New houseplant people, listen up:
- Soil is not anywhere near as important as getting the light/water correct
- Those pre-made species-specific potting mixes MIGHT work for you, but they might not
- Keep things simple
- When people refer to a ‘chunky’ soil mix, they’re talking about orchid bark/leca/pumice
What I keep in my soil ingredients arsenal
- Store-bought houseplant potting mix
- Perlite
- LECA
- Orchid bark
I have dabbled with worm castings and charcoal in the past. I personally think charcoal is a waste of time, but worm castings are great for adding nutrition. I have LOADS of coir but switched to using just store bought soil because… I’m lazy.
Any houseplant potting mix is fine. Don’t buy anything for outside plants for two reasons:
- It tends to stay too wet for too long
- There’s often compost/manure in them that can attract flies
The soil by itself is usually too dense and retains too much water. I add leca, perlite or orchid bark to increase the airflow.
Why not just use houseplant soil on its own?
It’s too dense. This is bad for two reasons:
- The soil stays wet for two long
- There isn’t enough airflow
Roots need oxygen. If your plant is in soil it will have soil roots, which can absorb oxygen from the air (like we can). If the soil is staying too wet for too long and there are no chunks to create air pockets, the roots will rot.
If your plant is established in water, it will have water roots, which can absorb oxygen from water (like a fish). Like soil, water can get deoxygenated and can also cause rot.
I do think houseplant soil is getting better, BUT it’s still cheaper to cut it with leca/perlite.
My soil recipe
You won’t go far wrong with equal parts houseplant potting mix, perlite and/or orchid bark and/or leca.
I don’t use an exact recipe. I don’t even usually mix it, I just add different ingredients in layers and then hope it mixes itself over time.
All of the quantities are determined by how much I have of any one ingredient at the time. If I find it dries out too quickly (within a couple of days, depending on season), I add more soil. If it stays wet for too long (three weeks) then I’ll add more bark/perlite.
A more ‘traditional’ houseplant soil recipe is this one, which I used to use, but don’t feel is worth the hassle:
- 5 parts coir (soak it in water then squeeze out the excess)
- 3 parts perlite
- 3 parts orchid bark
- 1 part charcoal
- 1 part worm castings
Why I don’t buy fancy plant-specific soil mixes
I don’t like these mixes, not because they’re bad, but because they’re pushing a false narrative that certain plants need specific soil mixes.
If a new plant person has an Alocasia and they put it in a soil formulated for Alocasia they mentally tick the soil box. They KNOW the plant has the right soil – it says it on the label.
But it might not suit their needs/conditions. The people who make it are making something that suits their environment. Also, they know what they’re doing.
I like the Grow Tropicals Philodendron mix because it suits my plants, care type and home environment. I don’t buy it often because it’s cheaper for me to buy houseplant mix and cut it with orchid bark and perlite. And I certainly don’t keep it for my philodendrons.
It doesn’t make enough difference to be worth the price.
It’s nice, and it’s convenient but it is NOT necessary.
How bad is the soil that comes with the plant?
Either I’ve been very lucky or it’s not as bad a people make out. I rarely repot my plants straight away and if i do I usually incorporate the old soil into the new.
My hoya bella still has a ‘plug of death’ and it grows fine. Obviously your mileage might vary but I’ve bought literally hundreds of plants and I’ve NEVER bought a plant with soil so bad i had to repot it from a nursery.
I have been given plants by friends to revive and it’s almost always in outside potting soil. Those i will repot, but tbh they’re usually so far gone I chop and prop.
Reusing soil
As I said, all my plants go into a weird frankenstein of whatever ingredients I have. I also rarely throw out soil (because wasteful) and I get surprises like this:
Yes, that is a Calathea growing in a Philodendron brasil pot.
People worry about pests in the soil but the pests I don’t want to get (mealybugs, thrips, spider mites) don’t live in the soil. Gnats are a result of providing them with a gnat-friendly environment (and as an underwater I do NOT do that).
If you don’t want to reuse soil, don’t, but I do and it’s fine.
How to tailor soil to particular plants
By and large, most houseplants will be totally fine in a very similar soil mix.
You don’t need to tailor soil to plants because you should be tailoring the light and water to the plant.
For example, Calathea need less light than hoya and like to stay consistently moist. A hoya in a bright window will dry out faster than the Calathea in a darker spot because it’s hotter and drier.
After a week or two, the Hoya might be bone dry and ready for watering. The Calathea (in the same soil) won’t be as dry but would still appreciate some water because they prefer to stay damper.
If you’re an underwaterer, add more water retentive ingredients to your soil, such as leca.
Overwaterers add more bark.
Do NOT try to replicate what is happening in the wild, substrate wise. Plants grow in a variety of substrates and conditions and appealing to nature in this way is a waste of time. Alocasia can grow in water in the wild, but they rot in the blink of an eye in hydroponics unless you’re on the more experienced side.
The only exception I have to this rule is:
- My maidenhair fern don’t get any bark or leca – they’re in perlite mixed with soil
- My orchid is kept bare root
- Succulents/cacti for most people – I keep them in the same soil but I also whack them outside at any opportunity. They need the brightest light you can offer, lots of water frequently but then dry out SUPER quickly. Professional cactus growers water daily but dry out the soil with a hair dryer.
In conclusion
Soil isn’t that big a deal IF you have the light and watering needs down. If you don’t have the light and watering needs covered, the best soil in the world won’t help.
I recently came across your blog and so appreciate it. Your writing style is creative and informative and I love the “er”s you put in. Feels like it’s a conversation.
