By the time the cooler weather of fall arrives, I’m thrilled to take a moment to relax and enjoy the garden. Unfortunately, aphids aren’t quite ready to settle down for the year. These tiny pests remain active in the fall, and if left unchecked, they can cause significant damage to your plants.

Controlling aphids in the fall garden is similar to managing the pests during other times of the year. However, there are a few specific tips you can keep in mind to keep these pests at a manageable level.

I’ll share how to identify aphids, prevent them from becoming a problem, and control them when they start damaging your plants.

What Are Aphids?

Small sap drinkers weaken growth with their constant feeding.

Aphids are tiny sap-sucking insects that feed on a wide variety of plants. They use their piercing and sucking mouthparts to drink sap from plants. This feeding weakens the plants, and it can also spread diseases.

You can find dozens of types of aphids that range in size and color. Green, red, yellow, and gray are a few colors you may find. Although the different species may vary slightly in appearance, they all have a pear-shaped body that’s less than a quarter of an inch long.

A few aphids won’t cause serious issues to your plants, but these pests can quickly multiply. Adults can produce up to 80 offspring in a week, although their reproduction rates are lower during the cool fall weather. That’s one reason why it’s important to get rid of aphids as soon as you spot them.

Tips for Controlling Aphids in the Fall Garden

If you want to control aphids in the fall garden, follow these tips to prevent and manage the pests.

Pay Attention to Overall Plant Health

Even moisture in soil supports steady plant health.

Healthy plants are better able to fight off aphids, so pay attention to your overall plant health. Focus on building soil that’s rich in organic matter and beneficial microorganisms, and balance nutrients for optimal plant health. Avoid applying excessive nitrogen fertilizer, as this creates plants that are more susceptible to aphid attacks.

Water your plants regularly to maintain a moist but not soggy soil. It’s okay to expose most fall crops to near-freezing temperatures and light frosts, but cover your plants with row cover if you expect a hard freeze.

Regularly Inspect Your Plants

Taking action after early signs on leaves saves plants from stress.

Since these pests reproduce rapidly, spotting them as early as possible is crucial for managing aphids in your fall garden. Spend at least two days a week walking around and carefully inspecting your plants. Aphids attack a wide array of fall crops, so look at all areas of your garden.

Watch for the aphids themselves as well as signs of the pests. You may notice honeydew, a sticky substance secreted by aphids. Sometimes, black fungus grows on the honeydew, leading to black leaves.

If aphids are present in large numbers, you may also notice yellowing foliage. When you spot discolored leaves, take a closer look for aphids.

Check Under Row Covers

Venting row covers prevents moisture from causing leaf troubles.

As cooler fall temperatures arrive, many plants benefit from being tucked under a protective layer of row cover. These lightweight covers allow light and water to pass through while warming the plants and protecting them from harsh winds. They also help keep out pests like cabbage worms, harlequin bugs, and flea beetles.

It’s easy to leave the covers on 24/7 when temperatures rarely reach above 50°F (10°C), but I recommend removing them when the weather allows. This venting allows for airflow that discourages fungal diseases, and it also allows you to check for pests.

I’ve made the mistake of leaving row covers on fall crops for multiple weeks before removing them. When I lifted the coverings from the plants, I saw that I had created the perfect warm environment for aphids to thrive. My storage radishes and turnips were overtaken by the pests and beyond the point of saving.

Regularly removing your row covers allows you to spot aphids when numbers are still low, making it easier to control them.

Encourage Natural Predators

Ladybugs happily patrol gardens, feasting on tiny intruders.

If you’re worried about aphids in the fall garden, encouraging natural predators will help prevent and control these annoying pests. Insects, including ladybugs, green lacewings, hoverflies, and parasitic wasps, feed on aphids, helping to keep their numbers in check.

You can take a few steps to encourage these good bugs in your garden. First, plant an array of flowering plants, especially those that bloom in the ​​fall, like asters and goldenrod. These flowers produce nectar and pollen that support the adult predators, allowing them to produce larvae that will attack the aphids.

Adding a water source to your garden will also encourage beneficial predators to visit and stay in your garden. A bird bath or even a small dish of water works well.

Finally, avoid spraying broad-spectrum insecticides that harm a wide variety of pests. Although these products will kill pests, they can also harm beneficial insects. Avoiding insecticides or choosing a product that only harms a single pest family are the best options. If you decide to spray a general insecticide, spray it in the morning on a calm day, and only apply it to the target pests.

Remove Aphids ASAP

Clipping damaged leaves helps plants bounce back stronger.

Once you spot aphids in your fall garden, it’s important to remove them right away. You may not think a few aphids are a problem, but they can quickly multiply into hundreds. Removing small numbers of the pests will save you time and protect your plants from damage.

If you see aphids on your plants, you can dip a rag in soapy water and use it to wipe them off. This method works well if you only spot a few of the pests on your plants. 

Another option is to use pruners to clip off infected leaves. This method is most effective when the pests are concentrated on just one or two leaves, rather than the entire plant.

Resort to Sprays as a Last Effort

Neem oil offers plants a safe protective shield.

If your plants are covered with aphids, natural predators won’t be able to keep the pests in check. Similarly, removing the pests by hand is an unrealistic option. Turning to organic sprays is your best option to save your plants.