The Meteorological Service has recently released a projected forecast predicting the hottest summer in 100 years. Certainly the winter and early spring were unusually dry but now the season appears to be developing normally. Only time will tell. Just in case, here are a few suggestions for the serious gardener who doesn't want to take any chances.
Mulch all susceptible plants now. Especially vulnerable are trees and shrubs with shallow roots like azalea, camellia, and rhododendron and anything planted this season that will not have a chance to establish a deep root system. Be sure the ground is deeply moist before laying on the mulch. Dry areas should be artificially soaked several times.
A great time to do this is just before a rain as the natural rainfall will keep the soil moist longer while pushing the water ever deeper into the soil. It is better to give the garden a long, deep soak rather than several light waterings. Light watering does not sink in which encourages the plants to create surface roots which will ultimately make the situation worst as the ground dries out later.
Dig in copious amounts of compost and peat. These are highly moisture retentive soil additives. Feed the garden regularly and perhaps a bit on the heavy side now with a complete, balanced fertiliser. Special applications of potash (sulphate of potash or wood ashes), phosphorous ( superphosphate, phosphate rock, banana tea or skins), magnesium (epsom salts), trace elements, and blood and bone are all reported to help plants become more drought and heat resistant. Feeding helps create stronger, healthier plants with deeper root systems that would have a greater natural resistance to inclement weather and disease.
Perhaps most obvious is to plant species that naturally enjoy hot, dry conditions. Fortunately, many of our most colourful summer flowers are native to such regions. Zinnias and marigolds are native to Mexico where summer conditions couldn't get much worst. They thrive in the heat and sun providing a riot of colour for many months.
They come in a wide variety of shapes and sizes. Tiny Petit Marigolds and Creeping Zinnias often grow less than 15 cm. Persian Carpet Zinnia with showy star-like flowers, Tom Thumb Zinnia, and the large-flowered Galore Marigolds are under 30cm. While State Fair Zinnia, Dahlia Flowered and Gold Medal series can tower to 1.5m. While most are very bright, they are now available in separate colours include white, pale creams, and soft yellows in both species. Zinnias also come in mauve, soft pink and salmon as well as the traditional brighter shades.
Other tall growing heat lovers include:
Mexican Sunflower (Tithonia), American and Russian Sunflowers, Rudbeckias and Coneflowers, Cosmos, Amaranthus in many forms, Strawflower, Gourds, Morning Glory, and some Chrysanthemum species.
For dwarfer colour try Petunia, Portulaca, Verbena, Alyssum, Gazania, California Poppy, Phlox Drummondi, Swan River Daisy,
Celosia, and Geranium. All guaranteed even in the heat!