Aroid Soil MixThe Exact Recipe for Monstera and Philodendron

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A four-ingredient mix of coco coir, orchid bark, perlite, and worm castings gives philodendron, monstera, and anthurium the fast drainage and root-zone air they need. The recipe is simple, the ingredients are all on Amazon, and it usually costs less per pot than bagged "aroid mixes." The recipe and product picks are based on the cited horticultural sources and manufacturer descriptions; they have not been tested hands-on.

What aroids actually need from soil

Many popular aroids — monstera, many philodendrons, and pothos — are climbers in nature. They start life on the forest floor and then climb trees, eventually rooting into crevices of bark, trapped organic debris, and the air itself via aerial roots. (Alocasias are the exception: they are upright, tuberous plants that grow in soil.) Their roots are adapted to airy conditions that wet and dry irregularly.

That biology matters for what you put them in:

1. Drainage above everything else. Water should run through the pot quickly, not pool.
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.
4. Slightly acidic pH. UConn's soil pH table lists philodendron, monstera, dieffenbachia, and aglaonema at pH 5.0–6.0.

Standard Miracle-Gro Indoor Potting Mix is peat-based and can end up failing all four criteria. 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

This mix is aimed at aroids such as heartleaf philodendron, monstera deliciosa, anthurium, and golden pothos. The ratio follows the Cornell epiphytic mix that Clemson HGIC lists for Monstera and Philodendron: equal parts fir bark, sphagnum peat and perlite. Clemson describes coir as a lower-cost, more sustainable alternative to peat, so this version uses coir in place of peat. Worm castings are an optional addition here; the Clemson recipe gets its nutrients from added lime and fertilizer instead.

Ingredients

1. Plantonix Coco Bliss Coco Coir — the base

This Plantonix listing is a 5-pack of 650g compressed bricks. One brick hydrates to roughly 8–10 quarts of loose coir. For a batch of aroid mix you'll use part of a brick. The bricks store indefinitely sealed, so one pack covers several batches.

One important preparation step: rinse the hydrated coir before using. Clemson HGIC advises rinsing coir thoroughly with water before use to avoid soil salinity issues. 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 for aroids, but it benefits from adding a bit more perlite and some 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 fertilize regularly with a liquid fertilizer, straight Better-Gro is an excellent time-saver.

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. Perlite can be dusty, so open the bag outside or wear a dust mask when measuring; 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, so it covers many potting sessions. Store it sealed to prevent it from drying out or attracting fungus gnats.

The mix ratio

Equal parts by volume, following the Cornell epiphytic mix in Clemson HGIC's soil mix guide, with coir standing in for peat:

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

How these picks were chosen

The recipe and the products in it were picked from manufacturer specifications and from what the cited sources say aroid roots need, chiefly the RHS houseplant growing guide and the NC State Extension Plant Toolbox. The mix and the products have not been tested hands-on. The equal-parts ratio comes from the Cornell epiphytic mix in Clemson HGIC's soil mix guide.

What to skip

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

Fox Farm Ocean Forest also comes up often. 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.

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 (Clemson HGIC advises 1 or 2 inches larger in diameter). 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 briefly 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 before adding the new substrate.
5. Water lightly after repotting, then let the mix dry 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 extra perlite and some 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.

How often do I need to replace aroid mix?

Eventually the organic components break down: Iowa State Extension notes that potting soil becomes more compacted and poorly drained over time, which is a sign it's time to repot. The signal is when drainage slows — water sitting on the surface instead of soaking in. 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?

Clemson lists the source mix for Monstera, Philodendron, Dieffenbachia and Hoya; this guide uses the same ratio for monstera, philodendron, anthurium, pothos, and alocasia. For orchids (which are epiphytic, not hemiepiphytic), use pure orchid bark with no coir. For ZZ plant, which stores water in its rhizomes, use more perlite and less coir. 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

• UConn Soil Testing Lab — Plant pH Preferences: https://soiltesting.cahnr.uconn.edu/plant-ph-preferences/
• Clemson HGIC — Indoor Plants: Soil Mixes: https://hgic.clemson.edu/factsheet/indoor-plants-soil-mixes/
• Clemson HGIC — Indoor Plants: Transplanting and Repotting: https://hgic.clemson.edu/factsheet/indoor-plants-transplanting-repotting/
• Iowa State University Extension — How to Care for Houseplants: https://yardandgarden.extension.iastate.edu/how-to/how-care-houseplants
• NC State Extension Plant Toolbox — Monstera deliciosa: https://plants.ces.ncsu.edu/plants/monstera-deliciosa/
• Royal Horticultural Society — How to grow houseplants: https://www.rhs.org.uk/plants/types/houseplants/growing-guide
• Plantonix coco coir, 5-pack (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