Friday, August 28, 2009

Planting in a Drought

Isn’t this weather miserable! It’s the hottest, driest August I can remember.
But yes, you can plant trees and shrubs now.
Get them in before the summer’s heat, look after them well, and they’ll reward you with a season’s growth before winter.
First, choose plants with drought-resisting potential - and it’s amazing how many of them there are. The local native plant species of our dry rainforests and scrubs are among the best, cheerfully putting out lush green shady foliage despite years of drought. They have evolved to do this by developing roots which can grow rapidly downwards, to a depth far exceeding the height of the tree’s canopy.
To create a drought hardy plant, you need to get your juvenile plant away from the "lolly shop” - that top layer of soil where "spoiled" plants develop shallow root systems. Don't mollycoddle your plants with surface watering. They grow roots where the water is, then suffer badly when the topsoil dries out.
Toughen your little plants up by teaching them, young, that life wasn’t meant to be easy! You can do this with a watering technique which gets the water down to the root zone and below it, skipping the top layer of soil. Young plants then learn to reach deep, and eventually they’ll find the natural groundwater, becoming quite independent of what is going on in the top metre of soil.
Planted straight from little tubes, these species can survive if you simply dig a deep hole, fill it with water and let it drain away, put well-soaked water crystals in the bottom then arrange the plant with its roots reaching down as far as they’ll go, their tips just touching the top of the crystals.
The roots must be straight. If you think they might have curled around in the bottom of their pots, de-pot them, soak them in a bucket of water( in the shade), and wash the soil off. This treatment will kill Australian plants such as Grevilleas, but rainforest-type plants are perfectly happy to be treated this way, so long as they’re kept wet in the process and the hole is filled with wet soil.
Arrange the soil surface in a bit of a dish so any rainwater will run inwards to the plant, or with a run-off-catching crescent mound, if it’s on a slope.
Mulch well
with organic materials. Think about keeping the soil cool. If temporary shade for part of the day is easy to arrange, do it. Do you have leftover firewood that you can stack to the north and west of the plant?
This may be all you ever need to do.
However, if the weather - particularly this warm dry wind - continues, the plant should be watched for signs of wilting. If no rains come after a month or six weeks, an extra dose or two of water may be needed to keep it alive while the roots are still small. A good soak, leaving water to sit in the dish, will re-charge the crystals so that as the soil dries out again, the plant will once again find itself in dry topsoil but with water deep down where it counts.
Plants treated like this will survive, and grow when rains give them the opportunity.
However, all plants grow much faster if given generous amounts of water at an early age.
For maximum growth on minimum water, a good planting technique is to use a large plastic bottle with a hole in the bottom. Bury it beside the plant as you put it in. Water can be poured into the bottle, where it will soak in below the little plant’s roots, leading them downwards.
If you have heavy clay where the bottle takes a week or more to empty, bless your luck in having such water-saving soil, and put the lid on the bottle to stop mosquitos from breeding in it.
With this technique, nothing whatever is wasted to evaporation. Even mulch becomes unnecessary once the plant’s roots get below the top foot or so of soil. This top soil layer then becomes the mulch.
Rainforest species appreciate a little fertiliser every now and again. Ordinary fertiliser will do. Unlike Grevilleas and some other Australian plants originating in naturally low-phosphorus soils, rainforest plants don’t need special “native” fertiliser.

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