Recently I have had many people asking me so many questions about Gardenias and my Gardenias suffer from the same problems as everyone else’s at this time of the year. Yellowing of the leaves is a common problem at the height of the flowering season. I have them planted under my bedroom window and the perfume at night is magical. These shrubs give a romantic feel to the garden or pergola area and are worth growing for evergreen looks and fragrance. Gardenias need a specific food and they really love a good slow release fertiliser like Yates Camellia Azalea food. When they are trying to flower and they are a bit hungary and they will sacrifice the old leaves by turning yellow and dropping. Simple to fix; just feed them. Generally a slow release fertiliser will release with temperatures above 25 degrees being the optimum and if it gets too hot they can release so quickly that the tiny balls of fertiliser burst and can burn surface roots and foliage low to the ground. Something to be aware of and you can avoid this by feeding in early spring and autumn for the best results and prevent the hungry look in the first place. Gardenias are renowned for throwing flowers spasmodically throughout the year so it’s a good idea just to get into the regular routine of twice a year feeds.
Interesting enough Gardenias have some friends who like the same treatments and fertiliser. Use your Camellia Azalea food to feed Gardenias, Camellias, Azaleas, Rhododendrons and Daphne plants and you will keep them very happy and healthy.
There are quite a few different species and varieties out there to choose from and you can purchase them as standards, bush or groundcovers. My favourites are Gardenia augusta ‘Magnifica’ which has a large flower and gives a great floral show with beautiful perfume. I also really like the variety G. ‘Professor Pucci ‘and the groundcover Gardenia, G. radicans. The ground cover has small cute flowers the same pure white as all the other Gardenias and are still highly scented.
Gardenias like a good loamy composted soil in a semi shaded aspect and they don’t like the frost too much or drying out so don’t forget to water these babies. They also prefer a slightly acid soil with a PH of 6-7. Easy to test your soil before planting with a simple do it yourself PH soil testing kit you can purchase form a Hardware store or Nursery. IF you need to raise your PH level because it is too acidic just add some lime or if you need to lower it if it is too alkaline add some sulphur. Most plants respond well to a PH of 6-7 and this is the zone where all the nutrients are available to plants we should only play with it when we are trying to manipulate the soil PH for specific plant requirements or where our soil is extreme either side of the scale and nutrients therefore become unavailable.
The most common pest problem I have seen on these plants is scale, small half shelled insects that suck goodness from the leaves and stems. A simple application of pest oil will get rid of these tiny critters and stops other issues like black sooty mould which grows off the sugar secretions of the scale.
I prefer pest oil to white oil it’s more environmentally friendly and not so harsh on the plant in hot weather. Good luck and get planting!