Odontoglossum

The Odontoglossum family includes about 100 species but to this figure can be added several thousand hybrids that have been bred by amateur and professional gardeners throughout the world.

In the wild, the Odontoglossum orchids grow as epiphytes in trees or on rocks. They come from the cool highlands of tropical America and some species thrive as high as 3000m (10,000ft) up in the mountains where night-time temperatures can drop to around freezing point in winter. To get house plants to bloom successfully, the temperatures and climate of the natural habitat have to be imitated as closely as possible.

Colours and varieties

The flowers of Odontoglossum orchids are usually reddish-brown with white or yellow patches, although some hybrids have various unusual colour combinations.

Odontoglossum grande is often referred to as the Tiger Orchid because of its striped pattern. The flowers bloom some time between autumn and spring and can be up to 15cm (6in) across.Odontoglossum

O. cordatum has heart-shaped flowers that are reddish-brown with touches of yellow and white. It blooms in the autumn.

Odontoglossum plants vary in height depending on the species or hybrid. Some are only 20cm (8in) tall while others grow to over 90cm (3ft).

Looking after your plant

The Odontoglossum orchids don’t need high temperatures and should be grown in unheated conditions. Water and feed your plants regularly during the growing period.

Rest periods

In order to guarantee flowering, these orchids need a rest period, usually during the winter months. They should be kept cool and should be provided with high humidity and good air circulation. Watering should be kept to a minimum as growth practically stops. Mist the leaves occasionally to keep up the humidity and avoid cold draughts.

You can propagate your plants quite easily by division when you repot them.

Pests And Diseases

A white powdery deposit that usually occurs on the leaves is mildew. It is quite commonly found on Odontoglossum orchids during the resting periods when the temperatures are low.

Treatment: Increase the ventilation around the plant but try to avoid creating draughts. Remove badly mildewed leaves and spray with a systemic fungicide.

Root rot is caused by overwatering during rest periods.

Treatment: Reduce watering immediately. In severe cases, take the plant out of its pot, remove the affected roots, repot in fresh compost and treat with a fungicide.

PLANT CARE

Like most orchids, Odontoglossum likes plenty of light and high humidity— mist the leaves regularly in summer.

  • Potting: Use a special orchid compost that contains osmunda fibre, coarse sphagnum and possibly granulated charcoal. These orchids like being potbound, so only repot every two or three years.
  • Water moderately during _ the growing period from late spring to early autumn. Reduce watering during the winter rest period.
  • Feeding: Use an orchid fertilizer during the growing season in summer. Do not feed during winter.

BEST GROWTH ENVIRONMENT

  • Light: These orchids prefer bright light but keep them out of direct sunlight. Orchids need about 10-15 hours of light daily to bloom.
  • Temperature: In the winter and early spring, keep the temperature of the room down to about 7°-13°C (45°-55°F). In summer and autumn, 13°-18°C (55°-65°F) is suitable.

Buying Tips

  • Different varieties are available at different times of the year, so there are no hard and fast rules. Specialist nurseries and large garden centres are the best places to look.
  • Choose plants with thick fleshy leaves with a healthy sheen. The bases of the stems (called pseudobulbs) should be swollen and firm.
  • Given proper conditions, these plants can give lasting pleasure for many years.

In an unheated conservatory the Odontoglossum orchids will produce their magnificent blooms. These orchids grow as epiphytes in the wild and need a cool winter rest.

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