Over the years of killing more indoor plants than I care to admit, I’ve learnt a lot about what NOT to do… And simply digging up soil from your back garden for houseplants is one of those lessons! Indoor plants need a good quality soil that offers both water retention and aeration for them to grow and thrive.
So what is the best soil for indoor plants? This is probably debatable and would vary depending on the plant but 95% of the time, I use the same houseplant potting mix formula — and my indoor plants LOVE IT!
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My potting mix formula
All plants prefer different conditions, such as the amount of sun, frequency of watering, and type of soil!
Most of the time though, I find this potting mix formula keeps my indoor plants — everything from succulents to ferns — happy and thriving.
50% potting mix / 25% perlite / 12.5% peat moss / 12.5% vermiculite
Or to put it simply, half potting mix, and then for the other half, I use half perlite and a quarter of peat moss and vermiculite.
Each of these added ingredients does something a little different and ultimately combined they create the ideal environment to grow.
There are plenty of bagged potting mix varieties on the market and I generally look for an all-purpose one that’s got ‘organic’ on the packet.
I find potting mix alone isn’t sufficient for my indoor plants as water runs too quickly through the soil and they aren’t able to retain enough moisture to grow. One day I was speaking with a horticulturalist who suggested adding several other ingredients…
Perlite is a lightweight volcanic glass that improves water retention, aeration and drainage. It feels a little bit like styrofoam and is best for keeping soil loose — meaning water can easily travel to the roots of your plant.
When I’m growing or repotting plants that prefer dryer soil, such as cacti or succulents, I’ll generally increase the amount of perlite I use as it tends to drain water better than vermiculite. Just be aware that too much perlite can cause fluoride burn (brown tips on houseplants) so watch out for this and adjust your soil ratio to suit that plant’s needs.
Peat moss, as the name suggests, is a type of moss that helps to retain moisture in soil. It holds moisture and releases it to your plant’s roots as needed. Peat moss also helps to protect against extreme temperature conditions so if you find your plants struggle in summer or winter, this is probably something you want to consider mixing into your soil.
The final ingredient I add to my indoor plant soil mix is vermiculite. This stuff almost feels like small wood chips and its main functions are to improve moisture retention and aeration — resulting in healthier and more robust plants.
I hope sharing my indoor plant soil mix formula helps you grow your indoor jungle. If you’ve got a different recipe for the best soil for indoor plants, I’d love you to share your tips below!