Can You Put Styrofoam in the Bottom of a Planter?

So many people enjoy gardening–there’s something about taking care of your plants, arranging them in an aesthetically pleasing layout, and watching them grow into something exquisite. I can promise that the benefits of gardening outweigh the stress you might experience during the process. Of course, knowing the suitable materials for planters can be a game-changer if you keep plants.

You can put styrofoam at the bottom of your planter since the material is lightweight, easy to work with, helps with drainage, and doesn’t cost much. However, it can be dangerous to your plants, especially if you use pots without sufficient drainage or drainage holes.

Unlike soil, styrofoam doesn’t retain moisture, which can be both a benefit and a problem. So, while it won’t get soggy or moldy, it can also severely impact the roots of healthy plants by interfering with their growth. In the rest of this article, I’ll explain in detail the effects styrofoam can have on your plants and highlight alternative materials you can put in the bottom of your planter.

Why Do People Use Styrofoam in Planters?

Loamy soil is the most fertile type of soil you can use for your garden or potted plants. It’s especially heavy soil because it combines sand, clay, and silt particles. Therefore, you’ll need a lot of soil if you’re using a large planter–increasing its overall weight as well as costs. 

Also, the weight of the soil can flatten out and compress plant roots, affecting drainage, plant health, and root development, as well as resulting in other plant-related problems. To solve these problems, experts and newbie gardeners use styrofoam.

While regular plastic and wood are great alternatives, gardeners use styrofoam because it doesn’t absorb moisture from the air. This lack of absorbency is because the material contains tiny air bubbles that allow the air to circulate easily and quickly.

Styrofoam is a superb insulator that protects plants against cold weather conditions like frost heaves and snowflakes. So, if you’re keeping a plant in an area where temperatures can get very cold or hot (like your garage or basement), styrofoam will help control the soil temperature.

As I’ve mentioned, you must consider the downsides of using styrofoam and how healthy you want your plants to be before you make any potting decision.

How Styrofoam Can Affect Potted Plants

The bottom of a planter is a part of the planter that you can’t neglect if you want to keep beautiful plants. It serves as a crucial reservoir for water, nutrients, and air. So the soil isn’t just there to hold these things in place; it’s also a food source for your plants.

However, the optimum soil type and mix can vary from plant to plant because a plant’s growth depends on several environmental factors. The factors include the soil conditions the plants are accustomed to growing and how much room they have to grow.

Of course, the soil can get too soggy, which can be a serious problem. This problem is especially severe for plants that prefer low soil moisture content. Therefore, it’s typical that many gardeners might look to materials like styrofoam to control soil moisture content and improve drainage.

So, while putting styrofoam in the bottom of your planter may seem like a good idea, it’s not worth the risk.

Now let’s see how much of an impact styrofoams can make on the growth of your plants.

How Styrofoam Can Attract Plant Pests

Styrofoam is ubiquitous, but it’s been known to attract common pests like rodents, termites, and ants. These pests don’t eat the styrofoam but tunnel into the material and make nests. These tunnels can lower the insulation properties of the foam and seriously harm your plant’s health.

Pests usually affect plants in many ways but can cause irreparable damage like growth stuntedness and root rot. As you’d expect, the affected plants typically don’t reach full maturity and might lack vegetative parts like flowers.

Pest infestation in potted plants can also lead to health issues if you’re growing edible plants. And unfortunately, it might be pretty challenging to remove the pests from your planter.

How Styrofoam Can Affect the Environment

Styrofoam is made from polystyrene, a petroleum-based plastic widely used in everyday products like utensils, plates, and cups until it was banned in the United States in 2020. Governments made many policies in different parts of the world to stop their usage, and the ban became necessary despite the ability to recycle these materials. 

You might wonder that since the petrochemicals in styrofoam make it very durable, there should have been no need to ban the material. However, several studies have shown that they contain carcinogens that pose health risks when inhaled or consumed directly by humans or animals.

But that’s not all.

Styrofoam’s lightweight structure means it’s easily blown by the wind or washed away by rain into water sources. And since styrofoam isn’t biodegradable, it can leach into the soil and pollute groundwater supplies.

Its brittleness can also be problematic. The material can break into small pieces that are easy for animals to eat, seriously harming them in the process.

