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Plant care

Long Spider Orchid (Arching Brassia) care

Brassia longissima

Also called Long Spider Orchid, Arching Brassia.

RHS H1aUSDA 11-12Pet-safeIndoor 30–45 cm (12–18 in) tall

Watering rhythm

3-4days

Every 3–4 days in active growth; every 2–3 weeks in winter

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Light

Bright indirect light (just back from a sunny window)

Soil

Coarse bark-based orchid mix

Humidity

50–70%

Temp

13–30°C

Pet safety

Pet-safe

Mature size

30–45 cm (12–18 in) tall

Care at a glance

Light

Bright but filtered. Long Spider Orchid burns within days in unfiltered south-facing summer sun, and stops growing within months in deep shade. Needs bright, filtered light of 2,000–3,000 foot-candles — an east- or shaded south-facing window is ideal. A slight yellowing of leaves and reddish blush on pseudobulbs signals correct intensity. Avoid harsh direct midday sun, which causes bleaching and sunburn. If you only have a south window, set the plant back 1.5 m or hang a sheer curtain — both knock the intensity down into the right range.

Watering

Watering long spider orchid: every 3–4 days in active growth; every 2–3 weeks in winter. The number that matters isn't the day of the week — it's how dry the top 2-3 cm of the pot feels. A finger in the soil tells you more than a watering app. After every watering, tip the saucer. Water thoroughly with rainwater or reverse-osmosis water, allowing the bark medium to approach but not fully dry out between waterings. Reduce frequency significantly as temperatures drop and light levels decrease in winter. Never let the plant sit in standing water — root rot follows quickly.

Soil and pot

Long Spider Orchid grows best in coarse bark-based orchid mix. Use a fast-draining medium of medium-grade fir bark, perlite, and charcoal in roughly 3:1:1 ratio. Good air circulation around roots is essential. Repot every two years as bark breaks down and becomes water-retentive. 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

Long Spider Orchid sits happiest at around 50–70% humidity and 13–30°C (55–86°F). High humidity is critical; pseudobulbs shrivel when air is too dry. Stand the pot on a moist gravel tray (pot base above the water line) or use a room humidifier. Pair humidity with good airflow to prevent fungal rots. If you keep the room above 13–30°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 long spider orchid sparingly. Apply a balanced orchid fertiliser (e.g. 20-20-20) at quarter-strength every watering during active growth (spring–autumn). Switch to a low-nitrogen, high-phosphorus formulation as flower spikes initiate. Flush the medium with plain water monthly to prevent salt build-up. 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 long spider orchid in the Growli community. Each is annotated with the most common cause so you know where to start.

  • Shrivelled pseudobulbs — Caused by insufficient humidity or underwatering. Move the plant to a more humid spot, add a pebble tray, and check watering frequency. Once pseudobulbs are firm again, the plant recovers fully.
  • Root rot — Overwatering or a waterlogged medium causes roots to blacken and collapse. Remove affected roots, repot into fresh bark, and reduce watering intervals. Ensure the pot has generous drainage holes.
  • Failure to rebloom — Brassia longissima needs a brief, cooler and drier rest period once new pseudobulbs mature. Reduce watering and lower night temperatures to around 13–15°C (55–59°F) for 4–6 weeks to initiate flower spikes.

Propagation

Divide the rhizome at repotting time, ensuring each division has a minimum of three mature pseudobulbs plus at least one new growth (lead). Back-bulbs without a new growth seldom regenerate reliably. Allow cut surfaces to dry for several hours before potting into fresh bark. 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

Long Spider Orchid is pet-safe. Brassia is in the family Orchidaceae. The ASPCA lists numerous orchid genera as non-toxic to cats and dogs. Brassia is not individually named in the ASPCA database, but the genus has no known toxic principles and is consistent with the non-toxic orchid pattern. Ingestion of plant material may still cause mild gastrointestinal 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.

Long Spider Orchid care — frequently asked questions

What is the common name for Brassia longissima?

Brassia longissima is most commonly called Long Spider Orchid, but it is also known as Long Spider Orchid, Arching Brassia. The names refer to the same species, so care instructions for Long Spider Orchid apply identically to anything sold as Arching Brassia.

How much light does long spider orchid need?

Long Spider Orchid grows best in bright indirect light (just back from a sunny window). Needs bright, filtered light of 2,000–3,000 foot-candles — an east- or shaded south-facing window is ideal. A slight yellowing of leaves and reddish blush on pseudobulbs signals correct intensity. Avoid harsh direct midday sun, which causes bleaching and sunburn.

How often should I water long spider orchid?

Water long spider orchid every 3–4 days in active growth; every 2–3 weeks in winter. Water thoroughly with rainwater or reverse-osmosis water, allowing the bark medium to approach but not fully dry out between waterings. Reduce frequency significantly as temperatures drop and light levels decrease in winter. Never let the plant sit in standing water — root rot follows quickly. The finger-test (or lifting the pot to feel its weight) beats a fixed weekly calendar because pot size, light, and season all change how fast the soil dries.

Is long spider orchid toxic to cats and dogs?

Long Spider Orchid is pet-safe. Brassia is in the family Orchidaceae. The ASPCA lists numerous orchid genera as non-toxic to cats and dogs. Brassia is not individually named in the ASPCA database, but the genus has no known toxic principles and is consistent with the non-toxic orchid pattern. Ingestion of plant material may still cause mild gastrointestinal upset.

What USDA hardiness zone does long spider orchid grow in?

Long Spider Orchid is rated for USDA zone 11-12 and RHS hardiness H1a. Outside that range, grow it as a container plant that overwinters indoors before the first hard frost.

Long Spider Orchid deep-dive guides

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

Featured in these plant shortlists

Long Spider Orchid qualifies for 8 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

Related guides

Long Spider Orchid is also commonly called Long Spider Orchid or Arching Brassia.