Category: Orchid Care

Pronounced: VAN-dah

The pride of tropical orchid growers, Vandas are a challenge to grow in Canada because of their need for warmth, high light and humidity. Successful culture of these plants is possible, and brings forth stunning flowers in white, yellow, green, yellow orange red and burgundy shades as well as blue. Fast growing and frequent bloomers, Vandas can be
most rewarding.

Healthy Vandas start with healthy roots:

• Pot in a very coarse medium. Fir bark mixtures are best, with 2.5 to 3.5 cm chunks of bark. In humid areas, plants may be grown without any medium, hanging from a wire, however, if they are potted, some large chunks of bark or charcoal may be required to hold the plant in place.
• Repot when plant outgrows its pot. Because no pot is really required, this is mostly for the grower’s convenience in handling the plant.
• Typically the existing pot will be covered with roots inside and out and should simply be placed into a larger pot without disturbing the roots any more than necessary. Roots growing around the pot will bend more easily if moistened first. Choose a clay pot or cedar basket.
• Vandas will grow roots over the side of the pot and up into the air as well as out from the stem well above the pot. Leave these roots on the plant, perhaps misting them when the plant is watered.
• Roots should be soaked at least once daily, more often in sunny, warm weather, and then allowed to dry before the next soaking. Water thoroughly, particularly if your water has a high mineral content.
• Do not use water softened in salt-consuming water softeners. Low mineral water is preferred, such as naturally soft water or rain water. If hard water is used, water very heavily to flush minerals. Use room temperature or warmer water.
• Fertilize frequently with a balanced fertilizer. One-quarter to one-half strength recommended by manufacturer for house plants every week in spring and summer and every two weeks in autumn and winter.

Healthy leaves produce more and bigger flowers:

• High to very high light levels are appropriate for most. Terete Vandas (with cylindrical leaves) require the most light while Ascocenda and Rhynchostylis need less light. Leaves should be a medium green, not yellowish or dark green. They should be firm, not long and floppy (more light needed). A slight red blush indicates good light on some plants while a red blush which covers the leaves indicates too much light.
• Three or more hours of sun on a west, south or east window, or under a bank of 8 fluorescent light tubs, or HID sodium or metal halide lights. Only the shorter varieties are appropriate under fluorescent lights. In areas of dark, overcast winters, artificial lighting may be a must.
• Vandas do best with 70-80% humidity, but will grow and bloom, although more slowly and with fewer flowers, in lower humidity. Use humidifier to raise humidity – humidity pans and misting rarely effective. Enclosing plant growing areas is effective but ensure fresh air and air movement to avoid mold and rot.
• Grow Vandas in warm temperatures with 18°C minimum winter nights and 35°C summer day maximum. Ensure 6-12°C day/night difference to aid flower formation. Vanda coerulea and hybrids, as well as Neofinetia hybrids require slightly cooler temperatures to initiate flowering. Vandas usually bloom every few months and the flowers last for two to three weeks:
• Maintain plant orientation while spike is growing for best display.
• Buds turning yellow, wilting and falling prior to opening is from not enough energy in the plant to open the flower either because the light is too dim, the plant is too small, or the roots have rotted. Also caused by ethylene gas (given off by ripening fruit) or by drastic temperature changes

Pronounced: den-DROH-bee-um

So called because of the resemblance between their flowers and those of the Phalaenopsis or moth orchid, the vigorous and easy to grow plants produce large numbers of flowers through the year, in colors of white, pink, purple and combinations. The upright plants trace their ancestors to South East Asia and Australia. The genus Dendrobium contains hundreds of different species of which the plants discussed here are only a small part. Other Dendrobiums may have radically different cultural requirements.

Healthy Dendrobiums start with healthy roots:

• Pot in a coarse medium. Fir bark mixtures are best, with 1.5 to 2.5 cm chunks of bark, perlite and charcoal.
• Repot when the growth has reached the edge of the pot or if the medium is beginning to decompose (usually after about two to three years). Repot as new growths are just starting to form.
• Remove old medium if it is loose and any rotting roots; choose a plastic pot just big enough to hold the roots, and position the plant so that the new growths will have room to grow without reaching the edge of the pot.
• These plants like a rapid drying cycle – grow in the smallest possible pot. The plants may become top heavy and require the plastic pot be slipped into a clay pot to lower the center of gravity.
• Roots should be moist at all times when the plant is in active growth but should dry out somewhat as the growth matures and when the plant is not actively growing.
• When watering, water thoroughly, with a volume of water at least equal to that of the pot.
• Do not use water softened in salt-consuming water softeners. Low mineral water is preferred, such as naturally soft water or rain water. If hard water is used, water very heavily to flush minerals.
• Fertilize weakly and frequently with a balanced fertilizer. One-eighth to one-quarter strength recommended by manufacturer for house plants every week in spring and summer and every two weeks in autumn and winter

