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ABG soil mix is NOT for everyone. It’s mainly used in terrariums and a lot of people don’t find it chunky enough for house plants but I LOVE it. I have a lot of houseplants, but I’m definitely an underwaterer rather an overwaterer.
What is ABG soil mix?
ABG mix was developed at (or for) the Atlanta Botanical Garden, and it’s a common mix used in terrariums and vivariums. It’s decently chunky, has good drainage, and retains a decent amount of water without being soggy.
We get ours from eBay, but you can get it from Amazon too. It’s a recipe rather than a brand, so there are tonnes to choose from.
How do you make ABG soil mix?
2 parts tree fern fiber
1 part peat moss
1 part sphagnum moss
1 part charcoal
2 parts orchid bark
As you can see no perlite, which is why a lot of house plant people like it. People with vivarium don’t use perlite because it can be choking hazard to frogs and lizards.
There is a LOT of debate on the sustainability of some of these products. As far as I’m aware, unless you’re growing in straight coir (and even that ain’t great when it comes to being ethically produced) most of the products used in house plant soil aren’t particularly sustainable.
Sphagnum has the potential to be sustainable but peat moss doesn’t. Sphagnum grows on top of the peat moss layer. As long as the peat moss isn’t disturbed you can just harvest the sphagnum and it’ll regrow quickly. Peat moss, er, doesn’t. It takes a long time to form.
If you don’t feel comfortable using peat moss, you can sub in coir. Tree fern fiber went from being the darling of the vivarium industry due to it’s sustainability to being a bit of a shifty figure. For every person claiming it’s sustainable there’s another saying it isn’t.
If all of this is a no go for you, then I recommend switching to leca. At least it lasts indefinitely.
I try to buy sustainably sourced products (most of the stuff from New Zealand claims to be) but it’s almost impossible to judge what’s sustainable and what isn’t.
There are a couple of things I do to make my ABG mix go further:
- Cut it with leca. As much as 50:50
- Reuse it
- Use as little as possible – don’t put your plants in pots that are unnecessarily big.
I have a lot of plants and I’d go through an unreasonable amount of soil if I didn’t reuse it. I’m pretty tight so I don’t buy soil if I can help it.
Advantages of ABG soil mix
It’s got great drainage
This just means that water can move through it well. Some of it gets absorbed, and some of it doesn’t. If a soil mix has bad drainage, it forms mud and all clags together. ABG mix doesn’t do that BUT the drainage isn’t so good that the roots don’t get a chance to absorb the water.
It retains water evenly
Sometimes we forget that most plants actually need the soil to stay wet for a bit. Sure, if it’s wet for too long we get rot, but also, the plants do need water to live. ABG mix stays damp for a lot longer than soil mixes with perlite in my experience.
It lasts a long time
Coir is a common alternative to moss and tree fern fiber, but it doesn’t last very long. Over time its ability to retain water diminishes and it becomes hydrophobic pretty quickly.
It’s pretty neutral in terms of nutrition, but it retains added nutrients well
This is also due to the use of moss over coir. I have no idea what the science is here, but the reason ABG mix is preferable to coir mixes for a lot of house plant people is that moss is better at hanging onto nutrients.
Honestly, I have no idea how they measure this. Or if they measured it all. Perhaps the guy that developed it made it up.
It doesn’t compact easily – probably due to the lack of coir
This is true, and it’s one of the main reasons I like it. Old soil tends to get compacted very easily, and there comes a point when you can’t use it. This doesn’t seem to happen with ABG mix. The fluffiness of it lasts for years.
Disadvantages of ABG soil mix
- Not sustainable (I’m pretty sure LECA is your only option for properly sustainable house plant potting mixes
- Not suitable for plants that like to dry out quickly like succulents. However, other plants that prefer to be a little drier, such as hoya, have faired really well in it.
- It’s quite pricey. My boyfriend buys two packs a year for his terrarium, and gives me one. Otherwise, I’d probably struggle on with leca. It’s around £15 for about 30 litres which isn’t bad.
- It will NOT suit overwaterers – it’s almost like the wetter it gets, the more water it retains.
Who would ABG suit?
I love it because I tend to underwater my plants, and it stays moist for a long time whilst staying aerated.
If you like building terrariums, it’s pretty much the gold standard of soil.
If you go away a lot – travelling for work or going on vacation, ABG mix retains water really well whilst being pretty chunky, so it’s a really great option.
I’ve said this already, but I recommend staying away if you overwater. It’s also not particularly suitable for people that prefer to bottom water, because it can end up taking in too much water. I bottom watered my verrucosum and ended up having to squeeze excess water out with my hands.
If you live somewhere very hot and dry, this might be a lifesaver.
I always end up wrapping myself in circles when it comes to discussing soil because there is SO MUCH work to be done in this area of house plant care.
The fact is, this soil is awesome but probably unsustainable. Other soils are fine, but not as good, but also unsustainable. It’s not ideal!
I’m gonna do some research on sustainable soils, and synthetic mosses and stuff and see what comes up. There are plastic alternatives to some ingredients, but it’s difficult to work out if they’re actually sustainable, or just as unsustainable in a different way.