Jackie French: How to kill a tree with kindness and good intentions

The main enemies a tree has to contend with, says JACKIE FRENCH, are the humans who plant it and then, with the best intentions, love it to death

The easiest way to kill a tree is to neglect it, right? But trees have survived for a long time with no human help. At least half the trees that are doomed in a garden are killed by too much love, not too little.

1 TOO MUCH TUCKER

Guilty. I killed my first grapefruit tree by overfeeding it. Citrus are hungry, aren’t they? But they also have shallow roots that can be burnt by too much fertiliser delivered all at once. Never apply fertiliser on dry soil, and always water fertiliser in well, and make sure you have the hose ready.

2 THE HUSBAND & THE WHIPPER SNIPPER

I admit the sexism here, but the great ‘over-snippers’ I have known have all been men, neatly trimming the grass around each tree – and leaving small (and sometimes not so small), deadly wounds on the trunk where moulds and other disease-causing organisms can enter. You may not see the tree die back for years if the rot is moving slowly. But one branch and then another will die… and, finally, the whole tree will perish while the whipper snipper is sitting innocently in the shed and the whipper-snipperer reclines on the sofa.

3 THE KILLER MULCH

I mulched a whole row of young citrus once with old carpet, a perfect way to keep the moisture in the soil. It was also a perfect way to keep moisture out of the soil each time it rained. They died six months later. Beware of mulches that compact, such as lawn clippings. Mix with bulky, irregularly shaped autumn leaves or straw or lucerne or sugarcane mulch – anything light and airy so that even a small rain shower can contribute some moisture to the soil.

4 DRY, DRY, DRY…

Gardens are surprisingly drought-proof once they are well established. They may wilt or even turn brown but they will grow back again. But only when they have had time to dig their roots deep into the cool, damp subsoil. If they are shallow-rooted, like citrus, or potted, then a prolonged dry means dead trees.

5 WET, WET, WET…

Be especially wary of trees that are planted in the middle of green lawns. You water the area often to keep the grass green – and the tree develops shallow roots. Why bother heading down? Then in a big wind, with wet leaves… whump. It’s fallen on the car. Or worse.

Too much watering where the soil isn’t well drained can also leave plant roots in a swamp below the ground. If you’re on level, heavy clay or shale, try creating above-ground gardens, or plant shrubs that can cope with wet feet for a while.

6 THE OVERZEALOUS PRUNER

Many humans love to prune. It’s a primitive desire to tame the jungle. But every time you prune, it’s basically surgery for trees – an opportunity for infection. Prune as little as you can – I don’t mean minimally prune, just always think: is this necessary? Cover large cuts with a fungicide paint, and for ‘little and lots’ pruning, prune in summer when the cuts will dry fast and the wounds heal over.