Gardening: It's worth the effort

By Leigh Bramwell


Gardening used to be so simple - at least it appeared that way when my parents did it. They planted things, which either grew or didn't, and those that didn't were replaced with other things.

Vegetables were planted every spring. They grew, and we ate them. The orchard produced fruit, and we ate that too, although fruit from the neighbours' trees tasted much better, especially when pinched after dark.

I'm sure my parents knew nothing about pH and I'm equally certain they never spent an hour and a half in two hardware stores and three garden centres searching for the perfect soil pH testing equipment.

But when The Landscaper gets a bee in his bonnet about something there's no stopping him.

He bought a complicated soil probe to test the soil and find out why certain plants are turning yellow.

He's had sleepless nights over a client's gardenias, and our port wine magnolias, which are green on one side and yellow on the other, have also been causing him some angst.

The problem is, he explained in an attempt to justify his substantial spend on the soil-testing kit, is that soil is not the same from one area of the garden to another. What is acid one day may become alkaline the second your back is turned.

There is a definite limit to how much I want to know about soil pH. However, I concede that it is important to the health of your plants because it affects the availability of nutrients in the soil. Many plant nutrients are not readily available to plants in highly alkaline or acidic soils. Most horticultural plants grow best in soils with a pH between 6 (slightly acid) and 7.5 (slightly alkaline). If you have pH problems - and yes, it is best to do a soil test to find out - you choose either plants adapted to your soil's pH, or alter the pH to fit the plants.

If you have a gang of mature port wine magnolias that are languishing you may decide, as we have, to go with the latter.

If your vegetable plot is overly acid but you are not sure to what degree, it's best to adopt a cautious approach to avoid the possibility of over-liming.

Apply a dressing of garden lime or dolomite at the rate of 180g a square metre. One adult handful is about 100g.

Spread the lime on the surface and leave it to be washed in by rain or irrigation.

Liming benefits clay soils and other heavy soils as well as loams and acid sandy soils. Add it before growing. It's best applied in warm, moist conditions.

More difficult is making a lime-rich soil neutral. You can try mixing finely ground sulphur (often sold as flowers of sulphur) into the soil with a bucket of partially rotted pine needles.

Fork in a bucketful for each square metre and also build up the humus content of the soil with manure and compost, particularly leaf mould.

Not all plants want the same kind of soil. Even within the vegetable kingdom you'll find variations, with most vegetables doing best in a slightly acid soil with a pH level of about 6.5.

But some, including brassicas, beans, onions and asparagus, demand nearly neutral soil.

Strawberries and potatoes want acid (ph 5 to 6, thanks), fruit trees and bushes require a neutral or slightly acid soil, and figs and grapes a slightly alkaline one.

Not exactly straightforward, but at least you'll get your money's worth out of your soil testing kit.

Consumer Institute tests show that some pH testing kits and meters don't give accurate readings. Soil-testing labs can give much more reliable results, but that will cost more than a budget kit.

- Hamilton News

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