Aroid Soil Mix: The Exact Recipe for Monstera and Philodendron

After two years of killing aroids in standard potting mix and then methodically testing DIY substrates, I landed on a four-ingredient mix that drains in under five seconds and has kept every philodendron, monstera, and anthurium I own alive through two full growing seasons. The recipe is simple, the ingredients are all on Amazon, and it costs less per pot than any commercial "aroid mix" on the market.

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What aroids actually need from soil

Aroids — the family that includes monsteras, philodendrons, anthuriums, pothos, and alocasias — are hemiepiphytes in nature. They germinate in leaf litter and then climb trees, eventually rooting into crevices of bark, trapped organic debris, and the air itself via aerial roots. Per the University of Florida IFAS Extension on tropical foliage, aroid roots evolved for high-oxygen environments with irregular wetting and near-complete drying between rains.

That biology matters for what you put them in:

1. Drainage above everything else. Water should run through the pot in seconds, not pool. A probe-test moisture reading dropping from "wet" to "dry" should take two to four days in active growth conditions, not seven to ten.
2. Air pockets at root depth. Chunky materials — orchid bark, perlite, coarse lava rock — create the air channels that aroid roots thrive in. Dense peat-based mixes suffocate roots even when drainage looks adequate from the surface.
3. Modest, slow-release organic nutrition. A small proportion of worm castings or compost feeds the plant between liquid fertilizer applications. Too much organic matter traps moisture and compacts within months.
4. Slightly acidic pH. UConn's soil pH database lists most aroids in the 5.0–6.5 range. The DIY mix below falls in that range out of the bucket.

Standard Miracle-Gro Indoor Potting Mix fails all four criteria within three to six months. It starts fine — the moisture runs through the freshly-opened peat — and then the peat compacts into something closer to clay. At that point every watering pools around the roots instead of draining, and root rot is only a matter of time.

The DIY recipe (what I actually use)

This is the mix I make for every aroid I own. I've been using it across heartleaf philodendron, monstera deliciosa, anthurium, and golden pothos for over two years with consistent results.

Ingredients

1. Plantonix Coco Bliss Coco Coir — the base

Plantonix Coco Bliss ships as 650g compressed bricks (20-pack). One brick hydrates to roughly 8–10 quarts of loose coir. For a batch of aroid mix you'll use about a quarter to half a brick depending on pot count. The bricks store indefinitely sealed, so the 20-pack is genuinely a 1–2 year supply for most apartment collections.

One important preparation step: rinse the hydrated coir once before using. Coco coir can ship slightly alkaline from the processing facility, and a single rinse with clean water brings it down to the neutral-to-slightly-acidic range you want. Squeeze out excess water before mixing — the final texture should hold its shape briefly when compressed, then crumble.

2. Better-Gro Special Orchid Mix — the chunky bark component

One note on using Better-Gro straight from the bag without amendment: it works well for aroids, but I find it benefits from adding a bit more perlite (roughly 20%) and a handful of worm castings. The stock mix leans heavy on bark relative to organic matter, which is great for drainage but leaves the plant slightly nutrient-deficient between fertilizing sessions. If you're going to fertilize every two to three waterings with a balanced liquid fertilizer, straight Better-Gro is an excellent time-saver.

The 8-quart bag typically repots two to three mid-size aroids depending on pot size. At the current price point it's the most economical store-bought option I've found for aroid work.

3. Espoma Organic Perlite — aeration and drainage

Espoma's PR8 (8-quart bag) is the standard size for home use and lasts a long time. The bags can be dusty — I open them outside or wear a cheap dust mask when measuring, as inhaling perlite dust is irritating to the lungs.

A note on alternatives: coarse perlite (sometimes labeled "horticultural perlite" or "#4 perlite") creates larger air channels than fine perlite and is preferable for mature aroids. Espoma's 8qt product is horticultural grade and appropriate for this use. The fine perlite sold in some garden centers is for seed starting and creates less aeration than you need in an aroid mix.

4. Wiggle Worm Worm Castings — the organic fraction

Wiggle Worm is the brand that comes up consistently in r/houseplants and r/aroids as the standard recommendation. The 30lb bag is bulk — most apartment collections use 1–2 cups per potting session, so this supply lasts one to two years easily. Store it sealed to prevent it from drying out or attracting fungus gnats.

The mix ratio

For a standard 4-quart batch (enough for one 6-inch pot or two 4-inch pots):

Mix dry ingredients in a 5-gallon bucket first, then add water until the mix is barely damp. The final texture test: squeeze a handful firmly. It should hold its shape for one second, then crumble apart when you open your hand. If water drips out, it's too wet — let it sit open for 30 minutes and mix again.

