In a previous post, we talked about the best potting mix for your Pilea and we gave you a few tips on how to make sure your plant gets the right combination of nutrients and structural support when it’s planted in an indoor container.
We thought we should take it a step further and help our plant-loving readers make their own potting mix for Pileas. Soil preparation is a fundamental factor when it comes to growing healthy and thriving houseplants. And we’re here to demystify all the confusing terms you may have read about online.
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What is the perfect potting mix for your Pilea? You’re not going to like this, but the answer is: it depends. Your watering schedule, the light in your indoor environment, and the type of container you use all play a role in influencing what type of soil your plant needs. But for the purpose of simplifying this task, here are the main characteristics of good soil that you should aim for.
A healthy and effective potting mix for indoor plants should:
Be tight enough to hold moisture and nutrients around your plant's roots. This is essential for plant health and growth.
Be loose enough to allow root aeration. Plant roots need to breathe, just like leaves do, and compacted soil will inhibit this process.
Be tight enough to provide good root anchorage.
Be loose enough to allow water drainage. If the mix stays too wet for too long, this may lead to root rot and the inevitable death of your plant.
Now that you know the basics, let’s see what ingredients we need to make the best potting mix for Pilea plants
There are two ways to go about this, depending on your budget and the materials that you have access to: peat-based potting mix and peat-free potting mix.
Peat-based potting mix
Peat is a brown material (similar to soil) that is harvested from peat bogs. It is the product of vegetation that has been decaying for thousands of years. It provides a good growing medium, but it’s also quite acidic, so you can’t use it by itself, especially in containers.
Peat moss, also known as sphagnum peat moss, is a form of peat that has been created from the breakdown of the sphagnum moss. Most commercial potting mixes contain peat moss because of its beneficial properties: it improves drainage, water retention and air circulation. It is also lightweight and affordable.
However, using peat moss is not at all sustainable. It is currently harvested at unsustainable rates from peat bogs by scraping off the top layer of living moss to get to the decomposed peat below. Peat bogs act as carbon sequestration areas, and are home to rich flora and fauna ecosystems (that are destroyed during peat harvesting). They also help control flooding by acting as water retention reservoirs during heavy periods of rain. That’s why there is a push from conservationists in the horticulture industry to move away from peat-based potting mixes.
The main advantage of using peat moss is its low cost and availability. The mix we usually use with our Pilea plants is coco peat fiber or peat moss, and a small portion of perlite (one part perlite to nine parts soil).
Peat-free potting mix
Peat-free potting mixes contain a mixture of composted bark, coconut coir, wood fiber and green compost. These options are then mixed with inorganic materials such as sand, perlite, or rice husk (also known as rice hulls). In order for the potting mix to be effective, you need to create a blend of fine and coarse particles that can hold enough water and air (both essential for root development). The formula for peat-free potting mix looks roughly like this:
1 part organic matter - sterilized compost mixed with pine bark or wood fiber, for example (for nutrients and moisture retention)
1 part coconut coir
1 part rice hulls, perlite, or vermiculite (for aeration)
Here are a few more details you should know about these peat alternatives:
Coco coir is the outer husk of the coconut, and it’s often a by-product of the coconut processing industry. When you order it online, it comes in the shape of sheets or bricks. Before you use coco coir for your Pilea potting mix, you have to break it apart. You can do this as soon as you get it, of course, but our recommendation is to soak it in water overnight. This makes the process less dusty and since the coir is already soaked, it won’t absorb too much water when you first water your plant after repotting. If you use it in your potting mix, keep it under twenty percent of the total as coco coir does not contain any nutrients.
A good label to look for on coconut coir is OMRI (The Organic Materials Review Institute). This means that the product is organic and has not been sprayed with any harmful pesticides.
Rice hulls (or rice husks) are the protective coverings of rice grains, and a by-product of the rice-processing industry. They’re used in horticulture to add body to potting soil because of their lightweight and stable properties.
Organic materials (composted wood fiber, pine bark, sawdust, paper waste, straw waste) are already widely used in mixes, but you can’t just use one of them. Ideally, you should use a mix of organic materials, as they each have different water- and nutrient-retention profiles.
Perlite looks like tiny white foam pellets. In fact, it is heat-puffed volcanic glass, and it’s often included in bags of potting mix to help keep it light and prevent it from becoming compacted. Perlite itself does not contain any nutrients, so it’s best to keep it under twenty percent of your potting mix.
If you’re worried about environmental impact, you should know that perlite is a mined resource, so it comes at an environmental cost. Rice hulls are a more sustainable alternative to perlite.
We think investing in environmentally-friendly potting mixes is worth it in the long run. And if you order these supplies online, you may find them in larger quantities and get a better deal.
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