Repotting guide

When & how to repot Spider Orchid (Brassia) (Brassia spp.)

Also called Spider orchid, Brassia orchid, Spider Brassia.

More about spider orchid (brassia)

About Spider Orchid (Brassia)

Brassia spp. · also called Spider orchid, Brassia orchid · flowering

Brassia, the spider orchid, is an epiphytic genus in the Oncidiinae prized for star-shaped blooms with dramatically long, spider-leg tepals on arching spikes. Grow it in bright indirect light, intermediate temperatures and orchid bark, watering when the medium nearly dries. Generally regarded as non-toxic, but Brassia is not individually ASPCA-listed, so verify with your vet.

Mature size: Compact orchid, typically reaching about 45-60 cm (18-24 in) tall including the arching flower spikes; pseudobulb clumps spread slowly to a similar width over several years.

Watch for — Root rot from overwatering or stale mix: Soggy or decomposed bark suffocates roots, turning them brown and mushy. Use an open mix, let the medium nearly dry between waterings, and repot in fresh bark every 2-3 years.

How to tell spider orchid (brassia) needs repotting

Repotting on a calendar is less reliable than reading the plant. For spider orchid (brassia), watch for these signs:

The bark medium has broken down into a dark, soggy, soil-like mush that no longer drains.
Roots are climbing out of the pot in all directions (this is normal for spider orchid (brassia) and not on its own a reason to repot).
Roots inside the pot are brown, soft and rotting rather than firm and green/silver.
It is about two years since the last repot, or you can smell sour, decomposing bark — repot just after flowering finishes.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot spider orchid (brassia)

Every 1–2 years, when the bark breaks down. Spider Orchid (Brassia)'s growth habit — sympodial, epiphytic orchid: it spreads horizontally from a rhizome, producing a row of plump, flattened pseudobulbs each topped with one to three strap-shaped leaves. arching flower spikes emerge from the base of mature pseudobulbs, carrying up to a dozen or more star-shaped, long-tepaled "spider" blooms, often spotted yellow, cream, green or brown and sometimes fragrant. — sets the pace. Brassia, the spider orchid, is an epiphytic genus in the Oncidiinae prized for star-shaped blooms with dramatically long, spider-leg tepals on arching spikes. Grow it in bright indirect light, intermediate temperatures and orchid bark, watering when the medium nearly dries. Generally regarded as non-toxic, but Brassia is not individually ASPCA-listed, so verify with your vet.

What size pot to step spider orchid (brassia) up to

Keep spider orchid (brassia) in the same size pot, or go up just one, only if the roots have genuinely outgrown it. Orchids flower better slightly snug, and a big pot of bark stays wet and rots the roots. The reason you are repotting is the broken-down bark, not a need for more space — a clear pot lets you watch the roots.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot spider orchid (brassia)

Repot spider orchid (brassia) immediately after the flowers have finished, just as new roots or a new growth start to emerge — those fresh roots establish quickly in new bark. Never repot an orchid in full bloom; you will drop the flowers and shock the plant.

Step-by-step: repotting spider orchid (brassia)

Repot after flowering. Wait until spider orchid (brassia) has finished blooming and is pushing new roots. Soak the pot first so the roots are pliable and less likely to snap.
Remove all the old bark. Slide the plant out and crumble away every scrap of broken-down bark — that soggy mush is the actual problem you are fixing.
Trim dead roots. Cut off any brown, hollow or mushy roots with sterilised snips. Keep all the firm green/silver ones.
Repot into fresh bark. Settle spider orchid (brassia) into the same or one-size-up pot of fresh coarse free-draining medium-grade orchid bark mix, working bark between the roots so there are no big air gaps.
Hold off watering briefly. Mist or wait a few days before the first proper water so any cut roots seal. Then resume the normal soak-and-drain rhythm.

Aftercare

Give spider orchid (brassia) a few days before its first proper watering so cut roots seal, then return to the weekly soak-and-drain. Keep it bright, humid and out of direct sun while new roots grip the fresh bark. It may pause growth briefly; that is expected. Do not fertilise for about 3 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for spider orchid (brassia)

Spider Orchid (Brassia) wants free-draining medium-grade orchid bark mix. Use a coarse, open epiphyte mix based on medium-grade fir bark, optionally with perlite, charcoal or coconut husk for aeration; never standard potting soil. Pot in a container with generous drainage. Repot every 2-3 years in spring with fresh bark as the mix breaks down, but never repot while in bloom. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting spider orchid (brassia) — frequently asked questions

How often should you repot spider orchid (brassia)?

Every 1–2 years, when the bark breaks down for spider orchid (brassia). Repot spider orchid (brassia) every 1–2 years — but because the bark medium has broken down and gone soggy, not because it has outgrown the pot. Do it just after flowering, into the same size or one up, using fresh free-draining medium-grade orchid bark mix. Old, decomposed bark suffocating the roots is the real problem.

What size pot does spider orchid (brassia) need?

When is the best time of year to repot spider orchid (brassia)?

Why does spider orchid (brassia) get repotted if it isn't outgrowing the pot?

Because the bark medium breaks down. Over 1–2 years the chunky bark rots into a dense, soggy, soil-like mush that suffocates the roots — that, not size, is why you repot spider orchid (brassia). Refresh it into fresh coarse bark just after flowering.

Should you fertilise spider orchid (brassia) after repotting?

Not immediately. Wait about 3 weeks after repotting spider orchid (brassia). Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.