Gardenia – Gardenia jasminoides

Of the 250 varieties of Gardenia, only one is grown in cultivation — Gardenia jasminoides, from China. Others are found in many tropical and subtropical areas of the world.

This plant was named after the 18th-century American botanist Dr Alexander Garden. The Latin name jasminoides refers to the very heady perfume, similar to that of the Jasmine flower.

Flowers and flowering Gardenia jasminoides flowers during the summer, from May until September, with the flowers appearing one after another. G. jasminoides ‘Florida’ is a double-flowering form, while G. Jasminoides ‘Fortuniana’ produces single flowers with a very strong fragrance. There is also a winter-flowering form, G. jasminoides ‘Veitchiana’.

The winter-flowering Gardenia should be watered generously in winter and kept at temperatures of 16-18°C (61°-65°F).Gardenia - Gardenia jasminoides

All cultivated Gardenias produce waxy, creamy-white flowers that tend to yellow as they mature. Care should be taken when handling the flowers, as they bruise easily.

Gardenias will eventually reach a height and spread of 60-90cm (2-4ft).

Propagation

The Gardenia can be propagated from tip cuttings in March and April.

Take cuttings about 13cm (5in) in length. If you do not have a seed tray with a rigid plastic lid, grow the cuttings in a pot covered with polythene to keep the humidity high. Bend a stiff piece of wire into a bow and place it over the cuttings, securing the ends in the compost; then pull the polythene bag over it.

The bag should be fastened around the rim of the pot. Make small holes in the polythene bag to prevent the plants rotting from too much condensation. Replace the polythene bag if it becomes opaque and make sure the damp bag does not touch the leaves.

Use a rooting compost made from equal parts sand and peat. Give some bottom heat and keep at a temperature of 24°C (75°F). When the cuttings have rooted — in 4 to 6 weeks time — move them to a cooler position with a temperature of 18°C (65°F). Repot when they are growing well.

Plant Problems

The leaves become sticky and the plant begins to weaken when aphids are present.

Treatment: Spray the plant with an insecticide. Repeat as necessary.

Fine webs appear on the leaves when the red spider mite infests the plants.

Prevention: Mist spray your plant frequently to keep the humidity high, as these pests will only attack in dry conditions. Combat a severe infestation by spraying with an insecticide.

Yellow or falling leaves may be caused by hard water or chlorosis, a trace element deficiency. Treatment: Use rainwater or boiled water cooled to room temperature. If this does not help, apply a sachet of chelated iron to the compost, following the instructions.

PLANT CARE

This needs extra care, and does best in a greenhouse or conservatory. Trim back leggy growth in March or April.

  • Potting: Repot every 2 years in early spring. Use a compost suitable for Erica varieties, or make one using equal parts peat, sand and humus or leaf mould.
  • Water moderately in summer and winter, keeping the compost evenly moist at all times. Use rainwater or boiled water cooled to room temperature. The water must never be cold.
  • Feeding: Feed once every 2 weeks when the plant is in flower with a standard liquid fertilizer diluted to half its normal strength.

CONDITIO NS

Light: Place in a position of partial shade. Never allow the plant to stand in direct sun.

Temperature: Keep at a minimum of 13°C (55°F) in winter. In summer, keep at 15-18°C (60— 65°F). If the temperature rises above 18°C (65°F) increase the humidity. Summer temperatures should not rise above 24°C (75°F).

When to buy

Available in spring from garden centres and nurseries.

Choose a plant that is about 20-25cm (8— 10in) high, bushy and with lots of buds. The leaves should be glossy green. Avoid any plants with yellow or falling leaves.

Given the proper conditions, your Gardenia will live for many years.

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