Houseplant Pests: Best Prevention Practices

* Image sources: All images used in this post are from the author

Does the featured image of this post put you off a little? I feel you! The image is from a plant in the inner yard of the accommodation in Brazil where I recently was, and that leaf is full of scale mites.

Nobody wants pests like that on their houseplants which is why in this post we’ll go through the best prevention practices against pests in houseplants. Pest prevention has a lot to do with your regular plant care routine:

Optimal pest prevention for houseplants involves maintaining proper watering, controlling indoor humidity, ensuring suitable light exposure, and regular health checks. Avoid overwatering, use a humidifier in winter, and match each houseplant’s light requirements.

Let’s talk about what an appropriate plant care routine entails and what else you should consider to prevent pests in your indoor plants.

Protect Houseplants From Pests: Establish Ideal Plant Care And Environment

There are two main reasons for pests or diseases to spread among your houseplants:

  • The soil is too moist over longer periods (Prevent overwatering!)
  • The humidity levels are too low (Use a humidifier!)

There are of course many more reasons why a houseplant could get pests but the soil moisture and humidity levels make the biggest difference.

I think it is worth mentioning here as well that it is not the end of the world if one of your houseplants happens to have a pest. It can happen to anyone that one of their houseplants gets infected by some pest or a disease, it has happened to me as well a couple of times. Sometimes it is hard to figure out why.

After all, plants are complex beings, each plant type evolved in a specific natural habitat. Trying to mimic various natural habitats all in the same room indoors is not an easy task as you can imagine, even more so in winter when the heating is on.

However, there are a few simple but effective ways to prevent houseplants from getting pests and keeping them healthy.

No Overwatering And Never Let Your Houseplants Sit In Water

Overwatering is among the main reasons for indoor plants to perish. Most plant owners tend to be overly kind when watering their houseplants, thinking the more the better – even though less is more in this case.

To prevent overwatering, do a weekly plant check for soil moisture. Stick your finger into the upper inches of the soil. If it is dry, then give it a rinse. If it is still moist, then wait with watering. During hot summer weeks, you can check on your plants every couple of days instead of weekly as they might need more water.

Good to know: Not all water is the same for plants. Tap water, distilled water, or even fish tank water have varying qualities. Intrigued? Find out more about which type of water is best for your houseplants and how to improve your water quality for plants!

As a rule of thumb, it is good to remember that it is better to give less water but more often rather than giving a lot only once.

For more tips on how to water your indoor plants the right way, here’s a link to my complete watering guide for houseplants!

How do you know if you have given your plants too much water? Check the saucer or pot of your plants about 15 minutes after watering them. If there is water in the pot or the saucer, this is the excess water that you should pour out. If you leave excess water in the pot, your plant will sit in water which can cause root rot (= the effect of overwatering).

By watering in appropriate amounts, your houseplants will stay healthy and resistant to pests. I recommend adding a quick health check to your watering routine. This is not only an almost meditative practice, brushing through the leaves and stems but it also helps spot any signs of illness before it spreads. Check out my step-by-step plant health check to know what to look out for!

Tip: Are you going on holiday soon? Don’t forget about your houseplants! Find out in my post linked here what the best methods are to water your green fellows while away.

Use Good Quality Organic Soil

Good quality soil will make your plants happier because of all the good ingredients it comes with, especially the drainage materials. Along with appropriate watering of your plants, this is another main asset to boost your plants’ resilience against pests and diseases.

Why is drainage important? It is the main prevention method to keep the soil aired and loose instead of clogged up and too moist, thereby suffocating your plants’ roots. If you’re not sure how to provide appropriate drainage in whatever type of pot or what drainage material to use, I’ve covered this topic in my post linked right here.

I recommend opting for good quality organic soil as it is the most natural and doesn’t pollute the environment with unnecessary chemicals.

Another benefit of good quality soil is that chances are much less that there are eggs of bugs in it. With cheap soil, it happens way more often that there are some type of eggs left in the soil such as fungus gnats (those little nasty flies).

Even in good quality soil, it can once in a while happen that there are fungus gnats in it. To make sure there are none, you can spread the fresh soil on a newspaper on a table outside and let it dry out completely in the sun. Fungus gnats need moisture for their eggs and larvae to survive. If no outside table (or no sun) is available, spread the soil on a baking sheet and let it dry in the oven at no more than 180 Fahrenheit (80 Celsius) for about 30 minutes. Baking time depends on initial soil moisture.

