Dealing with aphids once is stressful enough as it is; having to deal with these annoying pests over and over again is pure horror. But why do your houseplants keep getting aphids, and more importantly, how do you eliminate them once and for all?
Your houseplants keep getting aphids because of the following reasons:
- Straggler aphids are reproducing out of sight.
- Your houseplants sit too close to each other.
- You use garden soil as potting mix.
- Your houseplants are attracting aphids.
- You’re using too much fertilizer.
- Your houseplants are stressed.
In this article, I’ll talk more about the six reasons your houseplants keep getting aphids. I’ll also provide you with practical pieces of advice that you can use to prevent recurring aphid infestations from ever troubling you again.
1. Straggler Aphids Are Reproducing Out of Sight
As you may already have come to know from your first-hand experience, aphids are winged insects, and they can fly about.
This makes them incredibly frustrating to deal with, especially if you don’t like having bugs in your face, but it also means many aphids will be spread out in a radius around the main site of infestation.
It’s possible that even if you rid yourself of the entire aphid population on the infested plant, these stragglers reproduce and make an eventual comeback.
In fact, it’s quite likely, which is why you need to be very thorough with treatment. You can’t treat an aphid infestation with a single treatment session of homemade insecticide. You’ll need to persistently and regularly examine the infested plant for signs of new life.
If the aphids just keep coming back, you should resume going all out with insecticidal treatment to get rid of them once and for all.
Additionally, you should continue treatment for at least a week after most of the aphid population has been culled. This ensures any offspring will catch a spray of your insecticide, too.
How Quickly Do Aphids Reproduce?
Arguably the biggest reason that aphids are such a problem is how quickly they reproduce. A newborn nymph can mature and become an adult in just over a week.
In fact, adult female aphids can give birth to as many as 12 offspring a day. That comes out to about 80 new aphids per week.
Those numbers may seem ridiculous, but they begin to make a lot of sense once you see how quickly an aphid infestation can grow in real-time. These high reproductive abilities make it essential for you to get as many aphids as you possibly can.
Did I mention that aphids don’t need to mate to reproduce? The females reproduce asexually, meaning a single stray aphid could cause an infestation later down the line.
Okay, so we know that stray aphids present a danger warranting attention. But how do we deal with them?
The best way is to use traps.
How to Make a Dish Soap and Vinegar Trap
You can make a dish-soap vinegar trap to lure and kill stray aphids. This age-old recipe is both effective and convenient.
Here’s how to construct the trap DIY:
- Use an empty bowl. You can also use a tray or a plate. As long as it can hold some liquid, any container will work.
- Put a few tablespoons of liquid dish soap in the bowl.
- Add an equal amount of vinegar.
You have some flexibility in how much dish soap and vinegar to add, but you should try and add both liquids in equal parts to get the best results.
Now that the trap is ready, all you have to do is place it near your infested houseplants. I recommend using one trap per infested plant.
The vinegar will attract any stray aphids to the trap, and the dish soap’s thick consistency will trap whatever aphid comes into contact with it. Both liquids are also inherently toxic to aphids because of the chemicals they’re made up of.
Over the course of a few days, you’ll notice the trap become littered with aphid corpses. Once it has fulfilled its purpose, you can dispose of the contents inside the bowl.
How to Use Yellow Sticky Traps
Making DIY contraptions is fun and all, but not everyone has time for that. If you’d rather go with something store-bought or pre-made, I recommend using yellow sticky traps.
The way these traps work is simple — aphids are attracted to their vivid yellow color, and when they come to touch the trap, they get glued to it by the adhesive on its surface.
Yellow sticky traps are inexpensive and readily available in online and offline markets. They can save you a lot of headaches. Additionally, the dish soap trap and the yellow sticky trap will also lure in and trap any nearby pests other than aphids.
2. Your Houseplants Sit Too Close to Each Other
Since aphids are winged insects, they can traverse small to medium distances effortlessly. If your houseplants are located too close to each other, the infestation could spread to multiple plants.
Even if you happen to catch an aphid infestation early (which will make it much easier to deal with), it’s a good idea to isolate the infested plant until things are completely under control.
Isolation prevents other plants from getting infested, but it also keeps the aphids in a confined zone around the host plant, which allows you to better deal with them using insecticidal spray and traps.
If any of your houseplants are currently infested, you should isolate them immediately. After you’re done, inspect the rest of your indoor collection closely to ensure that none of the aphids managed to travel to another plant.