What Alternatives to Styrofoam Can You Use for Planters?

Undoubtedly, styrofoam can be an excellent material for you to use during gardening, but the problems outweigh the benefits. Therefore, if you’re looking for a way to add a material that would aid the growth of your plant in your planter box, consider using a more environmentally friendly option. Many other materials are just as good and won’t cause problems for the plants or animals around them.

Here are a few alternatives to styrofoam you can use for your planters:

  • Perlite
  • Vermiculite
  • Rice Hulls

These materials might seem strange and out of place–especially if you’re an amateur gardener or plant keeper. Therefore, let’s explore what they are and how they’re better than styrofoam for planters.


Perlite is a natural product of volcanic soil and is, therefore, very porous. It contains beneficial elements for plants and serves as an excellent soil additive. It’s common to confuse perlite with styrofoam since they both share the same bubble-like appearance. 

But unlike styrofoam, perlite doesn’t contain any toxic chemicals or additives. It’s also an excellent option for perennials, seedlings, and small plants that prefer less soil moisture.

Perlite doesn’t compact and keeps the soil airy–making it easier for root systems of vegetables and flowers to spread and for their seeds to germinate.

The light color of perlite also helps prevent elevated soil temperatures. The material is available in many grades and specifications, but most types work well with all plants.

You can check out Miracle-Gro Perlite (available on if you need a superior perlite brand for your potted plants. It’s fortified with all the essential nutrients for your plants to thrive and improves drainage and aeration.

I recommend mixing 2 to 3 inches (5 to 7.6 centimeters) of perlite at the bottom of your planting container to control how much moisture reaches the roots. Alternatively, you can use large containers with more than a gallon capacity and fill them with small pea-sized pieces of perlite.

Perlite helps plants grow and stay healthy in their containers, and it’s a great way to add nutrients to your soil–especially for plants that don’t need much fertilizer or water.

If you don’t have perlite available, there are some great alternatives. Check out my other article to see which ones: 14 Best Substitutes for Perlite in Gardening


I’ve heard several people argue that vermiculite and perlite are the same material. However, they differ in their ability to retain moisture as well as in many other ways. Vermiculite is a mineral composed of feldspars and mica with minor amounts of silica, and its composition makes it lighter than perlite.

However, vermiculite still provides great soil drainage because it retains water better than perlite.

Vermiculite improves drainage by adding air pockets into the potting mix and allowing excess moisture from watering plants to escape quickly without weighing down their root systems. It’s also effective at binding soil particles together to ensure they don’t fall apart when you add them to your potting mix.

I don’t recommend using vermiculite alone or mixed with ingredients like compost or peat mosses. It’s better to blend peat moss and vermiculite for better drainage and aeration in your planter.

It’s important to note that you may need to water planters with vermiculite more often to help keep the soil moist.

Rice Hulls

Rice hulls are a byproduct of the rice milling process. They are formed from the outermost parts of each kernel, created when the bran and germ separate during germination. These hulls are an excellent addition to your gardening plans compared to styrofoam because they are less expensive and simpler to locate.

The organic hulls are used as a natural soil amendment and in mulch for gardens, owing to their high moisture content (about 90%). Rice hulls’ ability to retain moisture without compacting or drying out too quickly makes them a better option for planters. Rice hulls easily drain water from the soil because they are porous.

The material’s also light and non-reactive, which means you don’t have to worry about them damaging your plants or polluting the soil with unwanted chemicals.

Of course, they also provide additional nutrients to your garden because they hold moisture well enough to be used as an organic fertilizer. But ensure that the humidity in your air doesn’t get too high or low, as this can cause them to dry out.

Some people use bark for better drainage. Check out my article to see if it’s a good idea: Does Bark Really Work for Drainage in Pots?


Caring for your plants can be hard work, but you’ll enjoy the benefits if you do it right. The goal is for your soil not to drain poorly or too quickly because soil nutrients will leach out of your plants and into the drainage hole at an alarming rate, causing root-and-shoot problems.

The best way to prevent these problems is by using a well-draining soil mix that is safe for the plant and the environment.

Alexander Picot

Alexander Picot is the principal creator of, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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