🪴 Advice
🌱 Repotting
🌿 In brief
An all-purpose potting mix suits most indoor plants, provided it is lightened with perlite. Demanding families - cacti, orchids, carnivorous plants, aroids - need a specific mix, and this is often where the difference lies between a plant that stagnates and one that grows.
We choose our plant carefully, our pot with taste, and pour in the first bag of potting soil we find on the shelf. Yet the substrate is what constantly surrounds the roots: it determines how much air they receive, how quickly water drains, and what the plant can absorb. Here's how to choose the right mix, family by family, and how to rescue overly compact commercial potting soil.
Why potting soil matters
A root needs more than water and nutrients: it needs to breathe. A substrate therefore performs three functions at once, and it is their balance that makes a good mix.
Letting air through
Roots consume oxygen. In compacted, waterlogged potting soil, they suffocate and rot - this is the leading cause of indoor plant death.
Retaining just enough water
A good substrate stays moist for a few days, then dries out. If it remains wet for two weeks, it retains too much moisture for the plant or the pot.
Holding the plant in place
The mix must anchor the roots without compacting. Potting soil that settles over successive waterings eventually forms an impermeable block.
In other words, problems attributed to watering very often come from the substrate. If you feel you are watering correctly and the plant still declines, it is the mix you need to examine - before changing your watering schedule.
What's in potting soil
A bag of potting soil is not garden soil. It is a blend of a few materials, each with a specific role. Knowing them lets you read a label and make your own mix.
Water-retaining bases
Blond peat is the historical base of potting soil: light, acidic, and highly water-retentive. Its main drawback is environmental, and it becomes difficult to rewet when allowed to dry out completely. Coconut fiber serves the same purpose with a better environmental footprint and rehydrates easily: it is now the base to prioritize.
Materials that provide aeration
Perlite, those small white balls, creates air pockets without retaining water: it is the most useful and least expensive additive. Vermiculite does the opposite: it retains water and minerals. Composted pine bark, in pieces, provides lasting aeration and decomposes slowly - essential for aroids and orchids. Coarse sand, finally, adds weight and improves drainage: reserved for cacti.
What provides nutrients
Compost and vermicompost provide the nutrients. Commercial potting soils contain enough to last about six to eight weeks: after that period, fertilizer takes over, not the potting soil.
⚠️ Never use garden soil
It compacts in a pot, becomes water-repellent after a few waterings, and brings larvae, seeds, and fungi. Even when excellent in the garden, it is unsuitable for an indoor pot.
The right mix for each family
There is no need to buy six different bags. Basic potting soil, perlite, and bark are enough to cover almost every case, simply by varying the proportions.
| Family | Recommended mix |
|---|---|
| Common foliage plants Pothos, Ficus, Dracaena, Sansevieria |
All-purpose potting soil + 20% perlite. Simple, airy, and sufficient for the vast majority. |
| Aroids Monstera, Philodendron, Anthurium, Syngonium |
Equal parts potting soil, pine bark, and perlite. Thick roots that require plenty of air. |
| Cacti and succulents | Special cactus potting soil, or equal parts potting soil, coarse sand, and perlite. It must dry quickly. |
| Calathea, Maranta, ferns | Potting soil and coconut fiber, with a little perlite. Constant moisture without standing water. |
| Orchids | Bark only, never potting soil. The roots are aerial and rot in a standard substrate. |
| Carnivorous plants | Pure blonde peat, or peat and sand, with no fertilizer or compost. Rich potting soil kills them. |
| Seeds and cuttings | Very light, low-nutrient mix: coconut fiber and perlite. Roots develop better in a poor substrate. |
The only two cases where this is genuinely non-negotiable are orchids and carnivorous plants: standard potting soil is fatal to them in the short term. For everything else, adjusting the proportions is enough.
Improving store-bought potting soil
Most budget universal potting soils are too fine and retain too much water: they are suitable for flower beds, not for a houseplant pot. A few steps make them perfectly usable.
- Always add 20 to 30% perlite, whatever the plant: it is the most worthwhile step.
- For plants with large roots, mix in a handful of pine bark pieces.
- Break up compacted clumps by hand before filling the pot, without ever compacting it afterward.
- Lightly moisten the mix before repotting: dry potting soil repels water during the first watering.
- Choose potting soil made with coconut fiber rather than pure peat, as it is much easier to rehydrate.
A good test, once the pot is filled: pour in some water. It should pass through and come out of the holes within a few seconds. If it pools on the surface or takes a minute to drain, the mix is too compact - and no watering schedule will compensate. This is also the time to check that the pot is suitable for the plant's size.
Drainage: what really works
Drainage is the subject of a widespread belief: a layer of clay pebbles at the bottom of the pot is thought to improve water drainage. In reality, in a pot with drainage holes, this layer does not drain anything at all - it even creates a saturated zone just above it and reduces the volume of soil available to the roots.
What really provides drainage is a drainage hole and an aerated growing medium. Nothing else. If your pot has drainage holes and your mix is suitable, you do not need any layer at the bottom.
💡 When clay pebbles are genuinely useful
In an unperforated decorative pot: a thin layer of pebbles raises the nursery pot and keeps it from sitting in the water that drains out. There, they are useful - and that is their only real use.
Then there are decorative pots without drainage holes, which we love for their appearance. The safest solution is to keep the plant in its nursery pot with drainage holes and slide it into the decorative pot, taking it out to water it if necessary. Planting directly in a sealed container means watering blindly, without ever knowing what is accumulating at the bottom.
Finally, substrate wears out: it compacts, becomes depleted, and accumulates salts. After two years, even when well maintained, it needs to be renewed - that is the whole purpose of repotting, which remains the most effective way to revive a stagnant plant.
Verdeia - Pots and decorative pots
The right container for the right mix
Pots with drainage holes, ceramic decorative pots, baskets made from natural fibers: find the container that lets roots breathe without sacrificing style.
Frequently asked questions
For most green plants, yes, provided you add 20 to 30% perlite. Cacti, orchids, and carnivorous plants require a specific mix.
No: in a pot with drainage holes, they do not improve drainage. They are only useful at the bottom of an unperforated decorative pot to raise the nursery pot.
No: it compacts, becomes water-repellent after a few waterings, and brings unwanted larvae and seeds into the home.
It creates air pockets between the particles without retaining water, preventing the substrate from compacting and the roots from suffocating.
About every two years: after that, the substrate becomes compacted, depleted, and laden with salts, even with good care.
Well supported
Plants that get off to a good start
Our plants arrive in fresh substrate suited to their family: for the first few months, they need nothing more than a good spot.
