In many parts we are anxiously waiting for the first gardenia flowers to appear. Gardenias will grow well out of their preferred tropical or warm climate native habitat, even tolerating a little frost, but they can be slow to bloom in cooler areas. Best flowering occurs when days are warm and nights are still reasonably cool. Usually by Christmas time gardenias are in full bloom.
To flower well, most gardenias need some sun. They’ll grow in full sun in cooler areas but, in most climates, their favourite aspect is morning sun and afternoon shade. Water the plant regularly but make sure the water can drain away. Dry gardenias will drop their buds and, possibly, even some of their leaves. Mulch over the root system with an organic layer (milled cow manure is ideal) and make sure that potted gardenias, particularly, aren’t allowed to dry out between waterings.
When potting up gardenias, dig some pre-soaked Yates Waterwise Water Storing crystals into the potting mix – they’ll help hold extra moisture. In very dry climates it can also be helpful to mist spray water over the leaves on hot days, although not when the sun is directly hitting the plant.
There are many gardenia cultivars but the perennial favourite is Gardenia augusta ‘Florida’, a medium grower with mid-sized blooms. Gardenia radicans is a hardy little ground cover and the new ‘O So Fine’ has smaller leaves and a softer overall appearance. There are some taller growing gardenias such as Gardenia magnifica or G. Professor Pucci. And if you have lots of room and want something really different, grow the tall (to 3-4m, South African gardenia called Gardenia thunbergia.
Feed gardenia plants a couple of times a year with a slow acting, general fertiliser such as Yates Dynamic Lifter Soil Improver & Plant Fertiliser. Another option is to feed every two weeks through spring, summer and autumn with Yates Thrive Roses & Flower Liquid Plant Food. Gardenias prefer an acidic soil so, if necessary, treat with Yates Soil Acidifier Liquid Sulfur to lower pH.
Sometimes in spring the old leaves of gardenias turn yellow. This is usually caused by the magnesium in the older leaves moving into the new ones. Mostly the problem rights itself as the weather gets warmer, but a spring treat like Yates Leaf Greener Magnesium Chelate can hasten the improvement.
Watch for scale and sooty mould on the leaves. Spray with PestOil or Scale Gun and wait for a number of weeks until, after the scales have died, the mould gradually falls away. Gardenias will take quite hard pruning, which can be done in late winter/early spring in most areas. Autumn pruning works well in warm climates.