A reader asked whether the standard chunky aroid mix is right for Alocasia. Short answer, no. Longer answer, the recipe isn't wrong so much as it was written for a different plant and then handed to this one because both happen to be aroids. That's a family word covering 118 genera, and it hides the one difference that decides everything about substrate: some of these plants climb trees, and Alocasia doesn't.
A family word doing a genus job
Search for Alocasia substrate advice and you'll land on the same recipe every time: bark, perlite, charcoal, maybe some coco chips, all of it coarse enough to rattle. It's called a chunky aroid mix, and the logic behind the name is that Alocasia is an aroid, so the aroid mix must be the one.
Araceae is a family of roughly 118 genera and more than 3,800 species. It holds floating pond plants, bog plants, desert-edge plants, forest-floor plants, and vines that spend most of their lives high in the canopy. Knowing something is an aroid tells you almost nothing about how it grows, which means it can't tell you much about what to pot it in either.
The chunky mix works. It just works for a different set of plants than the ones it usually gets applied to.
Where Alocasia actually grows
The genus runs from Southeast Asia out through the Malesian islands and into Australia (Nauheimer et al., 2012). Across that whole range it lives on the shaded forest floor, rooting into leaf litter and humus, sometimes onto rock where humus has caught in the cracks. These are understorey geophytes: the plant's core is a corm at or just under the surface, with fibrous roots running out from it.
Look at what that material actually is. Leaf litter and humus are fine-textured, they hold water, and they stay damp under a closed canopy where very little sun reaches the ground. Nothing in that description is coarse, fast-draining or mostly air.
One number is worth flagging. Nauheimer and colleagues described Alocasia as comprising over 113 species in 2012, and that figure gets repeated everywhere, including by us. Kew's current backbone lists 91 accepted species (POWO, 2026). Nobody erred: taxonomists have folded names together in the years since, which is why a species count should carry the year it came from.
What the climbers are doing instead
Now the plants the chunky mix was designed for. Monstera, Epipremnum, Philodendron and Syngonium germinate on the ground and then climb, holding onto trunks with roots that emerge along the stem. These are usually called secondary hemiepiphytes, though the category is contested enough that Zotz (2013) argues the term should be retired in favour of "nomadic vine." That's an argument about naming. The climbing itself isn't in dispute, and the climbing is what matters here.
Those roots are built for a job. In Syngonium, the attachment system involves root hairs that release a mucilaginous substance and then deform into helical ribbons, which the authors interpret as energy-dissipating units (Yang & Deng, 2017). The paper describes them the way you'd describe a cable: load, dissipation, failure.
They also change as they leave the ground. In the aroid vine Rhodospatha oblongata, roots exposed to open air replace their epidermis, exodermis and outer cortex with an inner layer of lignified cork (Filartiga et al., 2021). The plant rebuilds the root for open air as it climbs.
So a mix designed around bark and big air gaps is answering a genuine question: what do you give a root that evolved to grip a tree and live in moving air? That question doesn't come up for Alocasia. Its roots are in the litter layer and they stay there.
What coarse particles cost you
The mismatch isn't only academic. Coarse particles cost you something specific.
Two properties decide how a potting substrate behaves. Air space is the share of the pot filled with air once it's been watered and allowed to drain. Available water is the share holding water the roots can actually pull out, as opposed to water bound so tightly it may as well not be there.
They trade against each other, and particle size is the dial. Bilderback and colleagues (2005) compared fresh coarse pine bark against the same bark aged a year. The fresh, coarser material came in near 40 percent air space with under 10 percent available water. The aged, finer material ran closer to 25 percent air space and 26 percent available water. Same ingredient, roughly two and a half times the drinkable water, because the particles had broken down.
For scale, the working ranges those authors measure against are 10 to 30 percent air space and 25 to 35 percent available water. Fresh coarse bark lands above the range on one and well below it on the other, and their conclusion about a substrate in that condition is that it would require frequent irrigation with small quantities of water.
Frequent irrigation in small quantities describes a nursery bench on a timer. It does not describe a living room.
The trade nobody names
Chunky mix is not a drainage upgrade. It's a trade. You buy a wide margin against overwatering, and you pay for it in watering frequency.
