Gardening: Time to trim

By Meg Liptrot

It's time to establish the right framework for summer foliage and flowers.

Proper pruning should see your hydrangeas looking like this in summer. Photo / Meg Liptrot
Proper pruning should see your hydrangeas looking like this in summer. Photo / Meg Liptrot

Established gardens require care to keep them looking good, so maintenance pruning is a must each year. Older gardens in particular require restorative pruning, which is usually done in winter.

It is better to do a little often, instead of razing your garden to the ground with over-zealous pruning if your garden has become the land of the Triffids. Pruning hard encourages even more vigorous growth the following year, which is not necessarily what the garden needs, so it should be done in stages.

Summer-flowering shrubs are dormant in winter, so this is the best time to prune. Ensure you don't remove too much. In the case of hydrangeas, they flower on the previous year's wood, so remove the flower stem to a couple of plump buds rather than too far down the stem. To keep the shrub invigorated, cut one or two old unproductive branches right down to a couple of buds at the base of the plant.

Doing this each year will ensure the whole plant is renewed over the years and look its best.

Hydrangeas can be also pruned in spring if you live in a cooler area and get frost, or at the end of flowering in autumn in warmer areas. To completely rejuvenate a hydrangea, you can cut it back hard, but don't expect any flowering until the following year.

July is the traditional month to prune roses. Removal of dead wood (brittle with no living green tissue) and diseased wood (black or mottled stems) is an important garden chore for plant health. Remove inward-facing stems with the aim of creating a vase shape in shrub roses.

Cut to plump outward-facing buds. If black spot is a problem, getting rid of fallen rose leaves from around your plant is essential.

Don't put them in the compost. A light spray with copper is a good idea to combat fungal diseases.

Always ensure you clean your secateurs and other pruning equipment with meths between plants (and large cuts) to prevent spreading disease, and remember that a sharper tool makes a cleaner cut.

Vigorous climbing roses put on a lot of growth each year, so select your main structural stems, remove last year's flowering stems back to two or three strong buds, and the long lanky vegetative stems right back to create good form for next year. If need be, remove one old and unproductive woody stem from the base. If you have strong vegetative stems coming from a recently removed old stem at the base of your rose, select the strongest and tie it down so it is more or less horizontal. This will encourage flowering along the length of the stem and reduces the apical dominance, the tendency to upright growth as opposed to lateral growth and budding. Your cuts should be made a couple of centimetres away from an outward-facing bud, at a 45-degree angle to allow water to run off the cut.

It is a good time to look at the overall structure of your deciduous trees while the leaves are on the ground and the limbs are bare. You can prune to balance the form of the tree and check for broken or rotting limbs.

Leaves in gutters are a pain so check around the perimeter of your house for overhanging branches. It is always best to hire a qualified aborist rather than risk life and limb on a wobbly ladder. For windblown leaf litter there are a few products which will help to prevent gutters being blocked. The Hedgehog (it looks like its name) is easily inserted. It comes in 0.5m to 1m lengths, or get a mesh gutter guard installed.

Getting the professionals to do your tree pruning does have an added bonus - they usually have an industrial-sized wood chipper in tow. You can get them to leave the resulting mulch behind so you have a good supply to add as carbon to your compost or to use as mulch (if it's disease-free). Get them to leave the decent wood and kindling behind too and you'll have a start on next winter's firewood supply.

Care for ornamentals

For overgrown deciduous shrubs such as Philadelphus (mock orange) do restorative
pruning in winter.

Prune a third of the oldest branches down to ground level. Otherwise, prune stems after flowering in spring to outward-facing buds.

Hydrangea: Hydrangea macrophyla (mop-heads) flower on the previous season's wood, so prune to shorten flower stems back to a pair of healthy buds.

Cut out one or two old branches at ground level each year.

Bush roses: Remove dead and overlapping stems. Cut last season's stems back to outward-facing buds.

Remove spindly growth, and one or two old unproductive branches. It's best to aim for a vase shape (open interior).

Trees: Remove dead and diseased wood.

Prune branches away from roof lines and guttering. Remember to check before you
chop. Ring a council planner if you're unsure about tree pruning rules.

Cut no more than 20 per cent of live growth each year, and ensure your tree is pruned in a way which doesn't damage its health or natural form. If in doubt get a qualified arborist.

Search "check before you chop" at aucklandcouncil.govt.nz

Pruning tips

* It's always best to prune on the dry day to prevent spreading fungal spores to fresh pruning cuts.

* Clean pruning equipment with meths between plants and ensure tools are sharp.

- Herald on Sunday

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