How to grow gardenia

Depending on the variety, grow gardenia either as an indoor plant or in the garden. Originating from China, and named after the botanist Alexander Garden, Gardenia jasminoides has been grown as a greenhouse or conservatory plant for over 200 years and latterly as a house plant. More recently, with the development and breeding of hardier varieties, gardenia can now be grown as an outdoor plant in sheltered sites or mild areas. Indoor gardenias can be tricky to grow as they are exacting in their requirements. Outdoor varieties of gardenia are more straightforward to grow although still need care in their siting and maintenance.

Gardenias start to decline after about five years old and are best replaced with new plants.

How to grow gardenia

Depending on the variety, grow gardenia indoors or outside in lime-free soil or potting compost, in good light but out of direct sunlight. Plants grow to between 60cm-1.5m high according to variety and pot size. Use rainwater to keep the compost evenly moist, and feed regularly. Prune in spring and propagate by cuttings taken in spring or summer. Indoors, they require an even temperature and a high level of humidity to thrive.

Gardenia: jump links

• Planting gardenia
• Caring for gardenia
• Propagating gardenia
• Growing gardenia: problem-solving
• Buying gardenia
• Best gardenia to grow

Where to grow gardenia

Outdoors

Outside, gardenia is best grown in a pot so it can be moved under cover in winter to protect from frosts or winds. In areas with favourable conditions year-round, plant gardenia in a raised bed or in the ground. Grow hardy gardenias in light shade: the dappled shade cast by larger plants is ideal, or in a spot that gets good light without direct sunlight. Shelter from wind is essential. In mild areas, hardy gardenias can remain outdoors all year. Otherwise, move into a porch, greenhouse, or conservatory for the winter.

Indoors

Even temperatures, bright light out of direct sun during summer, a humid atmosphere and a draught-free spot, are all key to success with gardenias in the home. To achieve a high level of humidity, place the plant on a large tray or saucer filled with pebbles or clay granules, and keep filled with water to just below the top level of the pebbles.

Temperatures in summer should ideally be no lower than 15°C at night and no higher than 24°C by day. During winter, move the plant to a well-lit spot – direct sun is fine at this time of year – and with an optimum minimum temperature of 15°C.

How to plant gardenia

A lime-free soil or compost is essential for gardenias. Use an ericaceous (lime-free) potting compost for house plants or pot-grown outdoor gardenias. If planting in borders or raised beds, check the soil pH (the level of acidity or alkalinity) and if necessary to improve soil, use a lime-free soil conditioner. Plant gardenias outside in spring or summer. Use a good-sized pot (minimum 30cm wide and deep) if growing in a container.

Caring for gardenia

Water using rainwater or filtered water and keep the compost moist, so it's neither too wet nor too dry. Correct watering is particularly important during winter when it is easy to overwater. Water should always be tepid, not cold.

Feed every 1-2 weeks during spring and summer with a diluted liquid feed that's high in nitrogen. During autumn and winter, feed once a month with a balanced liquid fertiliser.

In spring, prune lightly to maintain an even bushy shape and shorten leggy shoots.

How to propagate gardenia

Gardenias are relatively straightforward to grow from cuttings, either taken from young shoots in spring (softwood cuttings), or in mid to late summer from the current season’s growth that has just started to become woody (semi-ripe or half-ripe cuttings).

Growing gardenia: problem solving

Yellowing leaves are a sign of distress that can result from a number of causes including too little light, too much water, low temperatures, or water that contains too much lime.

• Too little light is easily remedied by moving the plant into a brightly lit spot, although take care not to go to the other extreme as gardenias dislike direct sunlight
• Check the pot is not sitting in water and ensure the plant is sited where excess water drains freely – on a saucer of pebbles is idea
• Water using collected rainwater or filtered water. Be aware that an indication of ‘hard’ or limy mains water is a build-up of scale in your kettle and dishwasher
• Yellowing of the shoot tips usually indicates that temperatures are lower than the plant requires

Bud drop can occur if the plant becomes stressed due to growing conditions being less than ideal.

Lack of flowers may be due to insufficient or incorrect feeding, a dry atmosphere, or high temperatures.

Pests may appear on gardenias and are most likely on plants growing under cover. These include red spider mite, aphids, and mealybugs. As with all pest problems, be vigilant, inspect plants regularly for signs of trouble, and take action as appropriate as soon as possible before the problem intensifies.

Varieties of gardenia to grow

• Gardenia jasminoides – an attractive house plant with a gorgeous scent. H x S: 60cm x 60cm
• Gardenia 'Crown Jewels' – white, waxy, scented double blooms. Suitable for growing in a pot on the patio or in a sheltered border. Hardy but may need protection in severe winters. Height x Spread: 60cm x 120cm
• Gardenia jasminoides 'Kleim's Hardy' – single white blooms with a strong fragrance. Grow in a pot or sheltered border. Hardy. H x S: 90cm x 90cm
• Gardenia 'Celestial Star' – another hardy variety with double blooms that have scrolled petals at the centre. H x S: 1.2m x 1.2m