Rex Spider Orchid (Brassia Rex) care

Light

In the wild rex spider orchid grows on the bright edge of a forest canopy, not in the canopy and not in the open. Indoors, that translates to within a metre of an unobstructed window, sheer curtain optional. Thrives in bright, filtered light — avoid direct sun, which causes leaf scorch. An east- or west-facing window, or a shaded south window, is ideal. Partial shade (around 40% shade cloth in a greenhouse) replicates the dappled conditions in which both parent species naturally grow. The fastest test: a hand held at the leaf casts a soft-edged shadow at noon — sharp shadow means too much sun, no shadow means too little light.

Watering

Aim for 2–3 times per week during active growth; weekly or less in cooler rest period for rex spider orchid, but treat that as a starting point rather than a rule. A south-facing summer windowsill will dry the pot twice as fast as a north-facing winter room. Lift the pot; if it feels noticeably lighter than it did wet, water it. Keep the medium slightly but consistently moist during growth; never waterlogged. Use rainwater or reverse-osmosis water at room temperature. A brief dry rest period after new pseudobulbs mature stimulates flowering — reduce watering until spikes emerge.

Soil and pot

Rex Spider Orchid grows best in 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. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Rex Spider Orchid sits happiest at around 40–60% humidity and 13–32°C (55–90°F). Brassia 'Rex' accepts slightly lower humidity than many of its species parents, making it more accommodating indoors. Below 40%, roots on the pot surface dry out and leaves can become limp. A humidity tray or room humidifier keeps conditions comfortable without excessive misting. If you keep the room above 13–32°C year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed rex spider orchid sparingly. Feed weakly and frequently — quarter-strength balanced fertiliser (20-20-20) at every watering during active growth. Switch to a high-phosphorus bloom booster as pseudobulbs harden and a rest is approaching. Do not fertilise during the dry rest period. Flush with plain water once a month. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on rex spider orchid in the Growli community. Each is annotated with the most common cause so you know where to start.

• 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.
• Failure to initiate flower spikes — Brassia 'Rex' needs a clearly defined but brief rest once new pseudobulbs are fully formed. Allow the medium to dry more than usual and reduce temperatures by 5–8°C (9–14°F) for 4–6 weeks. Resume normal watering once spikes appear.
• Scale insects — Brown or white waxy bumps on pseudobulbs and leaf undersides are scale. Remove manually with a cotton swab dipped in isopropyl alcohol and treat with horticultural oil or systemic insecticide for heavy infestations. Improve air circulation to deter recurrence.

Propagation

Divide at repotting, retaining at least three pseudobulbs per division. Because 'Rex' is a hybrid, divisions will be true to the parent plant whereas seed propagation would produce variable offspring. Back-bulbs with dormant eyes can be potted separately in moist sphagnum moss. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Rex Spider Orchid is pet-safe. Brassia 'Rex' is a hybrid within Orchidaceae. Orchids as a family have no known toxic principles, and the ASPCA lists numerous orchid genera as non-toxic to cats and dogs. Brassia is not individually cited by the ASPCA, but neither parent species (B. verrucosa, B. gireoudiana) has any documented toxic compound. Ingesting plant material may cause mild GI upset. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Rex Spider Orchid deep-dive guides

Every aspect of rex spider orchid care, each with its own calibrated guide:

• Rex Spider Orchid watering schedule
• Rex Spider Orchid light requirements
• Best soil mix for rex spider orchid
• Rex Spider Orchid fertilizing guide
• When to repot rex spider orchid
• How to propagate rex spider orchid
• Rex Spider Orchid growth rate & size
• Rex Spider Orchid cold hardiness
• Rex Spider Orchid temperature & humidity
• Is rex spider orchid toxic to cats & dogs?
• Is rex spider orchid toxic to cats?
• Is rex spider orchid toxic to dogs?

Featured in these plant shortlists

Rex Spider Orchid qualifies for 6 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

• Best pet-safe houseplants — Houseplants the ASPCA lists as non-toxic to cats and dogs — every one verified against the ASPCA toxic and non-toxic plant list.
• Best plants for a north-facing window — Houseplants for a north-facing window: bright, even, indirect light and no scorching direct sun. Each pick verified against its documented light needs.
• Best pet-safe plants for bright light — Non-toxic to cats and dogs and happy in a bright, sunny spot — safe plants for your best-lit windowsill.
• Best fast-growing houseplants — Houseplants documented as fast or vigorous growers — quick to fill a pot, cover a pole or trail down a shelf.
• Best cat-safe plants — Houseplants the ASPCA lists as non-toxic to cats (and dogs) — safe greenery for a home with a curious cat.
• Best dog-safe plants — Houseplants the ASPCA lists as non-toxic to dogs (and cats) — safe greenery for a home with a curious dog.
• Browse all 29 plant shortlists — pet-safe, low-light, drought-tolerant and more

Related guides

Rex Spider Orchid is also commonly called Rex Spider Orchid or Brassia Rex.

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• All 6887 plant care guides in the Growli library