Inflation in South Africa is rising continually at about 6.25% per annum, and you only have to go to your local supermarket to verify it. Some seasonal vegetables go up and down such as lettuce and tomatoes but when out of season tomatoes are selling for more than R20/kg and lettuces in January and February are going for more than R20 a head then you know you’ve just seen the signs of inflation, food price inflation.
Here’s something you could do to grow your own needs for fruit and vegetables – especially if you have a fondness for growing things – and you can do that quite easily and inexpensively. Hydroponics is the science growing of vegetables and fruit without soil. So it’s not dirty – well, not like you have to go digging around in the soil and wondering whether that soil is rich enough to give your plants the nutrition they need.
Basically, you dissolve two sets of water soluble fertilisers in two separate buckets of water and then pour those buckets into a nutrient tank that feeds your plants. Your plants are held upright by a growing medium, something that imparts no nutrients to the plants, their only job is to keep the plants from falling over and to keep their roots moist. If the roots dry out the plant dies.
There are many different types of growing media such as composted pine bark, perlite, LECA pellets, sawdust, wood shavings, Rockwool vermiculite, clinker – the list is quite exhaustive. However, you don’t need to be confused by the long list. Composted pine bark is cost-effective, has a pH in line with that recommended for hydroponics and is readily available. You can buy bags of it at your local garden shop or in bulk from Gromor near Cato Ridge or Earth to Earth Organics if you live outside KZN.You don’t need vast tracts of arable land to start a hydroponic garden that will supply you with fruit and vegetables for yourself and family. All you need is somewhere sunny, (therefore preferably north facing) with a slight slope for the water to drain off. You could start with an area as small as 5m x 3m (15m2) and populate it with vertical growing columns that accommodate 6 times the number of plants per m2 than any other system. Verti-Gro is just such a system.
Developed in USA and patented worldwide the pots are modular and fit into one another to form a column 9 pots high. This translates into a stack that will house 36 plants and, allowing for walkways, will mean a plant housing population of 30 plants per m2.
So your imaginary plot of 15m2 would house 15/1.2 = 12 stacks of 36 plants each = 432 plants! (Dividing the m2 by 1.2 is a quick way of calculating how many columns (or stacks) can fit into a desired area). You can do this with a hectare; 10 000 m2 divided by 1.2 = 8333 stacks x 36 plants each = 300 000 plants!
You’ll need to buy a header/collection tank to house the nutrient water, and for a small area of 12 columns a 500 litre tank will do admirably and dig it into the ground leaving 150mm protruding. They are available quite reasonably from Builders Express, Builders Hardware, Build-It or Roto Tank in Port Shepstone (free delivery). Into this you’ll need to drop a submersible pump that can pump the nutrients to the plants. The Chinese make a very good one (as if we didn’t know) called SHIMGE and a 0.25kw submersible will do the job and costs about R1 500 from The Pump Shop in Pinetown.
Recirculating the used nutrient water (known as leachate) will cut down the costs of fertilisers and water so to do that you’ll have to get 12 by 10L buckets (available from The Plastic Shop) and fill them with gravel. The columns are erected on top of the stones and held upright by 2m lengths of 12mm square tubing which you can pick up from a scrapyard or Steel and Pipe in Pinetown if you prefer to buy new.
Now link the buckets to the tank by drilling a hole in the buckets and inserting a 15mm LDPE tube into the hole, with a grommet to stop leaks. Tubing and grommets are available from Controlled Irrigation in Glen Anil. The LDPE pipe does not need to be longer than about 30 cm and should be connected to a 50mm PVC white plastic drainage tube which you connect to the tank. LDPE 25mm feeder tubing can be used to connect the pump to the tops of the columns via arrow drippers and plastic connectors.
The columns will need to be stabilised by tying the tops of the metal centre poles to points on the periphery of your growing area. This can be the side of a house or building on the one side and gum poles inserted into the ground on the other. If you are growing herbs or strawberries that prefer full sun you don’t need to use any shade cloth for their protection. However, if you have monkeys in your area you’ll have to protect your crop with wire, either chicken wire or weldmesh. Tomatoes will need protection from the monkeys and you’ll need to shade them from the very hot sun with shade cloth of 30% or 40% green or black.
It’s a good idea to get yourself an EC meter to measure the strength of the nutrients you’ll be supplying your plants. Salad Greens like about 1.5EC and tomatoes about 2.5EC so bear in mind that with this difference in nutrient strength it would not be a good idea to grow them both together unless you had a dual parallel feeding system with two tanks and two pumps. Alternatively you would have to grow them alternately. EC meters are supplied by TunnelQuip of Pietermaritzburg.
If you feel that erecting your own greenhouse is too much like hard work you can get DaisyFresh, see www.daisyfresh.co.za to build you a gum pole and shadecloth structure tailor made to suit your space, and also supply all the accessories that go inside – see below.