Hey Nah,

Rich here, day three of 7 Days to Houseplant Mastery.

Quick question. Have you ever put stones, gravel or broken crocks at the bottom of a pot "for drainage"?

Most of us have. It sounds completely logical. It's also one of the most common reasons plants end up with root rot.

Here's why. Every pot, however good its drainage holes are, has a wet zone at the bottom. Gravity can only pull water so far before the soil hangs onto it, so that bottom layer stays saturated. It's called the perched water table. Add rocks and you don't get rid of the soggy layer. You just lift it higher, right up into the root zone, and shrink the space your roots have to live in. You end up with more water where the roots are and less room for them to escape it.

The fix isn't a layer. It's the mix itself.

This is also where most bagged compost lets you down. It's dense, it holds far more water than houseplants want, it packs down over time, and it sometimes comes with fungus gnat eggs as a free gift. I stopped using it as my base years ago and switched to coconut coir. It's lighter, cleaner and far more consistent. (The catch is that coir contains no nutrients at all. That matters, and it's tomorrow's email.)

Try this: find any pot with a "drainage layer" in it. That one goes first in the queue next time you repot.

In the Soil module of Houseplant Mastery, I give you my actual base mix, with the ratios. It's just three ingredients. Then I show you how I tweak it for aroids, calatheas, and cacti and succulents. One extra ingredient turns it into a calathea mix. Double up on another and it's a cactus mix. No expensive specialist bags. The Pots module covers terracotta vs plastic (I've smashed more terracotta than I'd like to admit) and how to use decorative pots without drowning anything.