Gardenia

The Gardenia is a tender evergreen or semi-evergreen flowering shrub that requires greenhouse treatment in the UK.

They can grow to a height of 1.2 metres (4ft) with a similar spread.

The scented flowers appear in late June to August.

Some may flower during the winter months if grown in a warm well lit spot.

During the winter months they require a minimum temperature of 12°C (55°F) and should be kept just slightly moist.If watering is required use water that is at room temperature.

From May till October, water the plants freely, preferably rainwater, and feed every week with a liquid fertiliser high in nitrogen.

Over winter, feed at six-week intervals with a balanced fertiliser.

Plants can be placed outdoors for the summer months (June-Sept)They can grow to a height of 1.2 metres (4ft) with a similar spread.

If kept in the greenhouse, keep the atmosphere humid by damping down the floor/ground beneath them.

Placing the pots on saucers filled with water and gravel or clay pellets will increase the humidity around the plants.

Keep the water level below the top of the gravel/pellets.They can grow to a height of 1.2 metres (4ft) with a similar spread.

Mist the leaves frequently in hot weather, but not when in flower.(water can damage the flowers)

Avoid direct sunlight, shade if necessary, and if the temperature rises to say 18°- 20°C (65°- 70°F) ventilate the greenhouse more.

Pests and Diseases:

Bud drop:

Is usually due to extreme or fluctuating temperatures.

Move plants to a location that is kept at a constant temperature.

Buds are also prone to drop when watering is irregular.

Similarly, if over or under watered, avoid both dry and or water-logged conditions.

Leaf problems:

Yellow growing points (chlorotic) and slow growth are caused by lack of light and low temperatures.

Yellowing of leaves can particularly affect the new growth.

This is most likely down to an iron deficiency but could be root damage caused by over watering.

If overwatering is not to blame, apply a top dressing of chelated (sequestered) iron.

Too much water leads to yellowing of leaves and leaves fall prematurely, too little water causes leaf browning at the tips and edges.

Wilting of leaves, even though compost is moist can indicate that moisture is being lost through the leaves more rapidly than it can be taken up by the roots.

Move plant to a shadier position and mist the leaves three times a day, with rainwater, until the plant has recovered.

Flowering problems:

Lack of flower formation can be due to hot nights of 18°C (65°F) or more, and /or a dry atmosphere.

Provide humidity by placing plants on a gravel/clay pellets tray and provide ventilation to reduce temperatures.

Stand plant on a gravel tray over spring and summer.

Pests:

Plants can be affected by Aphids, Mealybugs, Red spider mite and Scale insects.

Treat as appropriate.

Cultivation

Week 2: Sow seed in pots/trays of seed compost and germinate at 21°C (70°F)

Germination will take around 4-5 weeks.

Week 4: Pot up seedlings from previous year into 100-125mm (4"-5") pots of ericaceous potting compost and grow on in a frost free environment.

Ensure they get maximum light but not direct sunlight.

Week 10: Take heel cuttings from non flowering lateral shoots, and root at a temperature of 18°- 20°C (65°- 70°F)

Once rooted pot up the cuttings into individual 70mm (3”) pots and grow on at the same temperature.

Week 12: Prick out seedlings into 70mm (3") individual pots of ericaceous potting compost and grow on in a frost free environment.

Ensure they get maximum light but not direct sunlight.

Week 15: Re-pot established plants annually into ericaceous potting compost, until they are in 200mm (8”) pots.

Week 30: Pinch out the growing tip of the cuttings to promote bushier growth.

Week 35: Generally pruning only amounts to keeping the plant tidy and nicely shaped.

Prune back new growth of established plants by half or two thirds after flowering.





Top of the Page