3. You Use Garden Soil as Potting Mix
There are many reasons you shouldn’t use garden soil as potting mix, and this is one of them.
Garden soil is usually laced with bugs, insects, pathogens, and pests. It’s not unlikely there’d be a live aphid, nymph, or aphid egg in there. I am a strong proponent of using high-quality, commercial-grade potting mix instead of homemade stuff.
The store-bought potting mix goes through a strict sterilization process, which rids it of any contaminants likely to give you problems.
Furthermore, a high-quality potting mix:
- Is fertile, as potting mixes are manufactured with soil nutrient composition in mind.
- Drains water better than standard soil, which is very important for potted plants, as poor water drainage can lead to overwatering.
- Has organic matter, which improves soil aeration and fertility. Organic matter is like a superfood for your plants.
Potting mix is the one thing you should not cheap out on. It will last you several years, so spending a few extra dollars initially will pay off.
4. Your Houseplants Are Attracting Aphids
Aphids are herbivorous insects that feed on plant sap. This is the nutritious liquid plants use to transport food all over their body. They’ll feed on the sap of just about any plant, but they, too, have preferences.
Aphids are particularly attracted to these popular flowers that are commonly grown indoors:
How to Deter Aphids From Your Houseplant
Luckily, there are several ways you can keep aphids from houseplants, even if the houseplants are something the bugs are attracted to:
Use Naturally Pungent Smells
If aphids are attracted to your houseplants, you can use naturally pungent smells to deter them from approaching.
Aphids and many other pests can’t stand the strong smell of garlic. You can make natural aphid-repellent spray using garlic cloves. Additionally, catnip and marigold are two plants that aphids would rather avoid.
Introduce Natural Predators Into the Ecosystem
To be honest, predators for pest-control purposes are usually only introduced in gardens or farmlands. As you can imagine, it’s not a great idea to bring in insect B to get rid of insect A in an indoor setting.
However, it can still be done safely and effectively when toned down. Especially so in this case, considering the “predator,” we’ll be bringing in — ladybugs!
Ladybugs look innocent enough; children are fascinated by them, and they don’t bite, usually. But most importantly, they eat aphids for breakfast, lunch, and dinner. Therefore, you could introduce a few ladybugs around infested plants.
They’ll help slightly reduce the existing population and deter new aphids from approaching and settling down while they stick around. The ladybugs alone won’t rid you of your aphid problems, but they sure will help.
You can get ladybugs at gardening or agricultural centers. They’re great pest killers, so most centers will have them.
5. You’re Using Too Much Fertilizer
Overfertilizing your houseplants, especially with nitrogen-heavy fertilizer, might be what’s causing them to suffer from recurring aphid infestations.
You’re probably wondering how fertilizer has anything to do with aphids. Well, contrary to what it may look like, aphids don’t feed on plant foliage.
They aren’t eating the leaves of your houseplant. They’re eating the sap inside these leaves. The loss of sap (nutritious fluid) causes leaves to starve, dehydrate, and fall off.
But to access this sap, they must penetrate the tube that carries it, which is why they prefer softer growth, as they have an easier time getting to the sap. As it happens, new growth encouraged by a high soil nitrogen concentration is very soft and supple — the perfect target for aphids.
For aphids, nitrogen-induced growth is basically food on a silver platter.
When dealing with an aphid problem, you should stop fertilization entirely. Yes, your plant will lose some nutrients, but the aphids will lose far more.
Remember, most houseplants really only need to be fertilized once every month or two during the growing season. If you fertilize them any more frequently, you may cause a nutrient imbalance or, worse, toxicity in the soil.
Overfertilization can have disastrous effects.
6. Your Houseplants Are Stressed
Houseplants need to be cared for. Some more than others, but all plants have their needs. Failing to care for your houseplants can cause them to suffer from environmental stress.
Plants under environmental stress are prime targets for pests such as aphids because of their reduced defensive capabilities. Aphids prey on weak plants.
Plants also have their own clever defense mechanisms against pests. A healthy plant will be able to fend off aphids much better than a weaker one of the same species.
Therefore, you should try and keep your plants healthy and happy. The best way to deal with an infestation is never to allow it to establish itself in the first place.
Let’s discuss some of the most common conditions that undermine affected plants’ ability to defend themselves and how to deal with these conditions:
Your Plant Is Receiving Inadequate Sunlight
Sunlight allows plants to create food from the nutrients they gather from the soil in a process called photosynthesis. A plant that doesn’t get enough sunlight ends up malnourished and weak, so you should let your indoor plants get as much sun as possible.
