Orchids

Vocabulary

Orchid forums and vendor labels lean heavily on a handful of terms — knowing them is the difference between guessing and reading.

Pseudobulb

A swollen above-ground stem that stores water and nutrients between flushes. Cattleyas, Dendrobiums, and Oncidiums grow them; Phalaenopsis don't.

Sympodial vs monopodial

Sympodial orchids creep sideways — each new pseudobulb is a new shoot off the rhizome (Cattleya, Dendrobium). Monopodial orchids grow up from a single crown, adding leaves at the top (Phalaenopsis, Vanda).

Velamen

The spongy white outer layer on aerial roots. Soaks water like a paper towel; turns green when wet because chlorophyll shows through. Damaged velamen does NOT recover — handle dry roots gently.

Spike

The flower stalk emerging from a node. On Phalaenopsis, the spike comes from between leaves; on Dendrobium it comes off the cane; on Cattleya it emerges from a sheath at the top of the pseudobulb.

Keiki

Hawaiian for "baby" — a clonal plantlet that forms on a node, especially common on Dendrobium and Phalaenopsis spikes. Can be removed and potted once it has 2–3 roots.

Sheath

The leaf-like covering at the apex of some pseudobulbs (Cattleya) where the spike develops. A green sheath isn't a guarantee of bloom; brown sheaths often still hide a viable spike.

Backbulb

An old, leafless pseudobulb still attached to the rhizome. Often divided off as a propagation unit — given moisture, many will produce a new growth.

Crown rot

The number-one Phalaenopsis killer. Water settling in the central crown of a monopodial orchid rots the growing tip. Water from the side or wick from below; never overhead-water a Phal.

Growth habits

Orchids look bewildering until you split them along three axes: where they grow, how they grow, and when they rest.

Care basics

Cross-cutting rules that apply to almost every common orchid. Genus-specific quirks layer on top.

Light

Brighter than most houseplants. Phalaenopsis tolerates a north window; Cattleya and Vanda want strong indirect or filtered direct sun. Yellow-green leaves = good. Dark forest-green leaves = too dim.

Watering

Soak when the medium is just shy of dry — bark feels dry to the touch, sphagnum looks pale. Most root deaths are from chronic wetness, not under-watering. Smaller pots dry faster than larger ones.

Humidity

50–70% suits most species. Tropical Vandas and many Dendrobiums prefer 70%+. A pebble tray under the pot does almost nothing; a humidifier does. So does grouping plants.

Fertilizer

"Weakly, weekly" — quarter-strength balanced orchid fertilizer at every watering during active growth, less in winter. Flush with plain water once a month to prevent salt buildup.

Repotting

Every 1–2 years for bark; every 2–3 years for sphagnum, before the medium breaks down. Best done right after flowering or when new roots are emerging. Cut dead roots; trim the medium back to firm tissue.

Key genera

Where most growers start, and what makes each one a different proposition.