The flowers of the gardenia are pure white and richly fragrant; when in bloom, a single plant can easily fill the entire yard with sweet perfume. The rounded shrub blooms heaviest in early summer, but sporadic blossoms will appear throughout the growing season. As the flowers fade, the lustrous, deep green foliage remains, adding colour and texture to the yard all year long.
How to Grow
The gardenia is a heat-loving, semi-tropical evergreen. As such, it needs sun, warmth and constant moisture to flourish. In addition to these climatic conditions, the gardenia is a heavy feeder that thrives in acidic soils. Monthly feeding with an acid-based, all-purpose fertiliser will encourage flower production and help keep the gardenia healthy.
Although commercial fertilisers are readily available, kitchen scraps are easily transformed into plant food for a fraction of the cost. Old coffee grounds are one of the best fertilisers for gardenias; spread them around the base of the plant. In addition to being an excellent source of nitrogen, the acid in coffee will lower the pH of the surrounding soil, stimulating the roots of acid-loving plants such as the gardenia.
Supplement weekly applications of coffee grounds with monthly fertiliser "tea" treatments. Put 1 cup of rotted manure or aged compost into a cloth bag. Seal the bag and submerge it in 1 gallon of water. Let it sit for three days, then remove the nutrient bag and apply the tea directly to the soil.
When to Apply
Begin feeding gardenias in mid-March; this is when they are coming out of their sluggish winter phase and preparing to bloom. Reapply fertiliser once every four weeks until the end of autumn, when it is time to prepare gardenias for the arrival of chilly weather.
Preparing for Winter
To help heat-loving gardenias survive in cooler conditions, surround the plants with a 3-inch layer of organic mulch. For plants in highly visible areas, choose an attractive mulch, such as miniature bark chips or cocoa hulls. A generous layer of mulch insulates sensitive roots and protects them from the effects of wintry weather. Additionally, organic mulches slowly decompose, providing plants with an ongoing source of nutrients for the duration of the winter.
Signs of Nutrient Deficiencies
While a broad-spectrum plant food, such as compost tea, generally supplies a plant with all it needs to maintain healthy growth, gardenias occasionally may require an infusion of a specific nutrient. Most common nutrient deficiencies produce symptoms that are easy to see. Yellow foliage with yellow veins on green leaves indicates a nitrogen deficit. Yellow, curled leaves with green veins is a sign of iron deficiency. To remedy these situations, apply a 4-inch layer of compost to the surrounding soil in the spring. As it breaks down, compost will add essential nutrients to the soil. For a faster fix, rake 1 pound of blood or bone meal into the surface of the soil; this is an excellent source of both iron and nitrogen. Soil that is low in magnesium causes leaves to take on a bronze colour. Correct this situation by sprinkling 1 cup of Epsom salt around the base of the plant, then adding water.