Light should be as bright as possible (3,500-4500 fc.), short of direct midday sun which can sunburn the leaves, especially if light is increased suddenly. Hawkes (1965) reported that "Full sun-exposure is required in most cases for proper production of flowers." Because of heavy cloud cover during the summer rainly season, "full sun" might not be as bright as one might expect.

Strong air movement should be provided at all times.

Arachnis Species

• Arachnis annamensis
• Arachnis batizocoi
• Arachnis batizogaea
• Arachnis beccarii
  • Arachnis beccarii var. imthurnii
• Arachnis breviscapa
• Arachnis calcarata
  • Arachnis calcarata ssp. longisepala
• Arachnis canniformis
• Arachnis cathcarthii
• Arachnis celebica
• Arachnis clarkei
• Arachnis evrardii
• Arachnis grandisepala
• Arachnis hookeriana
• Arachnis imthurnii
• Arachnis limax
• Arachnis longicaulis
• Arachnis longisepala
• Arachnis lyonii
• Arachnis maingayi
• Arachnis muelleri
• Arachnis philippinensis
• Arachnis siamensis
• Arachnis vanmullemii

Temperatures: Throughout the year, days average 82-90 F and nights average 72-74F, with a diurnal range of 8-17F. In their habitat the warmest days occur in later spring, but the warmest nights and smallest diurnal range occur in winter. The diurnal range is greatest in spring and summer, the result of warmer days rather than cooler nights.

Humidity. 80-85% year round.

Water: Rainfall in the habitat is heavy all year. Cultivated plants should be watered heavily while actively growing but the roots must be well aerated, and conditions around the roots should never become stale or soggy.

Rest: Growing conditions should be maintained all year. Water and fertilizer should be reduced somewhat in winter, especially for plants grown in the darker, short day conditions common in temperate latitude winters. Plants should be allowed to dry slightly between waterings, but they should never dry out completely or remain without water for long periods. Fertilizer should be reduced when water is reduced.

Growing Media: According to Hawkes: where the climate allows, Arachnis species with their long vinelike stems grow "best in specially prepared, raised beds, in a perfectly drained compost made as rich as possible, this to include shredded osmunda (or tree-fern fibre), sphagnum moss, gritty white sand, and manure or other fertilizing materials, addition of loam, leaf-mould, and perhaps even portions of bark preparations may also be made in moderation, with good effect." If grown in containers, large, perfectly drained pots should be used to accommodate the rampant root systems. Because of the plant's heavy water requirement, the medium should be open, well-aerated, and fast-draining but still retain some moisture. Conditions around the roots should never be stale or soggy, and the medium should be replaced before it breaks down too far.