I have some Snake plants and left over cactus/succulent mix. I’m interested in the charcoal. Would you suggest putting some of that into the succulent mix for my Snake plants too?
Thanks in advance!
Thanks so much, that means a lot!
I do put charcoal in my potting mix but I wouldn’t use it with snake plants, simply because they’re pretty disease-resilient and don’t really need it.
If you have charcoal to use up then by all means put it in, but your snake plant probs won’t care one way or the other. You might be better if saving it for a more delicate plant.
Hallo, is this good for pretty much any houseplant? I’ve a mix of cacti, succulents and actual plants and have enough to do without 14 different soils! Also, your worm cast link doesn’t work, but I found another one 🙂
Thank you, these are very funny and interesting articles (I’m reading through a bunch)
I just adjust the quantities perlite and bark to increase/decrease drainage. I use less bark for Calathea And ferns and more for epiphytes and philodendron. I do add sand to succulents, but everything else goes in broadly the same mix and I haven’t had any issues.
You can adjust the soil mix to reflect your watering habits too – if you’re an underwaterer, adding more coir will stop your plants drying out so quickly, but use less if you’re more likely to overwater.
Thanks for pointing out the link, I’ll change it!
I love this article, I got a lot of good information from it and will use it to make my own potting mix now. But we do know why it’s called pH. It stands for potential of Hydrogen–it measures the concentration of Hydrogen ions in a substance. I learned this in nursing school. :0)
Awesome – thanks for the info!
Hi i have a small monstera albo (currently 5 leaves) I am so worries about it as it was rather pricey. i noticed yesterday that on one leaf it got large dark brown splodges, mainly on the white part, but my ‘investigation’ seemed to suggest over watering :(. i have cut a couple of roots off, thankfully it wasn’t too damaged re-potted into a better growing medium and not watered it. have a done the right thing? is there more i can do, or do i need to wait.
Also it had a small infestation of spider mite that i have removed and am monitoring. Are the leaves easily damaged as it seems to get brown marks on it very easily. I feel like a terrible plant parent to this plant (please can need to point out i have lots of other plants that seem to be perfectly happy), i thought these plants were rather easy to look after but i feel mine is rather temperamental. Any help is really appreciated
The white parts do brown really easily, but because they’re dark brown I suspect you’re right about the overwatering. My rule of thumb is that I don’t start to worry unless the green parts are starting to brown.
It will take time to regrow some roots – I’d consider putting it in something that will let you easily check the roots – water, perlite, moss, or even just keeping it in potting mix but switching to a clear pot.
They are temperamental, and slower growing that green monstera, but it should be fine. I’d recommend increasing your humidity- not only will it help your plant grow faster but it’ll discourage spider mites.
If it makes you feel better, my Thai constellation is a nightmare. It had root rot, trapped leaves that need extracting (and now look super ragged) thrips…you name it. The thing that helped me the most was keeping it in my bathroom window. It liked the light, the humidity, and I could pick bugs off it whilst I was showering. It took a good few months to start producing healthy leaves, but I think I’m getting there!
Thanks so much.
A very small part of the green has a mark on it so thats a concern.
I think i need to change the growing medium as i have it in soil approx 50%, perlite about 25% and bark 25%, i done that about 3 hours ago, do you think i should get it out of that and do something else?
That mix is fine (monstera typically aren’t that picky, and perlite and bark will give plenty of aeration), but if the roots don’t look healthy I’d rehab them in water – wash off as much soil as you can so the roots can absorb as much oxygen as they can. Tap is fine, just let it sit for a few hours to bring the temperature to room temp.
Keep it in water (change every 3 days or so) until it’s grown another inch or so of roots.
If the roots look ok it’s just a waiting game. Increase light, humidity, and temperature to promote optimal growth.
The roots looked reasonable to be honest, there was maybe a centimetre of one that i trimmed to be on the safe side but it wasnt mushy. ill keep an eye on it over the next day and if it looks to be deteriorating ill follow you recommendation. Thank you so much, really appreciate it
You’re welcome – good luck!
After an extensive search for a peat-free mix, I finally came across Organic Mechanics. They have a few different blends but I am using their regular coir-based potting mix and adding ingredients as needed for certain plants. So far, so good. If you can find it in your area (their website has a search function for retailers), you should give it a try.
Ooo, thanks I’ll have a look!
There is absolutely a reason acidity /alkalinity is measured on a pH scale. pH stands for the inverse log concentration of hydrogen ions in an aqueous solution. Acidic compounds are acidic as when in solution they increase the concentration of hydrogen ions (H+) compared to hydroxl ions (OH-) compared to an equally balanced pure water solution (H2O), I. E. Sulphuric acid (H2SO4) dissolves into 2 x H+ and 1 x SO4^2- thus increasing the relative concentration of hydrogen ions in a solution and causing a lowering in the inverse log (pH).
Thanks, I’ll link to this comment in the post!
Hi there!
I found this very helpful! O have a question.
Should I measure it out with a measuring cup for all parts or should I measure it out by weight? I know that could make a big difference if it’s 5 cups of this and 4 cups of this vs 5 pounds of this and 4 pounds of this.
I honestly just eyeball it, but a measuring cup is preferable to weighing it.
I am making a bath tub size batch of potting mix. I will be substituting coconut coir for peat. Today I bought a 50 lb sack of coir for 500 prsos ($9). I am retired and live in the Dominican Republic.
I’m finding most of the ingredients for free in vacant lots and building sites close to where I live.
Would you like a report on what I’m doing? Photos?
Thanks! i don’t think a report is necessary but let us know how it goes!