Healthy leaves produce more and bigger flowers:

• Medium to high light levels are appropriate. Leaves should be a light green, not yellowish (too much light) or dark green (too little light). They should be somewhat stiff, not long and floppy (more light needed). A reddish edge to the leaves indicates the light is on the upper boundary of a proper level of light.
• Two to four hours of sunshine on an East, West or South window sill, or under HID sodium or metal halide lamps. A bank of 4 to 8 fluorescent tubes may also be successful for miniature varieties. With full sized plants reaching 1 – 1.5 m, fluorescent light is not likely to be effective for the larger plants.
• Sticky, honey-like sap may form on stems and leaves. This is a natural occurrence in high light, but may also signal an insect infestation. Examine your plant carefully for pests should this occur.
• Dendrobiums do best with 60-70% humidity but will grow and bloom at somewhat lower humidity levels. Use humidifier to raise humidity – humidity pans and misting minimally effective. Enclosing plant growing areas is ffective
• but ensure fresh air and air movement to avoid mold and rot.
• Dendrobium phalaenopsis hybrids are warm growing, with night minimum temperatures of 18°C and day maximums of 32°C.

Dendrobium phalaenopsis may bloom at any time during the year and the flowers last for four to eight weeks:

• Maintain plant orientation while spike is growing for best display.
• Buds turning yellow, wilting and falling prior to opening is from not enough energy in the plant to open the flower either because the light is too dim, the plant is too small, the roots have rotted. Also caused by ethylene gas (from ripening fruit) or drastic temperature changes.

Crosses between various species and genera in the Oncidiinae tribe, have resulted in plants that have come a long way from the original species in beauty and ease of culture. These plants start blooming small with spikes of fancifully patterned flowers in shades of white, yellow, red and brown, and as they mature become large, robust plants with long stems of flowers.

Healthy Oncidiums start with healthy roots:

• Pot in a fine medium. Fir bark mixtures are best, with 0.5 to 1.0 cm chunks of bark, perlite and charcoal.
• Report when the medium starts to break down or when the new
  growth will be over the edge of the pot.
• Remove old medium if it is loose, any rotting roots or brown bulbs; choose a plastic pot that will allow for 2 to 3 new growths and position in the pot so that the new growths will grow from the middle to the edge.
• Roots should dry out somewhat between watering. When the plant is actively growing, water when medium has just begun to dry out but is still slightly damp. When the plant is completing its growth start to let it dry more, to encourage flowers rather than vegetative growth. When it is dormant, typically in winter, do not water until medium is almost completely dry. When watering, water thoroughly, with a volume of water at least equal to that of the pot.
• Do not use water softened in salt-consuming water softeners. Low mineral water is preferred, such as naturally soft water or rain water. If hard water is used, water very heavily to flush minerals.
• Fertilize weakly and frequently with a balanced fertilizer. One-eighth to one-quarter strength recommended by manufacturer for house plants every week in spring and summer and every two weeks in autumn and winter.

Healthy leaves produce more and bigger flowers:

• High light levels are appropriate. Leaves should be a light green, not yellowish (too much light) or dark green (too little light). They should be firm, not long and floppy (more light needed). A slight red blush indicates an ideal light level on some plants. A more pronounced red blush will indicate too much light.
• Four hours of sunshine on a windowsill (West or South) or 6-12” under an eight tube fluorescent fixture or under an HID sodium or metal halide lamp. Plant size usually prevents mature plants growing under fluorescent lights.
• Recent pseudobulbs should be firm; if wrinkled, check roots for rot, and report if necessary. High humidity (such as enclosing the plant in a plastic bag) will aid recovery if most or all of roots lost, but be careful of rot.
• Oncidiums do best with 50-60% humidity but when mature will grow and bloom, although more slowly, in lower humidity. Use humidifier to raise humidity – humidity pans and misting minimally effective. Enclosing plant growing areas is effective but ensure fresh air and air movement to avoid mold and rot.
• Grow Oncidium hybrids in intermediate temperatures with 14°C minimum winter nights and 29°C summer day maximum. Ensure 6-12°C day/night difference to aid flower formation.
• Some varieties prefer slightly different temperatures:
  • Warmer temperatures: Brassia hybrids, including Miltassia, Beallara and Maclellanara.
  • Cooler temperatures: Odontoglossum hybrids, including Vuylstekeara and Odontioda.

Oncidiums usually bloom annually and the flowers individually last for three or more weeks:

• Maintain plant orientation while spike is growing for best display.
• Oncidiums often provide much superior flower size and color as mature plants than as first bloom seedlings.
• Buds turning yellow, wilting and falling prior to opening is from not enough energy in the plant to open the flower either because the light is too dim, the plant is too small, or the roots have rotted. Also due to ethylene gas (given off by ripening fruit), or large temperature changes.