Tip: This process of drying out the soil is also called sterilizing the soil. When buying fresh soil, look out for soil that is labeled as sterilized. That way, you don’t have to make the extra effort and can still be pretty sure that there are no sort of pests or bugs in the fresh soil.

Use Fertilizer Sparingly Especially In Winter

Too much fertilizer can lead to an overactive growth of the plant in phases when it would normally rest such as in wintertime. This can disturb the natural metabolic cycle of the plant and in the long run, can harm its natural resilience to pests.

Furthermore, too much fertilizer can lead to unwanted residues and build-ups of nutrients in the soil. Just as with human food, excessive amounts of for example sugars, fats, and salts are unhealthy while little amounts are good. The same goes for plant food.

Hence remember this rule of thumb: Fertilize every two weeks in summer and only once a month sparingly in winter.

Tip: Did you know how many different types of natural fertilizers there are? No need to use harsh chemicals! From banana peels to pasta cooking water, find out which homemade ingredients you can add to your plant water to naturally fertilize your houseplants!

Choose A Spot With Appropriate Light Condition For Each Houseplant

The light conditions at the chosen spot in your home should be more or less right for a plant to stay healthy. Inappropriate light spots increase the chances of overwatering your plant.

An example: Let’s say you water all houseplants each week but one of the plants is in a spot that is too shady for it. Less light means less photosynthetic activity and overall less water intake of the plant. In that spot, that plant might only need a rinse every three weeks because it is almost inactive. You as a plant owner though think that this plant surely must need water like all the others, and still water it every week. The result is overwatering and eventually root rot.

Choosing the right light conditions is important for a healthy plant metabolism. It doesn’t need to be 100% accurate – that is incredibly difficult to achieve for each plant in a regular household – but at least close to it. Some people just place plants wherever they think it looks pretty. Please, try to match beauty with appropriate light instead!

Do you have no idea which spot in your home has what light conditions, or even how much light each of your plants needs? Here’s how to find out:

Keep the Humidity Levels Indoors At About 60% Year-round

Indoor plants have a hard time during winter. The heating system decreases humidity indoors to very low levels. Even our skin can feel that and it becomes itchy and dry if we don’t raise the humidity levels in our homes. Most common indoor plants come from rather tropical regions, they would love humidity levels of up to 90%. For our buildings though, that is too much humidity.

A good compromise that is healthy for plants, humans, and our buildings alike is around 60-70% humidity indoors.

An easy way to increase humidity indoors is by using a humidifier. There are plenty of options these days, they come in all sizes and shapes and with varying technologies. Feel free to choose whichever model suits you!

Another advice is to regulate your heating well such as keeping it at a normal level and use a timer to lower the temperature at nighttime.

Also worth mentioning here is the practice of misting plants which many plant owners seem to be adoring. Unfortunately, I have to tell you that this is more of a plant myth than an actual help to increase humidity – find out why in this post linked here.

Tip: A humidifier is the most efficient way to raise humidity but there are several other options to increase humidity. Check out how to increase humidity in your home in this post right here!

Use Organic Oils Neem Oil to Prevent Pests

This method is not just a prevention method but also a remedy. Neem oil is a natural bug killer and also helps against fungi or other diseases in the soil.

If one of your plants gets infected, neem oil is an efficient and completely natural oil to use against the pest. As a prevention measure, I recommend using only a few drops of oil mixed in water and spraying it sparingly on the plant.

Related Questions

How to Quarantine a Houseplant?

If one of your houseplants gets infected, then it is best to quarantine that plant for at least a month. Place the affected plant in a separate room with no other plants in it. This might need a bit of rearranging for your indoor jungle but it is worth it as no other plant will get infected.

During one month, treat the quarantined houseplant against the pest and check weekly for improvements. Once the plant has been rid of pests for at least two weeks, you can move it back among the other plants.

I recommend quarantining for at least a month if not two. Better wait a little longer if possible.

What Are the Most Common Houseplant Pests?

The most common houseplant pests are:

  • Fungus gnats (little black flies living in soil)
  • Spider mites (create a web-like texture around leaves and stems)
  • Scale mites (are flat with a hard shell and seem to be glued to the leaf’s surface)
  • Mealybugs (white insects stuck to the leaf’s underside, bodies are soft and can be crushed)
  • Thrips (black or white insects that live on the leaves, drying them out)

Most common houseplant pests love dry and warm climates. Our wintertime indoors is just perfect for them if you don’t increase the humidity levels in your home.

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