Gardenia

Gardenia: how do you recognise it?

Habit

Compact, densely branched shrub, 50–80 cm tall and wide in a pot.

Leaves

Elliptic, 5–10 cm long, leathery and glossy dark green, opposite or in whorls of three.

Flowers

Waxy white, 5–8 cm across, single or double, borne singly at the shoot tips. Turning creamy yellow after a few days.

Scent

Heavy, sweet and creamy, with a hint of jasmine: hence the name jasminoides.

Fruit

Rare indoors: an orange, elongated berry with lengthwise ribs.

Roots

Fine and sensitive to lime, waterlogging and drying out.

Flowering: May–August · Plants: March–April · Pruning: August–September

Why grow it?

• One of the most fragrant houseplants: a few flowers will scent a whole room.
• Glossy dark green leaves that look good all year, even when it is not in flower.
• A long flowering season, from May to August, with a steady supply of new flowers.
• It can spend the summer on a terrace or balcony in a sheltered, bright spot.
• A single flower floating in a bowl of water stays fragrant for a whole day.

Gardenia: where does it grow best?

• Plenty of light, but no harsh midday sun: by an east- or west-facing window, or a little back from a south-facing one.
• An even temperature of 18–22 °C by day and slightly cooler at night; never below 12 °C.
• Humid air: stand it on a tray of pebbles and water, and not above a radiator.
• No draughts and no sudden temperature changes. Do not move it once it has buds.
• Out of reach of cats, dogs and young children.

Light

Bright, out of direct sun

Potting soil

Multi-purpose compost or airy, humus-rich compost

Acidity

Acid

Watering

Moderately

Size

0.8 m tall, 0.8 m wide

Temperature

Minimum 12 °C

Goes well with

• Indoor azalea: Also likes acid compost, rainwater and a light, cool spot.
• Pink jasmine: Another fragrant houseplant, flowering in late winter and spring, before the gardenia.
• Wax plant: Also waxy, fragrant summer flowers, but much easier to care for.
• Boston fern: Fine, fresh fronds beside the glossy leaves; grouped together they keep the air more humid.

Gardenia: when and how to plant it?

Plant in March–April.

1. Repot in March–April, every 2–3 years or when the roots fill the pot, and never when it is in bud.
2. Choose a pot 2–3 cm wider than the old one, with a drainage hole.
3. Use acid compost, such as ericaceous compost for azaleas or rhododendrons, with a little perlite for good drainage if you like.
4. Set the plant at the same depth as before and firm the compost lightly.
5. Water with rainwater or softened water at room temperature until it runs out of the bottom, and empty the saucer after a quarter of an hour.

Care

Watering

Keep the compost evenly moist, never soggy and never bone dry. Use rainwater or softened water at room temperature.

Humidity

Stand the pot on a tray of pebbles and water. Mist the leaves with rainwater, but not the flowers: they get brown spots.

Feeding

From April to August, every 2 weeks, a feed for acid-loving plants, such as azalea feed, at half strength. None in winter.

Summer outdoors

From mid-June to early September it can stand outside in a sheltered, partly shaded spot, as long as nights stay above 15 °C.

Repotting

Every 2–3 years in March–April, always in acid compost.

Tip: Leave a watering can of rainwater indoors overnight: that gives you lime-free water at room temperature, exactly what a gardenia wants. Do not move it once it is in bud.

Gardenia: when to prune it?

Pruning months: August–September.

When: Straight after flowering, in August–September. Pruning is not essential, but it keeps the plant compact and bushy.

How:

• Cut over-long shoots back to just above a leaf or pair of leaves.
• Remove faded and browned flowers to keep the plant looking tidy.
• Cut dead and weak twigs out at the base.

Caution: Do not prune later than September: after that you remove next year’s flower buds.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Tip cuttings

From April to June, take 8–10 cm cuttings from non-flowering shoots. Remove the lower leaves and insert them in moist, acid cutting compost under plastic at 21–24 °C. Roots form in 4–8 weeks.

Gardenia: how does it get through the winter?

• Indoors all year: it cannot take frost and already suffers below 12 °C.
• In winter it prefers slightly cooler conditions, 15–18 °C, in the lightest spot in the house, away from draughts and hot radiators.
• Water less, but never let the root ball dry out completely. No feeding.
• Raise the humidity to counter the dry air from central heating.

Diseases and pests

• Bud drop: Buds turn yellow and fall before opening. Causes: moving the plant, draughts, dry air, a root ball that is too dry or too wet, or large temperature swings. Leave it in one place and keep conditions even.
• Yellow leaves with green veins: Chlorosis caused by lime in the water or compost. Use only rainwater and acid compost, and an iron-containing feed if needed.
• Red spider mite: Fine pale speckles and webbing on the leaves in dry air. Rinse the plant under the shower and raise the humidity.
• Mealybug and scale: White woolly tufts or brown scales on stems and leaf veins. Remove them with a cotton bud dipped in alcohol or a small soft brush.
• Aphids: On young shoots and buds. Rinse off with lukewarm water.

Through the year

• January: Keep cool and light. Moderate watering, no feeding.
• March: Repot if the roots fill the pot. Water a little more.
• April: Repot. Azalea feed every 2 weeks. Take tip cuttings.
• May: First flowers. Do not move it any more. Feed.
• June: Full flower. Feed. From mid-June it can go outside in a sheltered spot.
• July: Flowering. Water regularly with rainwater. Remove faded flowers.
• August: Last flowers. Last feed. Prune lightly after flowering.
• September: Prune lightly, by now at the latest. Bring indoors in early September.
• October: Water less. Light spot without draughts.
• November: Cool, light and even. Raise the humidity.
• December: Little water, no feeding. Away from the radiator.

Edible and useful

Not edible. Gardenia is mildly poisonous: cats and dogs that chew the leaves or fallen flowers may get vomiting and diarrhoea. It is of little danger to people, but do not let small children put flowers or leaves in their mouths. Keep the pot out of reach of pets and clear up fallen flowers and leaves. If any is swallowed, call a poison centre (in Belgium 070 245 245) or your doctor at once.

Did you know?

• The genus is named after Alexander Garden, an 18th-century Scottish physician and naturalist who lived in South Carolina and corresponded with Linnaeus.
• In China and Japan the orange fruits have been used for centuries to colour food and fabrics yellow.
• The name jasminoides means ‘jasmine-like’ and refers to the scent of the flowers.