Repotting guide

When & how to repot Rex Spider Orchid (Brassia 'Rex')

Also called Rex Spider Orchid, Brassia Rex.

More about rex spider orchid

About Rex Spider Orchid

Brassia 'Rex' · also called Rex Spider Orchid, Brassia Rex · tropical

Brassia 'Rex' (B. verrucosa × B. gireoudiana) is one of the most popular spider orchid hybrids, combining vigorous growth with spectacular flower spikes. Large, greenish-yellow blooms with dark brown markings and extremely elongated sepals appear on arching spikes that can reach 60 cm. An adaptable, rewarding orchid for intermediate to warm conditions.

Mature size: 40–60 cm (16–24 in) tall; flower spikes 45–60 cm (18–24 in) bearing 5–12 flowers with sepals reaching 15–20 cm (6–8 in)

Watch for — Limp or yellowing leaves: Most often caused by humidity below 40% or chronic underwatering. Check that roots are not desiccated, raise humidity, and adjust watering frequency. Yellow leaves closest to the base may simply be natural ageing of the oldest pseudobulbs.

How to tell rex spider orchid needs repotting

Repotting on a calendar is less reliable than reading the plant. For rex spider orchid, 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 rex spider orchid 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 rex spider orchid

Every 1–2 years, when the bark breaks down. Rex Spider Orchid's growth habit — sympodial epiphyte forming robust clumps of oval pseudobulbs with broad, strap-shaped leaves and arching basal inflorescences — sets the pace. Brassia 'Rex' (B. verrucosa × B. gireoudiana) is one of the most popular spider orchid hybrids, combining vigorous growth with spectacular flower spikes. Large, greenish-yellow blooms with dark brown markings and extremely elongated sepals appear on arching spikes that can reach 60 cm. An adaptable, rewarding orchid for intermediate to warm conditions.

What size pot to step rex spider orchid up to

Keep rex spider orchid 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 rex spider orchid

Repot rex spider orchid 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 rex spider orchid

Repot after flowering. Wait until rex spider orchid 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 rex spider orchid into the same or one-size-up pot of fresh coarse medium-grade bark orchid 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 rex spider orchid 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 rex spider orchid

Rex Spider Orchid wants medium-grade bark orchid mix. Use a well-draining medium of medium-grade fir bark, perlite, and charcoal. The mix should dry sufficiently between waterings to prevent root anaerobia while retaining enough moisture to prevent desiccation. Repot every 2 years into fresh bark. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting rex spider orchid — frequently asked questions

How often should you repot rex spider orchid?

Every 1–2 years, when the bark breaks down for rex spider orchid. Repot rex spider orchid 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 medium-grade bark orchid mix. Old, decomposed bark suffocating the roots is the real problem.

What size pot does rex spider orchid need?

When is the best time of year to repot rex spider orchid?

Why does rex spider orchid 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 rex spider orchid. Refresh it into fresh coarse bark just after flowering.

Should you fertilise rex spider orchid after repotting?

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