Why orchid pots have holes in the sides

An orchid pot full of slots looks like a manufacturing fault to anybody used to houseplants. It is the most important feature of the pot, and it follows directly from what an orchid root is.

Epiphytes do not live in soil

Most of the orchids sold as houseplants — phalaenopsis, dendrobium, oncidium and their relatives — are epiphytes. In the wild they grow on the bark of trees, not in the ground.

Their roots are anchors and moisture collectors, wrapped in a spongy white layer called velamen that absorbs water quickly and then dries. In their natural position those roots are exposed to moving air on all sides, and they are wet for a short time after rain and dry the rest of the day.

Put those roots in a sealed pot of compost and they stay wet. Wet plus no air is root rot, and root rot is what kills the overwhelming majority of orchids sold as gifts.

What the slots do

Three things.

Air to the roots. Velamen needs oxygen. Side slots let air reach the root mass through the whole depth of the pot, not just at the surface.

Fast drainage. Water leaves from the sides as well as the base, so the medium does not stay saturated at the bottom — which is exactly where the oldest, most vulnerable roots are.

Evaporation. The medium dries evenly instead of drying at the top and staying sodden below.

A pot with a single hole in the base does none of this properly. That is the difference between an orchid pot and a plant pot.

Why clear plastic

Not decoration, and not only so you can see the roots — although that is genuinely useful.

You can see the roots. Healthy roots are firm, green when wet and silvery-white when dry. Rotted roots are brown, soft and hollow. In an opaque pot you find out when the plant collapses; in a clear pot you can see it coming weeks earlier.

You can see the moisture. Condensation on the inside wall means the medium is still damp. No condensation and silvery roots means it is time to water. This is a far more reliable guide than a finger in the top of the bark.

Phalaenopsis roots photosynthesise. They contain chlorophyll and do contribute, modestly, when they get light. It is a small benefit and it is real.

The decorative pot problem

Orchids are sold as gifts, and a gift orchid frequently arrives inside a sealed ceramic or glass cachepot with no drainage at all.

Water goes in, water cannot leave, and it collects in the bottom. The lowest roots sit in it and rot. The plant looks fine for a month and then declines all at once.

The fix takes ten seconds: keep the orchid in its slotted plastic pot and use the decorative pot as an outer sleeve. Lift the inner pot out to water, let it drain completely in the sink, and put it back. Never let water stand in the outer pot.

Ceramic orchid pots designed for the job have drainage holes and usually a saucer, and are a different product from a cachepot.

Sizing

Orchids like being tight in their pots. A pot too large holds a volume of medium the roots do not occupy, and that unoccupied medium stays wet.

Standard sizes run 3, 4, 5, 6 and 7 inches across the rim, and the step from one to the next is the right amount of increase. When repotting, go up one size only if roots genuinely fill the current pot.

Assortment packs exist because a collection needs several sizes, and because a plant that has just been divided goes down a size rather than up.

Medium

Bark, sphagnum, perlite, charcoal or a mix — the common factor is that they are chunky and hold air. Ordinary potting compost in an orchid pot defeats the pot: the fine particles block the slots and hold water.

Bark drains fast and needs more frequent watering. Sphagnum holds much more water and is easier to overwater. In a humid climate like south Florida, bark in a slotted pot is the more forgiving combination.

Self-watering pots

These exist for orchids and work on a reservoir with a wick. They are useful for people who travel, and they demand more attention to the reservoir, not less — a reservoir left full for weeks is the sealed-pot problem in another shape.

Let the reservoir empty completely and stay empty for a day or two before refilling. Orchids want a wet-then-dry cycle, not constant moisture.

Where to look

Clear slotted pots, singly and in size assortments, are on the clear slotted orchid pots page — every listing gives the rim diameter. Ceramic pots with real drainage and self-watering designs are at ceramic and self-watering pots. Nursery pots for growing on are under nursery pots and tools, and if a spike needs holding up, that is plant stakes and supports and orchid clips.