How to Make Potting Soil

Learn how to make potting soil for indoor plants keeping them thriving, especially when you repot your plants into larger planters.

I've been growing houseplants since I was a little girl. Over the years I have grown and killed many plants. One thing I have learned is that most of the time plants that didn't do well resulted from a water issue. Sometimes it wasn't even the amount of water that I used but the potting medium was holding on to too much water.

Too Much Water Kills Plants

Sure, you can lift the pot to see if it is lighter or stick your finger into the pot to check for dryness. Believe me, I've done both. I've even invested in a water meter. In the long run, the best method of keeping my plants healthy is to ensure fast drainage.

Repotting and Transplanting into New Soil

This is most important when you need to repot or transplant cuttings into a new pot. Typically I do not have a problem with houseplants from the nursery. They tend to be planted in a nice lightweight bark-like well draining mixture. In fact, I will often keep my plants in the original pot as long as possible.

The one exception is the sponge-like substance that poinsettias are grown in lately. I'm not sure what it is and I've only noticed it the last two years but I find them hard to keep alive.

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My Go-To Potting Mix Blend

It's very simple. The best and most inexpensive way to get well-draining soil for your houseplants is to combine a good potting mix with perlite. That's about it. You could try using some of your garden soil mixed with perlite but that may introduce other issues like weed seeds or pathogens you don't want.

Perlite

Perlite (volcanic rock) can be found at just about any hardware, big-box store, or nursery and it's super cheap. The one concern about working with perlite is that it's very dusty. So make sure you get it wet to cut down on the dust and consider wearing a mask.

Potting Soil

I'm old school and prefer a nice soilless mix without all the extra added stuff like fertilizers with nutrients. However, that's just about impossible to purchase today, so I look for an inexpensive one that's made for indoor plants and go from there. One thing I do steer away from is the potting soil that has added water-absorbing crystals or particles.

How Much Perlite to Use

When combining potting soil and perlite I use a 3:1 ratio or a 3:2 ratio for succulents and other plants that like a very dry environment.

Make sure that you always use a pot with a drainage hole. Making your own potting mix and using it in a pot without a hole is a waste.

Also, it's a good idea to leave a little room at the top of the pot for watering. This way the soil will not come splashing out when you water. This aloe was potted with a 3:2 ratio of potting soil to perlite to keep it extra dry. Something I do for all cacti and succulents.

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Some people do not like the look of perlite. You could use something like this Pine Bark Fines. However, it is much more expensive and the pine is acidic. Still, if you like the look you could just top-dress the pot with it or pretty gravel.

Here's a Rabbit's Foot Fern that was outgrowing its pot. I used the 3:1 mix for this plant because ferns like a little extra moisture.

The pot I used was only a little larger and that seems to work best for repotting. If you move to too large of a pot there will be too much extra soil. Even with a well draining soil, the roots will not be able to utilize the water causing soggy soil and possible root rot.

The simple addition of perlite to a basic indoor potting mix is an easy, inexpensive way to treat your houseplants to a welcoming environment in which they can thrive.