Cymbidiums are terrestrial plants whose pseudo-bulbs are sheathed and surmounted by long leaves. The large flower spikes bear two to 25; there are no hard and fast rules as to their culture. If the greenhouse is kept at a temperature and atmosphere that the gardener himself finds comfortable, the plants will thrive.
Water them fairly frequently, except during cold, damp weather and ventilate the greenhouse whenever possible. Even night air can be admitted when the outside temperature is unusually high in summer, but never expose cymbidiums to draughts.
Keep the temperature between 45 and 80° F. (7 and 27° C), and use artificial heating as little as possible. In winter never attempt to force the temperature much above 50° F. (10° C); on many days it will naturally and beneficially rise higher, and at night the temperature will drop to 45° F. (7° C).
If there is a heavy frost or a breakdown in heating, and the temperature drops below 45° F., keep the plants dry, place them on the ground, and cover them with layers of paper. They will then survive many degrees of frost for a short time, and will flower well, although later in the season—in May.
Shading is necessary in early spring and summer, and should be in place by the end of February or early March.
Give less shade in autumn in order to harden the plants for the winter and to ensure (lowering.
Winter is the flowering season for cymbidiums in the British Isles, the early-flowering kinds starting as early as November. All continue flowering until May.
Cut the flowers when the top bloom has been open a full week and they will last several more weeks in water.
Repot the plants after flowering when the new growths are 3 to 6 in. high. Cut away all dead roots and, if there are too many healthy roots, shorten them to 4 in. Do not be afraid of cutting them, because the thick, heavy pseudo-bulbs will keep the plants going for some time. Repot into reasonably large pots, but add one part fibrous loam to the compost.
After repotting do not water the compost for seven to ten days, but if possible keep the foliage syringed and the tops of the pots slightly dampened to encourage new root action.
Further details about the culture of orchids can be obtained from articles that appear in gardening periodicals. The prospective orchid grower is also advised to visit a reputable orchid nursery before making a choice of plants.