GROWING A GARDENIA
Gardenias will persist in a wide range of conditions but, if they're not perfectly content, they will tend to look quite awful.
The Gardenia's fragrant flowers are contrasted by the thick, shiny dark green leaves. They can be pruned on a tall trunk into a topiary, kept as a bonsai, pruned as a normal shrub or grown as a tub specimen.
Gardenias come in many varieties to choose from.
They came initially from a warm climate so they don't like being freezing cold and they do not like it too hot. Gardenias need a protected position in the garden with some morning sun.
An east-facing location is ideal, where the plant can be shelter from the very hot afternoon sun. Gardenia plants will grow quite successfully in a large pot filled with acid potting mix.
Gardenias prefer regular substantial watering, but they also need moderately well-drained soils with plenty of organic materials worked in before planting. Equivalent to the Rhododendrons and Azaleas, the Gardenia does best in an acidic soil. The root system is shallow and sensitive, so a thick layer of mulch to control weeds is better than cultivating.
Pinching out the tips while the plant is dormant will cause the plant to become bushier. Pinching usually promote heavier blooms the following year.
Gardenias are sensitive to high salt levels in the soil which results from using hard water and fertilisers. To prevent salt buildups, do not over fertilize and periodically leach the soil with rain water to wash out excess salts. Gardenia plants require to be fed through spring, summer and autumn with Azalea & Camellia food.
GARDENIA PESTS & PROBLEMS
One of the most ask questions about Gardenias is the yellowing of older leaves in late winter and spring. This is usually a sign that the plant is moving its magnesium to the new growth. In the beginning of spring feed with Epsom Salts (Magnesium sulphate) will usually solve this problem.
To avoid getting other nutrients out of balance, only apply Epsom Salts no more than once a year.
Gardenia plants that are healthy will grow vigorously and are less likely to be affected by fungus problems. Planted in an ideal position, kept mulch and well fertilised regularly, will help most gardenias to stay robust. Always keep a close examination of the plants and deal with problems as soon as they materialize.
PEST TO WATCH OUT FOR
Scale. White wax scale is usualy the most common form. It's seen as rounded humps with waxy coverings and is often accompanied by sooty mould, a black sooty coating which spreads over stems and leaves. Spray with a systemic chemical or a specific scale spray to control these pests.
Thips. They are tiny black insects which infest the flowers in late spring and early summer, causing the petals to turn brown at the edges. To control spray the plant when the the flower buds are forming with a systemic spray.
Holes in the flower buds. Caterpillars eat holes into gardenia buds and this often causes the buds to drop prematurely. Most often their blemish is not noticed until the damage is done. Sometimes it's advantageous to go out with a torch at night to catch the grubs in the act. Spray with pyrethrum spray or Carbaryl spray to control the caterpillars.