Indoor plants usually need 4 to 6 hours of moderate-intensity sunlight per day. These are best placed a few feet away (0.61+ m) from a window.
Some plants, such as the daisy and sunflower, need a minimum of 6 hours of direct sunlight. These are best placed under direct sunlight. So, for example, an east-facing window or a balcony.
Only a handful of indoor plants can survive on less than 4 hours of sun long-term. And even those plants would be better off if they received more sun.
I recommend you be generous when it comes to how much sunlight you allow your plants to receive. Damage due to excessive sunlight is rarely an issue in an indoor setting. Still, if your plant gets sunburned, you can salvage it.
If you suspect any of your plants aren’t getting their fair share of the sun, all you have to do is move them closer to a window. It’s a simple, effective fix.
You’re Underwatering Your Plant
Water, like sunlight, is a reactant required for photosynthesis. It’s also utilized in metabolic activities.
Now, underwatering is fairly uncommon. As long as you don’t forget to water your houseplants entirely, they probably won’t suffer the long-term consequences of dehydration.
Plants are pretty resilient. Save for a few water-loving varieties, most houseplants can go weeks without being watered. Still, you should be fairly consistent with how often you water your plants.
I recommend watering deeply and then letting the soil dry out. Stick your finger 2 inches (5.08 cm) deep into the soil to check the moisture levels.
If there’s still noticeable moisture, leave the plant be. If the soil is nearly dry, go ahead and water it thoroughly. This way, you can water your houseplants less frequently but satisfy their water requirements all the same.
You’re Overwatering Your Plant
Overwatering is a hidden menace. You may be surprised to learn that it’s the most common cause of indoor plant death.
You see, we tend to overestimate how much water plants need. As I mentioned earlier, most plants can go weeks without a drop of water before they begin to suffer from permanent damage.
Overwatering damages plants by killing their roots, as roots standing in water can’t breathe. If they stay in water for too long, they suffocate and die. The remaining plant is left behind with no way of supplying itself with nutrients, so it usually dies too.
Overwatering typically results from too-frequent watering. This is why I recommend watering deeply and thoroughly, as it allows you to water your plants less frequently.
As long as you let the soil dry out between waterings, your plants should be safe from overwatering.
However, it’s important to have good water drainage for when you unintentionally overwater a plant. Water drainage depends largely on the quality of your potting mix. You also must use pots with drainage holes.
Your Plant Has Unsuitable Temperature and Humidity Levels
All plants have a temperature range they’re comfortable in. When they’re in temperatures outside this range, they have to work overtime to compensate.
Plants don’t have great thermoregulation, though. They really can’t tolerate being outside their survivable temperature ranges for long.
A plant in a temperature too cold will suffer from frost damage. In temperatures too hot, it will end up dehydrated. You should limit your indoor collection to only those houseplants you know are suitable for your locale.
Humidity is another major player in determining plant health. Except for a few drought-tolerant species (such as cacti and succulents), most plants prefer high humidity, as it helps them preserve water.
40 to 60% humidity will suffice for most houseplants, although some prefer even more.
You can increase the relative humidity experienced by your houseplants by placing them in bathrooms and kitchens. You can also use a pebble tray to moisturize individual plants. Alternatively, run a humidifier.
Your Plant Has Soil Problems
Indoor potting soil can develop the following problems:
Nutrients in soil run out with time and need to be replaced somehow. You should use fertilizer monthly or every two months to do so. However, avoid using fertilizer during an infestation.
Acidity or Alkalinity
Soil pH that’s too high or low can cause problems with nutrient absorption. You can check soil pH using a soil testing kit.
Heavy soil is usually a problem when you use garden soil as your potting soil. Garden soil is heavy and difficult for roots to grow through. It also disrupts water drainage, increasing the likelihood of root rot.
If you’re using a high-quality potting mix, you probably won’t run into soil problems for a long time.
Your Plant Is Experiencing Transplant Shock
When plants are dug up and transplanted into different growing media, they temporarily go into shock. They need some time to readjust to their new environment. During this time, they’re particularly weak to pests.
Transplant shock is to be expected when you change either the potting media or container size. You’ll have to transplant your houseplants into larger containers every few years so they don’t become pot-bound. But other than that, I suggest you refrain from unnecessary transplantation.
Additionally, using a potting mix similar to the original growing media of the plant can help reduce transplant shock.