That's an excellent trade on a nursery bench with irrigation running daily, or for a grower who waters heavily and often and has lost plants to overwatering before. It's a poor trade for a plant kept in a living room and watered when someone remembers, roughly weekly.
Run the numbers together and the reputation starts to make sense. If a substrate holds under 10 percent available water, and you water it weekly, the pot is running near empty for a meaningful stretch of every week. That's a substrate problem before it's ever a plant problem, and the schedule it quietly demands is not the one anybody was told about.
Mixes don't hold still
A bark-based mix is also not the same mix a year later.
The same study tracked one substrate, a fresh bark and sand blend, across a production cycle. At 56 days it measured 36 percent air space and 16 percent available water. At 336 days, the same pots read 25 percent air and 22 percent available water. The particles broke down, the pore structure closed up, and the numbers walked toward the middle of the working range. That drift runs in a direction you'd mostly welcome. It also means the recipe you followed describes the pot you mixed, not the pot a year later.
If a plant that was fine last year is unhappy now and nothing in your care changed, consider that the substrate changed underneath it.
What to do instead
No proportions here, because the right ones depend on your light, your pot and how often you water.
Read the roots, not the family name
Tip the plant out and look. A corm with fibrous roots running off it is a forest-floor plant, whatever the bag says. Thick roots that were clearly reaching for something to grab are the plant the chunky recipe was written for. This takes about ten seconds and settles the question better than any label.
Match the mix to how often you actually water
An open, coarse mix isn't better or worse in the abstract. It commits you to a shorter interval. Be honest about the interval you actually keep, then choose a substrate that survives it. Adjusting a recipe is easier than adjusting a habit.
Move toward finer, and take your air from minerals
If your Alocasia sits in something coarse and sulks between waterings, the direction of travel is a finer particle fraction and more water held where roots can reach it, with the aeration coming from mineral components rather than from large gaps between bark chunks. Pumice and perlite hold open pore space without the fast-drying behaviour of coarse bark, and they don't break down on you the way bark does.
Finer is a direction, though, not a destination. Push it far enough and you reach the opposite failure: dense fine peat that packs down into a solid block, holds plenty of water and very little air, and leaves the roots circling a brick. Both errors leave the plant short. One is short of water, the other short of air, and the mineral fraction is what keeps you off either edge.
The Guild's daily-driver for this genus is Standard Mineral Mix v5, and if you'd rather build your own, Designing a Mix walks through how the ratios get set and how to move them for your own conditions.
The pot is part of the substrate
Air space and water-holding belong to the substrate and the container together, not the mix alone. A short wide pot holds proportionally more water around the roots than a tall narrow one filled with the identical blend. If a mix behaves differently for you than it does for someone else, the pot is one of the first places to look.
The short version
Alocasia isn't difficult. It's an understorey plant that got handed a recipe written for a vine. Give it something closer to the forest floor it came from and most of the trouble goes with the bark.
Sources
- Bilderback, T. E., Warren, S. L., Owen, J. S., Jr., & Albano, J. P. (2005). Healthy substrates need physicals too! HortTechnology, 15(4), 747–751.
- Filartiga, A. L., Mantuano, D., Vieira, R. C., De Toni, K. L. G., Vasques, G. M., & Mantovani, A. (2021). Root morphophysiology changes during the habitat transition from soil to canopy of the aroid vine Rhodospatha oblongata. Annals of Botany, 127(3), 347–360. https://doi.org/10.1093/aob/mcaa182
- Nauheimer, L., Boyce, P. C., & Renner, S. S. (2012). Giant taro and its relatives: A phylogeny of the large genus Alocasia (Araceae) sheds light on Miocene floristic exchange in the Malesian region. Molecular Phylogenetics and Evolution, 63(1), 43–51. https://doi.org/10.1016/j.ympev.2011.12.011
- Plants of the World Online. (2026). Alocasia (Schott) G.Don. Royal Botanic Gardens, Kew. https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:1078078-2
- Yang, X., & Deng, W. (2017). Morphological and structural characterization of the attachment system in aerial roots of Syngonium podophyllum. Planta, 245(3), 507–521. https://doi.org/10.1007/s00425-016-2621-4
