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Easy DIY potting soil mix and houseplant FAQs

Answering community indoor gardening questions | Digging in with gardenstead Ep. 11

Aaron Deacon of BIOS Nutrients is back on the pod! This time, our favourite plant and soil expert sits down with Katie to answer questions from our community about houseplants and indoor gardening.

So, if you’re looking for an easy DIY potting mix for indoor plants, are desperate to know what to do for an overwatered plant, or really want to know which is better: water or soil propagation? — this episode is for you.

Katie and Aaron also take on the ‘when to repot?’ question, whether or not you can re-use old soil, and what to do if you’ve over-fertilized (we’ve all done it, don’t worry). Plus, lots more answers are jammed into this quick-moving episode (show notes are included below).

Show notes

In this episode all about indoor gardening, Katie and Aaron cover a lot of houseplant territory as they answer questions from our growing community.

DIY soil mix for indoor plants

For succulents, cacti and some tropicals that prefer more aerated soil, Aaron’s basic recipe is simple: use a mixture of 40% regular potting mix and 60% perlite. For more moisture-loving plants like alocasias and pothos, just flip the ratio — mix 60% potting mix with 40% perlite. Aaron also shares what he calls a more advanced recipe in the episode, if you have plants that need even more well-aerated soil.

Wondering what might be a good soil mix for indoor herb gardens or if different herbs have different soil needs? This episode has the answers you’re looking for.

Is it better to propagate plants in soil or water?

Aaron takes on this possibly divisive question with ease. The short answer: depends on the plant. Many plants will do just fine propagated in water — it’s also the easier method of the two (“you just set it and forget it”, as Aaron says).

However, some plants prefer to be propagated in soil or potting mix. Sphagnum moss works well, thanks to its excellent aeration and ability to hold moisture. (Leca and pumice are great sustainable alternatives.) Check out the full discussion in the episode, starting at 4:23.

How often should you repot houseplants?

While Aaron’s not a fan of repotting houseplants unless it’s absolutely necessary, when the time does come to repot, his recommendation is to go up only to the next size (1” or 2” larger). Why? Keeping indoor plants in smaller pots helps prevent overwatering. Wondering if you can re-use potting soil from the old pot? Yes, you can — and Aaron always does.

How do you help an overwatered plant?

First, take a deep breath — you’ve got this. Aaron’s step-by-step guide isn’t just reassuring, it’s simple, too:

  • first, remove the plant from the pot
  • then, remove all the wet soil from the plant’s roots
  • it can take a long time for soil to dry, so instead of waiting, mix some dry soil with the wet in the pot to reduce the overall moisture level
  • use hydrogen peroxide or alcohol to kill harmful bacteria that may have grown in the friendly, over-watered soil
  • because hydrogen peroxide will kill all the microbes (good and bad) in the soil, add some compost or BIOS fertilizer
  • this will put biology/life back into the soil — and feed the plant’s roots to help it thrive and grow again

And, done. See? Easy.

But wait, there’s more indoor plant care

It is 18 minutes of houseplant chat, after all. Hit play on the episode to get the answers to:

  • Is there a fix for root rot in houseplants?
  • How do you prevent salt build-up in soil?
  • How do you fix salt build-up in soil?
  • What do you do if you’ve over-fertilized your plants?
  • Does banana tea work as a fertilizer?
  • Should you add crushed eggshells to soil?
  • How do you keep pets (especially cats) out of your houseplants?

Do you have a question that’s not covered in Aaron and Katie’s conversation? Share it in the comments for the episode and we’ll add it to our list of “what to ask Aaron” for the next time he’s with us. We’d love to help you out.

PS: Don’t forget to subscribe to our channel — we post new videos every week!

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