Repotting guide

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

Also called King Spider Orchid.

More about brassia 'rex'

About Brassia 'Rex'

Brassia Rex · also called King Spider Orchid · flowering

Brassia Rex is a vigorous, large-flowered hybrid spider orchid (B. verrucosa x B. gireoudiana) bred for big, star-shaped, yellow-green flowers heavily barred with chocolate brown, often carried many to a spike. Easy and forgiving for a Brassia, it wants bright indirect light, an airy bark mix, warmth, and high humidity, and is one of the best spider orchids for beginners.

Mature size: Foliage 40-50 cm tall; arching spikes to 50 cm bearing flowers up to about 20 cm across including the long tapering petals. Forms a sizeable specimen clump over a few years.

Watch for — Root rot from a tired mix: Old, broken-down bark stays wet and suffocates roots. Repot into fresh coarse medium every 2 years and water only on a dry-down cycle.

How to tell brassia 'rex' needs repotting

Repotting on a calendar is less reliable than reading the plant. For brassia 'rex', watch for these signs:

Roots spiralling thickly out of the drainage holes or pushing the whole plant up out of the pot.
The pot is so packed that water runs straight through in seconds and barely wets the soil.
It has split a plastic pot, or the rootball is a solid mass with almost no soil left when you slide it out.
Growth and (for brassia 'rex') flowering have clearly stalled despite good light and feeding — but remember this plant likes being snug, so a little crowding alone is not a reason to repot.

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 brassia 'rex'

Only every 2–4 years, when genuinely crowded. Brassia 'Rex' is one of the plants that genuinely prefers a snug pot — it grows and flowers better with its roots a little restricted, so resist the urge to repot it on schedule. Sympodial epiphytic hybrid forming clusters of plump, flattened pseudobulbs each topped with strap leaves. Strong arching spikes rise from the base of mature bulbs, each carrying numerous large spidery flowers in a tidy row..

What size pot to step brassia 'rex' up to

Go up only one pot size — roughly 2–3 cm (about an inch) wider in diameter, no more. Brassia 'Rex' positively prefers a snug pot: it flowers and grows better when the roots are a little restricted. The single biggest repotting mistake here is over-potting — dropping brassia 'rex' into a pot two or three sizes up. All that surplus soil holds water the small root system cannot use, stays cold and wet, and rots the roots within weeks. When in doubt, choose the smaller pot.

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 brassia 'rex'

Early spring, just as new growth restarts, is the ideal window for brassia 'rex'. The plant is moving into its strongest growth phase and re-roots into fresh soil quickly. Avoid repotting in winter dormancy or, for flowering plants, while it is in bud or bloom — recovery is slowest then and you risk dropping the flowers.

Step-by-step: repotting brassia 'rex'

Confirm it actually needs it. Slide brassia 'rex' out and check the roots. Only continue if it is genuinely packed — this plant prefers a snug pot, so if there is still soil and room, put it straight back.
Pick a pot only one size up. Choose a pot just 2–3 cm wider with good drainage. Resist anything bigger; over-potting is the main killer here.
Ease it out gently. Water lightly the day before, then tip brassia 'rex' out, supporting the base. Tease the outer roots free only enough to stop them circling.
Repot at the same depth. Add a layer of fresh open epiphytic bark mix, set the plant so the soil line sits exactly where it did before, and backfill around the sides, firming lightly.
Settle it in. Water once to settle the soil, then let it sit. Hold off on more water until the top of the soil dries — fresh soil around a small root system stays wet for a while.

Aftercare

Because the new soil holds more water than the old crammed rootball did, ease right back on watering — let the top of the soil dry before you water brassia 'rex' again, or you will rot the roots in the very pot you just moved it to. Keep it out of harsh direct sun for a fortnight. Do not fertilise for about 4 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for brassia 'rex'

Brassia 'Rex' wants open epiphytic bark mix. Medium-grade fir bark with perlite and charcoal in a freely draining pot, or grow in a basket. The mix must stay airy; refresh it every couple of years just after blooming, as decomposed bark holds water and rots the thick roots. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting brassia 'rex' — frequently asked questions

How often should you repot brassia 'rex'?

Only every 2–4 years, when genuinely crowded for brassia 'rex'. Only repot brassia 'rex' every 2–4 years, and only when it is genuinely root-bound — it flowers and grows best slightly crowded. Step up just one pot size in spring using open epiphytic bark mix. The key mistake is over-potting: a too-big pot stays wet and rots the roots.

What size pot does brassia 'rex' need?

When is the best time of year to repot brassia 'rex'?

Does brassia 'rex' like to be root-bound?

Yes — brassia 'rex' genuinely flowers and grows best when slightly pot-bound, so do not rush to repot it. The mistake to avoid is over-potting into a much larger pot: the excess soil stays wet, the roots cannot use it, and the plant rots. Only repot every few years and only one snug size up.

Should you fertilise brassia 'rex' after repotting?

Not immediately. Wait about 4 weeks after repotting brassia 'rex'. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.