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Sure the idea of going into a Hydroponic
supply shop seems to be only for the dope growers, but you can grow almost any plants
without any soil or even soil-like media in a saturated nutrient solution, hydroponically.
This may seem anathema to the organic gardener, but its practical acceptance came about by
demonstration on the Himalian slopes of West Bengal near Kalimpong in India during 1946-7.
The individual, who did more to popularise the art or science of hydroponics, depending on
your point of view, was Sholto Douglas. His book Hydroponics the Bengal System was in its
fifth edition by Oxford University Press in 1975 when I added it to my library and may
still be in print. Douglas would not have had the temerity to claim to have discovered the
technique, but he certainly demonstrated its application on the broadacre as no-one
previously had done. There are, incidentally, lots of more recently written books
available, Simple Hydroponics by AC Sundstrom, published by Viking O'Neil, RRP $19.95 is
the ideal beginners manual with a local bias.
The technique
The principle of hydroponic culture is that while the whole
media is saturated only a small portion of the media in the bottom of the container is
liquid, so that about 80% of the air spaces above the liquid is moist, but only a small
part is saturated. This provides good drainage, aeration and moisture from the
nutrient-rich liquid, so the plants are in growth mode all the time.
Quite simply, hydroponic culture requires that you saturate
a neutral media with a nutrient solution. The media provides drainage and anchors the
roots as they grow. The most popular media is Perlite. Made locally it is light yet has a
high moisture retention capacity. However any of the following are also suitable.
Vermiculite, a fine gravel, clean washed sand, Rockwool/Growool or reconstituted and
recycled poly products which have more recently been used to good effect. The initial cost
of Perlite is worth the outlay, because the product is used again and again, whereas
Vermiculite Grade 3, breaks down and finishes up as a rather slushy mess. On the other
hand if you are trying to grow lettuce at Eucla then the extra water-holding capacity of
Vermiculite is a real plus over gravel, which might be the ideal media at Cooma. Grey
Gravel warms up more quickly in Winter and can push some very early season Carrots and
Lettuce along very rapidly. If using gravel it is best to use a non porous type because
they are usually more inert, so their pH has little or no influence on the uptake of the
nutrient solution. Marble chips are excellent if you have access to a friendly monumental
mason in your neighbourhood.
Fortunately the nutrient used to saturate the media is
commercially available from a plethora of outlets and it is comforting to the average user
that you don't have to be an industrial chemist to apply the stuff. Most require only a
few grams dissolved into some tepid water then added to the hydroponic containers. The
several hydroponic growers I know use the same mixture for all their crops and don't seek
to reconstitute the solution with the elements that have been absorbed. To the chemist
that's the real challenge: to be able to keep adding the chemical compounds at the rates
of usage by the vegetable or whatever else you choose to grow. Mushrooms are about the
only common 'vegetable' crop that you are unable to grow hydroponically. They are a fungi
of course and the chemical compounds in the nutrient will kill them, as you will have
discovered if you grew mushies in your lawn and then fertilized the lawn with chemical
fertilizers.
The nutrient is added in solution to water-tight containers
at regular intervals, say weekly or at the very most in the growing season, fortnightly.
The liquid nutrient can be topped up as it evaporates or utilised by the plants or it can
drained totally at the week's end. In areas with high rates of evaporation or a salty
water supply, such as my friends in Marla have, the concentration of salts gets a bit high
after a week so they drain the whole solution and replenish it rather than exacerbate the
problem with lots of top ups that increase the level of undissolved salts. Curiously most
vegetables can tolerate fairly high levels of saline salts when the media is constantly
moist. It's when things dry out that the trouble starts. The discarded depleted nutrient
solution can be added to any undiscerning soil crop. My Horseradish thrives on the
discards.
One hydroponic system that I favour has polystyrene foam
containers with a PVC tube and a float in the tube that indicates the liquid level. These
are known to agronomists as piezometers and can sum up the situation at a glance.
Site
The containers are best located in the same warm open sunny
aspect as you would cultivate a crop in the ground. The big advantage though is that you
can grow the same crops much earlier in a poly igloo or glasshouse or even outside in
frost-free sites, because the media warms faster than most soils.
The hydroponic advantage
Because there is no soil, there are no weeds, no digging,
no soil-borne diseases nor any need to rotate crops. And there's certainly no cultivating.
These advantages are appealing to the gardener who hates to weed or is limited in any
physical activity. Hydroponic culture also appeals to the gardener who wants total
domination over their labours and for gardeners with limited time to dedicate to their
hobby or indeed limited space in which to practice it.
The taste test
Organic purists may denigrate the taste of artificially
grown hydroponic vegetables, but from my own taste tests they are delicious and if
anything, much larger and certainly more robust than much organically grown produce. There
is absolutely no chemical taste about the vegies and you simply won't believe the size of
root vegetables grown this way.
I've seen show-bench quality parsnips 500mm long and 150mm
thick grown in specially constructed poly sleeves, with no forking. Succulent lettuce and
prolific cherry tomatoes are a breeze in the hydroponic media.
Sowing
While sowing seed is possible the beginner may prefer to
plant commercially grown seedlings. If you choose to buy punnet seedlings, wash the soil
or soil-based media from them, then soak in a diluted hydroponic nutrient solution until
they become turgid, before planting. This assures an instant 'take' and they start growing
without the usual check in growth if planted in soil.
For raising your own seedlings you will need a fine grade
(Number 1) of Vermiculite as the seed raising media. Crops like carrots can be raised in
shallow furrows of Vermiculite laid on top of your Perlite media, so that no transplanting
is required, once the seed has germinated.
Red Beet, Silver Beet and the Golden Beets jump out of the
media when grown hydroponically and even Sugar Peas and Snow Peas thrive.
Asian Vegetables that prove a bit slow in the South, like
"Mong To-e" Basella rubra ,"Rau Munong" or "Water Spinach"
Ipomœa aquatica and "Galangal" Languas galanga , can be grown to
perfection, hydroponically.
Final word on culture
If you are keen to try growing herbs hydroponically, you
might want to dilute the solution used, because most Mediterranean herbs yield their best
flavours when grown fairly hard, with low nutrients. Parsley and Basil thrive on the
nitrogen-rich solution, but Marjoram and Chives are best in a diluted solution. Whatever
your vegetable preferences, hydroponics is certainly worth a try. |
