Houseplant Potting Mix Chooser
Updated · Sproutly
Pick the plant group and the problem you can see. The result is a starting mix built on University of Maryland Extension’s potting groups and checked against the species guides on this site. The bark-and-perlite loosening for aroids and the LECA and pon notes are this site’s guidance, not UMD’s. It does not assign a watering interval.
Four mixes, plus minerals
| Group | Starting point | What changes the choice |
|---|---|---|
| Aroid or chunky foliage | Soilless mix, loosened with bark and perlite | A dense bag labeled potting soil stays too wet. |
| Succulent or cactus | Less humus, and a purchased mix high in sand | A moisture-holding peat mix is the wrong correction for a pot that dries quickly. |
| Orchid or bromeliad | Bark that drains. One published mix is 1 part peat, 6 parts fir bark, 1 part charcoal | UMD puts anthuriums in this group. NC State describes moist, well-drained soil for Anthurium andraeanum. |
| Ferns, peace lily, African violet | Soilless mix that holds moisture and still drains | A cactus mix would dry a fern out. A wet saucer is still too wet. |
| LECA or pon | An inorganic medium that needs fertilizer | It is not a substitute for the soil mix the plant group would have used. |
University of Maryland divides houseplant media into foliage, flowering, cactus, and orchid groups, and says most commercial mixes contain no garden soil. The perlite, sphagnum, LECA, and pon entries explain the ingredients.
A wet pot is not a reason to water
After repotting, University of Maryland says to water thoroughly and then wait until the top of the mix dries. A heavy pot waits, even when the plant is a fern. Gravel in the bottom of the pot does not create drainage. The same page says to cover the hole with a shard, not to fill the base with gravel.
Unglazed clay dries faster than plastic or a glazed pot. That is useful for a succulent and a problem for a fern that is already drying out in a day. The pot size calculator is the next check when the container is the issue. A much larger pot stays wet around a small root ball.
When a species guide disagrees
The moth orchid guide uses bark and replaces it when the bark breaks down or sphagnum will not rewet, following NC State’s Phalaenopsis profile. Anthurium andraeanum is where the sources differ. University of Maryland groups anthuriums with orchids and bromeliads as epiphytes that can rot in regular potting mix. NC State describes moist, well-drained soil for the houseplant. A chunky, airy mix that stays lightly moist satisfies both. Use the anthurium guide for that species.
University of Maryland suggests about one teaspoon of superphosphate per quart in general foliage and flowering mixes. Superphosphate can contain fluoride, so leave it out for fluoride-sensitive plants such as a dracaena or a spider plant. The teaspoon is not part of the succulent or orchid result.
Frequently Asked Questions
Use a soilless mix matched to the plant. Penn State says garden soil can bring disease and pest problems indoors. University of Maryland says bags labeled potting soil are usually too dense for roots.
University of Maryland describes one part peat, six parts fir bark, and one part medium charcoal as a common orchid mix. A non-bark alternative they mention is charcoal, perlite, and a premium potting mix. Replace bark when it breaks down into something that holds water.
LECA is expanded clay. Pon is a mineral blend. Both need a fertilizer plan. A chunky aroid mix is still a soilless mix with bark and perlite.
University of Maryland describes the properties of a foliage mix and does not publish a Monstera recipe. A percentage invented here would look more precise than the source.
Sources & further reading
- University of Maryland Extension: potting and repotting indoor plants
- Penn State Extension: repotting houseplants
- NC State Extension: Phalaenopsis
This guide combines the references above with practical decision steps for home growers. Conditions and cultivars vary. How we approach plant guidance · Suggest a correction