Like us, plants come in a wide variety of features, likes, and dislikes. They also know too well what works for them and what doesn’t.
This certainly applies to their soil preferences.
The hurdle for many of us is choosing the right type of soil for indoor plants when there are so many to choose from. Yet, while picking up the ‘all-purpose’ soil mixture at your local garden center may seem tempting, it can end up doing more harm than good.
So, we’re here to help you break down the types of soil in general but today, we’re focusing mainly on what works best for houseplants.
Let’s dive in!
Soil for Indoor Houseplants vs. Outdoor Plants
The best soil for houseplants is one specially made to meet the demands of indoor plants. You can’t just grab a few handfuls of soil from your yard and call it a day.
The problem with garden soil, or topsoil, is that it’s too compact and heavy for potted plants, particularly those growing indoors.
So, while garden soil may be fine for outdoor plants that aren’t restricted to a pot or container, it’ll eventually suffocate the roots and kill your houseplants.
The alternative is to get a potting mix made for indoor plants. Luckily, you can easily find a soil mix specially formulated for the type of houseplant you’re growing.
There are also more generic mixes, such as pothos. Yet, these work better with hardier, more forgiving indoor plants like snake plants, Chinese evergreens, and the African spear plant.
Another factor each type soil for indoor plants must have is proper drainage and aeration. That’s why you’ll often see lightweight, loose ingredients in indoor potting mixes, including vermiculite, peat moss, or perlite.
What Is a Good Potting Mix?
Various characteristics go into the making of a good potting mix. Yet, the most critical has to be whether the soil is alkaline or acidic, also known as the soil pH.
The soil pH is the measure of whether it’s alkaline or acidic. It’s measured on a scale of 0 to 14, where 7 is neutral. Anything less than 7 is acidic, whereas anything over 7 is alkaline.
If the soil is too acidic, it can prevent the root system from absorbing nutrients. In other words, if you’re adding fertilizer to a type of soil that doesn’t have proper pH levels for your plants, then those plants won’t be able to get any of their food.
Porosity is another major factor. This is the amount of space between soil particulates where the roots can access oxygen, also known as air pockets.
Types of Soil for Houseplants
Nearly all types of soil for indoor plants should consist of one, or a combination, of the following.
Peat Moss
Peat moss, also referred to as ‘sphagnum’ peat moss, is the layer of decaying sphagnum found in the soil. It may look like regular dirt, but it comes with many advantages.
For starters, gardeners use it to improve water retention and soil aeration. Plus, it boosts the nutrient uptake of root systems while balancing the microorganisms found in the soil.
Also, peat moss has a pH of about 4.0, which is highly acidic. Thus, it’s used to lower pH levels in naturally alkaline soil compounds like desert soils and clay.
Unfortunately, to harvest peat moss, the peat bogs are sometimes completely destroyed, which can harm the environment. As a result, gardeners are constantly searching for sustainably-harvested alternatives like coconut coir and hydrafiber.
Potting Soil
Potting soil refers to the blend made by combining actual dirt with other soil-less ingredients like sphagnum peat moss, perlite, or vermiculite.
It’s denser than other types of soil on this list. Thus, it’s more likely to retain moisture, which will ultimately result in the soil becoming weighed down, waterlogged, and not well aerated.
Consequently, this will cause the root system to become compacted and susceptible to root rot and other diseases.
Therefore, it’s recommended for use with outdoor plants rather than their indoor counterparts.
Potting Mix
Potting mixes cater to plants growing in pots or containers. Its light, fluffy texture boosts the soil’s ability to drain water and increase aeration.
This is how it prevents the soil from getting too dense or waterlogged. Hence, the root system can do its job of absorbing nutrients and moisture with ease.
Here’s a complete list of potting mix ingredients so you can mix and match to your heart’s content:
- Vermiculite
- Peat moss
- Sand
- Coconut fiber
- Hydrafiber, aka ‘wood fiber’
- Perlite
- Pumice
Perlite
Perlite is the white specks in the soil mix that resemble small pieces of styrofoam. It’s ideally suited for aiding in proper soil drainage because one of its key features is that it holds little moisture.
We have to mention that, even though perlite does a terrific job of aerating the soil, many garden centers and horticulturists are choosing to use less and less of it in their potting mixes for the following reasons:
- Perlite is a mined non-renewable resource
- It’s not sustainable and has been linked to harming the environment
- Using it creates dust clouds that cause numerous respiratory and other health problems
- Costs more to manufacture than other soil-less ingredients like hydrafiber
Sand
Adding sand to indoor plants is a great way to boost aeration and break up heavy soils. It’s also reusable and doesn’t cost much.
Yet, the main reason why indoor gardeners add sand to the soil is that it does a fantastic job of soil drainage. Plus, it has zero absorption capacity, so you can rest assured that none of the root systems will get compacted or waterlogged.
The best type of sand for indoor plants consists of coarse grains. Fine, smooth particles can actually inhibit aeration and drainage, which is the opposite of what your houseplants need.
Dirt
Dirt is basically outdoor garden soil. We don’t recommend using dirt for indoor plants for three reasons:
- Has high water retention, which doesn’t fare well with potted plants
- Lacks soil-less ingredients that boost aeration and the nutrient content of the soil
- Heavier than potting mixes, so air can’t travel between the roots and soil particles
What Is the Best Potting Mix Formula?
Experts recommend that the best potting formula for indoor plants is made up of about 70% peat moss. The other 30% should be a combination of soil-less ingredients like vermiculite, perlite, or coconut/wood fiber.
Almost all indoor plants find this mix the perfect medium for growing and developing. Then, to boost their growth even further, you can always add fertilizer during their growing seasons.
How Can I Make My Own Potting Mix for Indoor Plants?
The great thing about potting mixes is that they contain basic ingredients that you can find at any garden center. So, using the ingredients above, make a list of what you need then start mixing your own soil blend at home.
For most common houseplants, we recommend using a combination of peat moss and coconut fiber. Since most plants thrive in slightly acidic to neutral soil, that mixture will provide them with a perfectly balanced, nutrient-rich medium.
Although, if you have a cactus or succulent, you’ll need something with more aeration. Hence, we recommend you add some pumice or sand to the mix. This combination will help make it looser and lighter, and even allow for better drainage.
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How to Have the Right Soil PH Level for Your House Plant?
As mentioned earlier, having the right soil pH level is crucial for plant health. Otherwise, your plants won’t be able to take in the nutrients they need from the soil, which will cause them to wilt and wither away.
Even though each indoor houseplant plant may have different pH needs, the majority thrive in slightly acidic to neutral soil. On the pH scale, this can be anywhere between 6.0 and 7.5.
The good news is that you can adjust the soil pH accordingly to your plants’ needs. The first thing you’ll need is to get a home soil test kit or a soil pH meter.
Then, once you find out the pH of your soil, you can regulate it using a few basic ingredients.
For example, if the pH levels are too high, or alkaline, you can add sulfur to the soil. It’ll help balance out the alkalinity, reduce the pH, and make the growing medium closer to being in the slightly acidic to neutral range.
Alternatively, if the soil pH is too acidic and your plants prefer their soil to be more alkaline, add some powdered limestone. Since lime is highly alkaline, it does a great job of increasing pH levels.
Final Thoughts
It’s never been easier to buy plants on or offline. The challenge, now, is keeping them alive. That’s why knowing the types of soil for indoor plants is so vital.
Remember that choosing the right soil has a significant impact on your plants’ long-term well-being and development.
Use our handy guide to help you decide on the right one that will keep your plants healthy and happy. Then sit back and enjoy the fruits of your labor!