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Gardenias can be tricky to keep happy in pots. Here are five top tips for success

We’ve all been seduced by a well-grown gardenia at the garden centre, and figured it would make the perfect potted addition to our home. Who doesn’t have a spot that wouldn’t benefit from a potted gardenia, such as at the front door to welcome guests, on the back patio where its perfume can be enjoyed on lazy summer days, or in troughs as an informal hedge?

However, the reality for many is that it doesn’t take long for the gardenia to yellow, drop leaves and curl up its toes. Gardenias in pots can be difficult, but if you follow my no-nonsense tips, you’ll have glossy green foliage and fragrant flowers all summer.

1. Size really does matter

A potted gardenia needs room to develop a decent-sized root ball. In a small pot, the roots are restricted, and heat up quickly when sunlight hits the side of the pot. This makes for a stressed plant that dries out easily and produces little new growth and few flowers. So always plant gardenias into a big pot. Don’t bother with anything less than the size of a 9L bucket.

While we’re on the topic of pots, avoid black plastic and terracotta, as they dry out fast. If you really want terracotta, use a pot sealer to reduce water loss through the sides. And don’t skimp on potting mix – always choose premium quality.

The other size issue relates to the type of gardenia you grow. An ideal choice for a container plant is Gardenia augusta ‘Florida’, as it has compact growth up to about 1m high and a little wider (to 1.5m). Yes, there are other lovely gardenias that grow taller, but they are challenging to grow well in a pot.

2. Position, position

Gardenias need sunlight to thrive, but a potted specimen placed in scorching-hot sun really struggles, especially in regions with low humidity. A spot with morning sunlight and protection from the fierce afternoon rays is best. If you have to put a potted gardenia somewhere that bakes all day long, be prepared to water it daily, or even more frequently, throughout the hottest months of the year.

In cold climates, gardenias also need protection from cold winds, so in these areas they must be moved in winter to somewhere that is sheltered but still receives plenty of sunshine.

3. Thirsty plants

These gorgeous plant babies must be watered. While gardenias that are grown in the ground are a bit thirstier than other plants, put a gardenia in a pot and its need for regular watering ramps up.

To keep lush green leaves on a potted gardenia, water frequently to ensure the potting mix doesn’t dry out. In summer, this may mean every day. Yes, every day. Or connect the pot to an irrigation system for an easy fix. Without regular watering your potted gardenia will look terrible and its flower buds will drop unopened. Make sure there are drainage holes in the base of the pot so excess water can drain away.

4. Food, glorious food

I’m not going to mince my words here. Gardenias are greedy pigs. If you feed them regularly, they’ll reward you with dense green foliage and lots of beautiful flowers, but keep them on a diet and you’ll end up with sparse plants with pale, yellowing leaves and few flowers.

Fertilise potted gardenias every two months with a layer of aged cow manure and organic fertiliser pellets, and they’ll give you flowers in return. It you want to spoil them, a fortnightly dose of a liquid organic fertiliser is the icing on the cake.

And don’t get caught up worrying that yellow gardenia leaves means a specific nutrient is missing. If you feed your gardenia regularly, individual nutrient deficiencies won’t be an issue. By the way, it’s normal for older leaves (those lower down on the stems) to turn yellow and drop off. Leaves don’t last forever.

5. Pesky pests

It’s an unfortunate fact that pests love gardenias as much as we do. Top culprits include various types of scale, mealy bugs, mites and aphids. Ignore these sap suckers at your peril. Well, okay, at the peril of your prized gardenia. But seriously, if you don’t act, these pests will turn your plant into a sad specimen covered in sooty mould. Look for a flurry of ants on your plant as a sign of an infestation by a sap-sucking pest. Spray with a botanical oil or neem product for organic control.

Pests indicate that you’ve slipped up on one of the first four tips, so check that your plant is in a roomy pot in its ideal position, and that it’s being well watered and is not wanting for plant food.