Today, around 20% of our fruit and vegetables are grown hydroponically. All the inputs are controlled (water, heat, CO2) and the plants are fed using synthetic nutrients. Insects are also controlled, in the sense that flowers have to be pollinated in a windless glasshouse. So, in the case of self-pollinating tomatoes, the flowers are vibrated to stimulate pollination.
Hydroponic growers label their produce with pride as hydroponic, as if it were a benefit to offer such totally artificially grown food. The food looks real and is blemish free, like supermarket tomatoes, but should we be proud to label food grown artificially?
For around ten thousand years, humans have been growing food in soil where nutrients have been created as a result of natural evolutionary processes like the decomposition of minerals, plants and animals. The suggestion that hydroponic food could be equal or superior in quality to certified, organically-grown food is both arrogant and unproven.
The best things in life are free
Natural or unnatural garden forms depend on the best things in life which are free! Plants purify the air we breathe, deaden the sounds of the city with their foliage, and take their energy from the sun. All we have to do is understand this biological system and manage it.
The extraordinary process of photosynthesis not only harvests the sun’s energy but primitive life forms, billions of years ago, created the very soil these plants depended upon. The foliage, roots and fibre of these plants all contained carbon compounds that decomposed and combined with minerals from eroded rocks to create our soils.
In our last issue we continued the discussion about plants and their garden worthiness, i.e. appropriateness to a rapidly warming climate as well as to different gardening styles.
Garden worthy trees
For some strange reason Australians, and particularly nativists, have a blind spot towards eucalypts in the discussion about suitable native trees for garden styles, ignoring scores of other native trees from the forests of the east coast (such as the Great Dividing Range which stretches from the Daintree all the way down to Gippsland).
These rainforest trees have proven themselves for over 150 years in all our mainland botanic gardens as outstanding air conditioners, making gardens habitable (Moreton Bay Figs, Red and White Cedars, Araucarias, Hills Fig, Flame Tree and Flindersia australis to name but a few).
Unlike eucalypts, which also have evergreen foliage, our rainforest trees have lush green, rather than khaki-green, coloured foliage and their leaves are horizontal providing a denser shade with summer temperatures 5-8 degrees cooler than those under eucalypt trees whose leaves hang down to avoid the sun.
These trees provide free air conditioners in your garden, and should be included in all future plantings, because summer temperatures are forecast to rise up to 5°C, and well above 45°C.
Many gardeners want to plant ‘the bush’ in their backyards and, of course, that is perfectly fine ... if they accept that they will be creating a hotter summer garden compared to those planted with deciduous or rainforest evergreens.
Both eucalypts and Radiata pines provide lousy shade, but they are downright dangerous on a hot day by, in effect, pumping up ground water and turning it into inflammable, kerosene-like fuel on days over 40°C.