Aphids may be tiny, but they have many ways of getting inside your house or greenhouse and onto your indoor plants:
Aphids can be carried in on people’s clothes, a pet’s coat, or on plants bought at a nursery or store. Some aphids fly and float on the wind, so they enter through open windows or doors. If you put your plants outside, aphids might crawl, fly, or be carried onto these plants by ants.
Aphids are attracted to indoor plants because your home or greenhouse is warm and kept at a fairly stable temperature, and the plants inside are usually given good care so they grow well. This combination gives aphids a comfortable environment and a consistent source of their favorite food – the sap in healthy plants. Knowing how aphids get in can help you keep them out permanently, and save your plants from aphid destruction and perhaps even death.
Where indoor aphids come from
Aphids get on plants in homes and greenhouses in the following ways:
Aphids come in with infested plants or bunches of flowers
The most common way for aphids to come indoors is on plants that are brought into the area. If you buy plants from a nursery, store, or garden center, or someone gifts you a plant or flowers, the plant may have aphids or aphid eggs on it.
When you bring an infected plant or flowers inside, the aphids hatch or reproduce quickly in the warm environment. In fact, aphid eggs start hatching when temperatures reach only 50 °F (10 °C).
They soon move to other nearby plants to start new aphid colonies.
If you have aphids on one plant, you will probably soon start finding aphids on other plants – especially if the plants are similar because aphids tend to feed on the same types of plants.
Aphids are carried inside by people
Though not as common as plant-to-plant infestation, aphids can catch a ride with you or someone else. Aphids are so small that you probably won’t even see them on your clothes, but if you walk past a plant or tree infested with aphids, some might drop onto you or drift onto you in the wind.
Aphids may cling onto clothing, pets, or garden tools, and get taken inside. Once aphids are in your house or greenhouse, they crawl or fly onto plants that they can feed on.
Aphids fly or float in
When the conditions are right or the seasons are changing, many types of aphids have babies with wings. These aphids are flying aphids, and they soon leave the colony in search of new food sources.
Flying aphids can enter your home or greenhouse by flying or floating in on the wind, coming in through open doors or windows.
Aphids arrive in the soil you use
Most aphids live on plants, eating the softer, fleshier parts of the leaves and wherever there’s new growth or budding. But some aphids, called root aphids, live in the soil.
Root aphids lay eggs in the soil, which can stay alive through the cold winter months, only to hatch in spring or when they’re warm indoors.
If you use potting soil for your indoor plants or greenhouse plants, or you reuse soil from other plants, and there are root aphids or root aphid eggs hidden in this soil, you will soon have an aphid infestation.
While above-ground and root aphids both cause a lot of visible damage and even kill plants, it’s easier to find out if you have above-ground aphids just by inspecting the plant to look for them.
But you often won’t be able to see root aphids, and it can take a while for you to notice the damage they are causing.
At first, you might notice that your plant is struggling to grow because the root aphids are sucking out all the plant’s nutrients. Over time, the plant’s leaves will turn yellow or brown, and the plant will eventually wilt and die.
If you pull the plant out of the pot, you will probably see callouses or growths on the roots and knotting in the roots because the roots couldn’t grow properly with the aphid infestation.
If your plants ever go outside, aphids could find them
If you ever put your indoor plants outside, for whatever reason, there’s a chance the plants can become infested with aphids from your yard.
Aphids may drop to the ground and crawl onto your plants, they might fly onto your plants if there are winged aphids in the colony, or they can be carried onto your plants by ants.
There are a few species of ants that farm aphids. These ants love eating the sweet honeydew that aphids release when sucking the sap out of plants. So ants farm aphids by taking care of them, protecting them from predators, and moving aphids from plant to plant to find new sources of sap.
How to prevent and get rid of aphids on indoor plants
Here are my top tips and best products available on Amazon to get rid of aphids that you find on your indoor plants:
- Before buying plants, check them thoroughly for any signs of aphids or aphid damage. Check the softer parts of the plants, under the leaves, the base of the plant and the soil, and any new growth on the plant, looking for aphids. If the plant is wilted or has yellow leaves, it may be infested with aphids or root aphids. You should not bring these plants home with you.
- Quarantine any new plants or flowers that you bring inside. Keep new plants in a separate area away from your other plants, at least for a week or two. By the end of this isolation period, you should be able to tell if there are aphids on the plant by inspecting it or looking for damage.
- Spray down your infected plants with soapy water. Simply mix 2 tablespoons of Dawn dish soap (this one works best) with a gallon of warm water. Be sure to use soap and not detergent, because soap kills aphids. For full instructions on how to make and use this soap spray, along with precautions so you don’t kill your plants, click here for the full blog post.
- If you don’t want to spray down your plants with soapy water, wash them down with a strong spray of clean water from the hose or wipe them down with a damp paper towel. This method might work if the colony is not yet well established, and you don’t have many aphids.
- Buy branded potting soil from a reputable company, and don’t reuse soil or pots that a plant has died in. If you want to be sure and sterilize soil before you use it, preheat the oven to 180 °F (80 °C). Put the soil in an oven-proof pan and make sure it’s no more than 4 inches deep. Place the pan of soil in the oven and leave it to bake for half an hour. Don’t make the oven hotter than this because it can produce toxins.
- Use an insecticide to kill the aphids. There are all-natural neem sprays and highly-rated branded insect killer sprays available (that also kill sooty mold caused by aphids) – just make sure that whatever you choose is suitable for indoor use and that you follow the instructions carefully.
- If parts of the plant are badly infected, trim off these parts to remove them. Cover the infested areas with a plastic bag and cut just below the top of the bag, leaving the infested part inside the bag. Seal the bag and throw it away. This ensures that none of the aphids have a chance to drop off and get away. Sterilize your scissors or pruning scissors with alcohol or soap and sunshine after.
- Dust diatomaceous earth on top of the potting soil of all your indoor plants. When aphids walk on it, their bodies are cut and the aphids die. This is a very good, cost-effective, and eco-friendly method to kill aphids moving between your plants or on your potting soil. You’ll need to reapply this earth after watering, once the soil is dry.