Creating a sustainable garden

A sustainable garden will ensure you and your plants are not left high and dry.

By Lee Ann Bramwell

About a zillion years ago, I was given a book called The Dry Garden by Jane Taylor. Living in Dunedin at the time, I had no real idea of what that actually meant, since it seemed to me that the number of days without rain – summer or winter – could be counted on the fingers of a sawmiller’s hand.

Now, living in the Far North, I know as much about dry gardens as I do about wet ones, since we swing from drought to flood with alarming regularity. It makes planting a sustainable garden a task best suited to a necromancer.

We seem to be having a wee drought as I write this. Today is Friday and it rained for the first time in weeks on Monday, delivering an acceptable 60ml (guess who got a rain gauge for Christmas) and resulting in the emergence of several split tomatoes and a fresh crop of weeds.

But nothing has fallen out of the sky since then, the cracks in the lawn are big enough for the lawn mower to go down and quite a few new shrubs are pretending to be ground covers and lying flat on the soil.

So I’m now reviewing certain areas of the garden with a view to making them more sustainable, whatever the weather. To achieve this, you need to divide your garden into water-use zones based on what is planted where, and designate each area a low or high frequency irrigation zone.

Then try, over time, to turn most – maybe 75% – of your landscape into a low water-use zone. It doesn’t mean you can’t have any thirsty plants – just plan small areas where you can grow those favourites that drink like fish. Move the heavy drinkers currently in low-water zones to a high one so you can start the rest of the plants on a programme of less-frequent irrigation. And then:

1) Improve your soil. Add organic matter and try to mix in to a depth of about 25cm. Around woody plants, especially long-established ones, you’ll probably have to layer it on top of the soil.

2) Mulching around permanent planting is a good way to conserve water. Where you next turn the soil over, use compost, lawn clippings, straw or leaf mould which break down quickly when buried.

3) Train yourself to irrigate no more than is necessary. If there’s no significant rain, about 3cm of water once a week should be delivered to high water-use zones (unless the area contains seedlings). For low water-use zones, once a month is ideal. Your plants will have to adapt slowly to the new regime and you’ll need to watch for drought symptoms. To keep evaporation to a minimum, water when temperatures are cool – early morning and evenings are best.

4) Buy good irrigation equipment and use and maintain it properly. You need to be scientific about this if you want to save water. Consider installing a drip irrigation system or using soaker hoses in your beds. If you’re on tank water and you have an electric pump, you’ll save power by irrigating everything at once, rather than watering areas consecutively.

5) Install rain barrels wherever you have down pipes. The garage and the shed will contribute something to the water collection, even if it’s only enough to water the pot plants.

6) If you haven’t enough water to support a big pond or swimming pool, choose a re-circulating water feature or a plunge pool. Even a spa pool can be converted to keep you cool in summer.

7) Rationalise your vegetable garden. You may find that intensive techniques will give you good production from a smaller space.

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