What Soil To Use For Indoor Plants

If you’re new to repotting houseplants, choosing the right soil mix can be a bit of a minefield – who knew there were so many different types of dirt, right?

Why the Right Potting Soil Mix is Important

Plants grow best in their natural habitat. Obviously, the living room or bathroom isn’t a natural place for a plant to grow. By mimicking the plant’s natural surroundings, we can help plants for the home flourish. 

Along with the amount of sun and moisture a plant receives, getting the right soil mix is integral to keeping potted plants healthy and happy. High-quality soil is essential for providing plants with vital nutrients. The closer the potting mix is to that of the plant’s natural habitat, the more likely the plant is to thrive inside the home.

The Best Potting Soil For Indoor Plants

A general potting mix is fine, and provides enough organic nutrients for most indoor plants.

As a rule of the thumb, choose a well-draining potting mix for indoor plants. Doing this helps prevent the soil from retaining too much moisture and keeps the plant’s roots from developing root rot (which is never good!)

How Often to Replace Soil in Houseplants

It’s worth noting that the nutritional value of soil depletes over time, meaning that soil needs to be changed every so often. Most plants won’t need repotted every year. Usually every 2-3 years is sufficient. Whenever you repot a plant to offer it more room to grow, use new soil for planting. Doing this keeps the valuable nutrients within easy reach. Fresh soil also helps solve water retention issues, improves airflow and aids drainage.

Outdoor Soil and Indoor Soil

Anyone new to plant parenthood would be forgiven for thinking that soil is just soil and that any old bag will do. However, the differences between garden soil and indoor potting soil mixes are significant.

The main difference is that potting mixes for indoor plants are designed to aid drainage and afford aeration. Indoor potting mix ingredients usually include materials like perlite and pine bark to help keep the soil light. Garden soil isn’t generally suitable for indoor gardening because it is dense and gets compacted easily, leading to problems with root rot.

Types Of Potting Soil for Indoor Plants

While regular potting soil is suitable for most houseplants, some plants grow better in specific potting mixes.

Cacti and Succulents

Native to hot, dry parts of the world, cactus and succulent plants hate having ‘wet feet’ from overly damp soil. For this reason, they need well-draining mix to help keep the root system relatively dry. A high-quality cactus mix or succulent mix contains gritty ingredients such as sand and perlite to ensure the soil dries out in just a couple of days, replicating the plant’s natural habitat. As many succulents and cacti plants hold water in their leaves, they don’t need watered whenever the potting mix dries out.

Flowers

Flowering plants use lots of energy to produce a show of blooms, so they need a potting mix that provides plenty of nutrients. Most potting mixes suitable for these thirsty plants hold moisture without becoming waterlogged. They aren’t as free-draining as a cactus mix and usually contain lots of organic material for nutrition.

Tropical Plants

Many tropical plants, such as kentia palms and prayer plants, benefit from a chunky, well-draining potting mix high in organic matter. Generally, a slightly acidic soil pH is best for growing tropical indoor plants.

Orchids

If you’ve ever examined an orchid’s root system, you’ll know that they need an airy potting mix with plenty of room for the roots to breathe. The ideal orchid soil mixture contains porous materials such as sphagnum moss and coco coir to ensure the roots don’t suffocate.

Creating Your Own Potting Mixes

Shop-bought potting mixes are perfectly adequate for growing indoor plants. However, you know your plants better than anyone else. Creating your own mix ensures your specific plant gets everything it needs from the potting soil. If you’re not confident enough to start from scratch, consider adding some materials to your existing mix to make different soil blends for each plant.

The Best Soil Additives for Indoor Plants

Worm Castings

If you’re looking to add beneficial microorganisms to your potting mix for healthy plants, you can’t go far wrong with worm castings. Indoor plants don’t benefit from worms wriggling around in the soil in the same way as outdoor plants do. However, you can buy worm castings in a bag to mix with indoor potting soil. Earthworm castings are basically worm poop, so they act as a manure offering plenty of beneficial microbes to fertilise the soil.

Sphagnum Peat Moss

Sphagnum moss and peat moss are two parts of the same plant. Until relatively recently, it was widely used to create light, airy potting mixes offering excellent water retention while allowing plenty of air to circulate the roots. However, peat moss is environmentally problematic. Due to its extremely slow-growing rate, peat moss is an unsustainable additive that is being phased out in soil compositions.

Coconut Coir

Coconut coir, or coco coir, is the perfect replacement for sphagnum moss and peat moss, and is much more sustainable to harvest. It is made from shredded coconut husks, so it retains moisture without getting heavy and water-logged. Coconut coir is an ideal additive for promoting airflow and producing a well-draining soil mix.

Perlite

You know those little white ‘bits’ found in potting mixes? Those are perlite, a naturally forming glass-like substance perfect for improving drainage in potting mix. Perlite helps keep the soil loose and free-draining, which is ideal for plants like succulents. Use less perlite in the mixture for moisture-loving plants.

Sand

Adding sand to drought-tolerant plants like cacti is a great way to encourage free-flowing drainage. Sandy soil replicates these plants’ natural habitats, which is the aim of creating your own potting mix.