For larger aroids (10-inch+ pots, mature monsteras), I increase the bark fraction slightly to 35% and reduce coir to 35%. Larger root systems benefit from the extra air channels that come with chunkier bark.

How I tested this

I want to be honest about methodology. I haven't run a blinded randomized trial comparing these substrates — I'm a home grower, not a researcher. What I have done is:

• Killed roughly a dozen aroids in standard Miracle-Gro over my first year of plant ownership
• Repotted a monstera, two philodendrons, and an anthurium into this DIY mix in spring 2024
• Tracked root health at each subsequent repotting
• Read the substrate science from University of Florida IFAS, the RHS's guidance on potting media for tropical aroids, and the NC State Extension Plant Toolbox

All four plants are alive two years later with dense root systems and no root rot. That's not a scientific sample size, but it's consistent with what the plant pathology literature says about aeration and drainage in tropical foliage mixes.

What to skip

Several popular commercial aroid mixes are overpriced for what you get:

The one I get asked about most is Fox Farm Ocean Forest. It's excellent for heavy-feeding edibles. For aroids, the bat guano and fish meal nutrient load is more than the plants can use, and the peat base still compacts. I've tried it with pothos as a budget aroid substrate — the plants survived but didn't thrive the way they do in the chunky mix.

How to actually repot into aroid mix

Repotting into a new substrate is the moment where most substrate improvements succeed or fail. A few specifics:

1. Choose a pot only one size up (2 inches in diameter maximum). A pot that's too large holds more soil than the roots can dry out, which defeats the drainage benefits of the chunky mix.
2. Remove as much old soil as possible. Rinse the root ball under lukewarm water. If you're going from Miracle-Gro to aroid mix, removing the dense old soil prevents a moisture-retention pocket at the core of the new mix.
3. Let roots air out for 30 minutes before repotting. Gives you time to inspect for rot and allows any damaged roots to callous slightly.
4. Check for root rot — healthy aroid roots are white to tan and firm. Brown-black mushy roots need to be trimmed with sterile scissors before repotting. Let trimmed roots dry for an hour before the new substrate.
5. Water lightly after repotting, then wait a full week before the next watering. The plant is stressed and benefits from settling into the new substrate dry rather than wet.

For snake plant or other succulents, don't use this mix — they need even less organic matter and more grit. See the best soil for snake plant page for that recipe.

Frequently asked

Can I use this mix straight from the bag without the DIY step?

The closest single-bag option is Better-Gro Special Orchid Mix (ASIN B005OK9KRK). Used straight it's adequate but benefits from adding 20% more perlite and a handful of worm castings. If you absolutely don't want to mix ingredients, Better-Gro straight from the bag is better than any peat-based potting soil. The DIY recipe costs less per potting and gives you more control over the final texture — once you do it twice it takes about five minutes.

How often do I need to replace aroid mix?

A good chunky aroid mix holds its structure for two to three years before the organic components break down enough to compact. I refresh every 18–24 months at repotting. The signal to repot is when drainage slows — water sitting on the surface for more than 5–10 seconds before absorbing is a sign the mix is starting to compact. At that point, repotting into fresh substrate is more effective than trying to aerate the existing mix.

Does the mix work for all aroids, or just monstera and philodendron?

I use this ratio for monstera, philodendron, anthurium, pothos, and alocasia with consistent results. For orchids (which are epiphytic, not hemiepiphytic) I'd use pure orchid bark with no coir. For ZZ plant, which stores water in its rhizomes, I increase perlite to 30% and reduce coir to 30%. The principle — fast drainage, high aeration, low compaction risk — is the same across all aroids, just with different ratios based on how drought-tolerant the species is.

Sources

• University of Florida IFAS Extension — Tropical Foliage Plant Production: https://edis.ifas.ufl.edu/publication/EP001
• UConn Soil Testing Lab — Plant pH Preferences: https://soiltesting.cahnr.uconn.edu/plant-ph-preferences/
• NC State Extension Plant Toolbox — Monstera deliciosa: https://plants.ces.ncsu.edu/plants/monstera-deliciosa/
• Royal Horticultural Society — Houseplant potting media guidance: https://www.rhs.org.uk/plants/guides/house-plants
• Plantonix Coco Bliss (ASIN B01N1YP8O6): https://www.amazon.com/dp/B01N1YP8O6
• Better-Gro Special Orchid Mix (ASIN B005OK9KRK): https://www.amazon.com/dp/B005OK9KRK
• Espoma Organic Perlite (ASIN B002Y0AK6S): https://www.amazon.com/dp/B002Y0AK6S
• Wiggle Worm Worm Castings (ASIN B00V4RI88Y): https://www.amazon.com/dp/B00V4RI88Y