and rodents out. Hardware cloth can also be installed underneath the greenhouse to prevent burrowing intruders. We offer detailed instructions on how to install the rodent protection option with our Growing Dome installation instructions. Floating row covers can also be used to help protect young plants from pests.
High Pressure Hose
Sometimes a high-pressure hose is the most effective solution for removing pests. This method can easily knock pests like aphids off the plant. However, be mindful that it may not be well suited for young tender plants and works best on mature plants that can withstand the pressure.
Biological Controls
Biological pest control involves introducing natural predators of the pests into your garden or beneficial pathogens to improve the ecosystem. These are especially helpful in integrated pest management with a greenhouse where natural predators for pests are often lacking. This method can be combined with certain techniques for mechanical pest control. Keep in mind that all things stick to sticky traps, but screens will help to keep some of the pests out and the beneficial insects in.
Beneficial Insects
Beneficial insects are a gardener’s best friend. Not only do they help to control pest populations, they also help to pollinate. Ladybugs and lacewings are a good option for aphid control, but we have found that winged insects tend to not stick around. We like to opt for mantids as they rarely fly. Regardless of the beneficial insects that you choose, it is often the second generation that will make the largest impact on pest populations. The first generation will mate and lay eggs. Once those eggs hatch and mature to adolescence they will begin to prey on the other pests. Turns out all teenagers have large appetites, not just the human ones.
Beneficial Pathogens
The main pathogen that is beneficial to gardeners is mycorrhizal fungus. Mycorrhizae is a symbiotic relationship between the roots of a plant and fungus in the soil. The roots provide the fungus with sugars and carbon and the fungus provides water and nutrients to the plant in return. Introducing mycorrhizal fungus to your soil will benefit your plants by making them have stronger root systems and thus make them less susceptible to diseases and more tolerant of pests.
Predatory Plants
Predatory plants include venus fly traps, sundews, and pitcher plants. These plants are carnivorous and feed on many garden pests.
Cultural Controls
Cultural controls are ways in which a gardener can manipulate the natural environment to make it less suitable for pests. These controls are imperative to a successful integrated pest management approach. Choosing the right crops, planting them in the right location, and closely monitoring moisture levels in the soil and humidity in the air can all help to mitigate pest infestations.
Soil Health
A healthy garden starts with healthy soil. We recommend using soils rich in organic matter which will help plants develop healthy roots. Paonia soil is one of our tried and true favorites. We also like using mushroom compost for its moisture-retentive properties and slow release of nutrients. There are ways to amend your existing soil to improve it. Before adding any type of amendment it is best to test your soil to see what types of amendments would be best.
Crop Spacing and Rotation
Everyone likes their personal space and plants are no exception. When gardens are overcrowded pests can easily move from plant to plant and diseases are also easily transmitted. Look at your seed packets for information on the size of the plant at maturity and spacing recommendations.
It is also important to rotate your crops. Pests can take residence in the soil and if you continue to plant the same crops in the same places, the pests will always have their favorite food source. Rotating crops also helps to prevent nutrient depletion of the soil. Nutrient-depleted soils can lead to weak plants which are more susceptible to infestation.
Companion Planting and Trap Crops
Companion planting is the practice of planting multiple crops in close proximity for increased productivity, pollination, and pest control. For example, a “salsa garden” is not only delicious, but a great example of companion planting. Tomatoes, peppers, cilantro, garlic, and onion are all companions. Garlic and onions deter spider mites, tomatoes provide some shade to the peppers in the heat of the day, and cilantro can help deter whiteflies.
A trap crop is a plant that is used to attract pests and keep them off of your more valuable crops. Examples of trap crops include nasturtiums and marigolds. We frequently use these trap crops because they add beauty to the garden and serve a very important role. They are also quick-growing plants, so it is easy to rip them out once infested and start again. We like to always have some of these flowers started in trays so that we can employ them as needed.
Watering Practices
Underwatering, overwatering, and inconsistent watering can all lead to pest problems. We like to use a moisture meter to help us determine when it is time to water. The surface of the soil will dry out more quickly than the soil below it, so you can also use your finger to test for moisture. Read more about watering best practices in our in-depth article.
Improved Ventilation
Greenhouse environments can lack proper airflow which can lead to large pest populations and powdery mildew. Having proper ventilation in a greenhouse is key to temperature and humidity control, but bringing in cooler outside air and exhausting hot air out is not always enough. Horizontal airflow is also important to keep the air within the greenhouse circulating. Try adding an oscillating fan to your greenhouse if you notice that pests are above your established tolerance level.
PRO TIP: Adding ventilation is great, but without proper pruning, the results will be negligible. Plants like tomatoes and fig trees can tolerate heavy pruning and using stringers to make them grow in the desired direction is also good practice.
Greenhouse Hygiene
It is also advisable to remove all the dead, dying, or diseased plants from your greenhouse. After pruning plants make sure to remove all debris from your greenhouse. Having plant material on your pathways or in your garden beds can create a breeding ground for more pests. Never place diseased or pest-infested plants in your compost for the same reason.
Organic Chemical Controls
Chemical controls should be used as a last resort in integrated pest management and should always be as organic and natural as possible to protect the ecosystem of your garden and the people that interact with it. We try our very best to avoid using anything with the word “cide” in the name. In fact we try our very best to make the solutions that we use in our gardens.
Our Tried and True Natural Pest Control Solutions
- 1 TBS Peppermint Castile Soap in 1 Quart of water for white flies, mealy bugs, spider mites, and aphids
- 1 Cup Sugar, 1½ TBS Borax, and 1 ½ Cups warm water for ants
- 2 TSP Apple cider vinegar, 2 Drops dish soap, and Sprinkle of sugar for gnats
- ½ Cup of chili peppers blended with 2 Cups of water for aphids
- 1 TBS Sodium Bicarbonate, 1/2 TSP Castile Soap, 1 Gallon Water for powdery mildew
There is no “one size fits all” approach to integrated pest management, but we hope that you are able to take these ideas and build your own organic integrated pest management plan. Learn how to combat the top 5 greenhouse pests with our free PDF download by filling out the form below!
