Garden Guru: Back to basics

A groomed topiary specimen looks great beside loose, bold-leafed forms. Photo / Supplied

Looking out on the garden, evergreens have the most telling presence at this time of year, and their position and shape can make or break a good design. That's why it's a good idea to give them a seasonal WOF while their outline and position in the grand plan is more obvious.

It's easy to get complacent and take your backbone planting for granted - it's part of the furniture, after all - but that furniture could date from the 70s and be in need of a drastic overhaul.

Take each major evergreen element and give it this five-point critique to see if it's up to the job.

Is it doing a useful job?

Many evergreens are sensibly placed to hide something all year round, be it an awkward corner, a dustbin, compost area or simply where different fences on a boundary come together in an unsightly jumble. These specimens earn bonus points at the outset and may be worth keeping, even if they are as ugly as sin.

Is it too big/fat/thin?

In frost-ridden areas, it's getting too cold to be clipping evergreens - but you can plan where you intend to reduce, thin or trim to keep each in scale with what you want to achieve.

It's not just pencil-thin conifers which put on a beer belly without you noticing - most shrubs swell sneakily behind your back and, before you know it, are lurching over paths and hanging around gateways just waiting to shower you with raindrops when you brush past or snag the handles of the wheelbarrow, mower or bike.

It's all too easy to grab the shears or hedge-cutters and end up trimming everything into dense blobs. But by thinning foliage instead, you create much more relaxed and healthy-looking shapes which will usually produce more flower and contrast nicely to any clipped forms you may have. Get into the habit of pruning with secateurs and loppers rather than using shears on everything.

Does it relate well to other evergreens?

Because evergreens stand out - especially at this time of year - they need to look comfortably arranged; neither dotted about singly nor, at the other extreme, lumped together in one indigestible mass.

It's useful to imagine them as groups of people chatting in twos, threes or fours and varying in height and form. There is room for single specimens, but try not to have only one of everything, as it can make the garden look busy and restless.

In addition, each shape needs to set off its neighbours. A groomed topiary specimen, for example, contrasting with a loose and bold-leafed puka, camellia or rhododendron.

Put ferny foliage beside glossy and the strong uprights of pencil conifers alongside shrubs with a rounded or strongly horizontal form. Coloured and variegated foliage is most effective used sparingly to add a highlight rather than to overplay the drama.

Is it healthy?

I visited a couple who run a bed and breakfast the other day. As soon as I pulled up, I had to quietly pick up my jaw up from out of the gravel. In contrast to the cheering efforts of their planted containers, right outside the front door stood a golden macrocarpa clinging grimly to life by a thread.

Like many conifers, it had gone bare at the ankles, but to add insult to injury, it had been chopped back brutally at the top and side. The gaping innards meeting you on the front path amounted to coming face to face with a plant pulling a botanical "moonie".

No doubt the owners lived in hope that the wounds would heal, but you don't lop off an arm and expect it to grow back. Most conifers (and ceanothus, cistus and members of the proteaceae family) refuse to refurnish if you prune them too hard.

The fir tree was history and had to go. People are terrified of removing things - they see a space as a disaster rather than an opportunity, but often it's better to be left looking at nothing than having your eyeballs mauled by something half-dead or deformed.

Hebes, corokias and pittosporums are ever-popular native shrubs, but they are often planted up against other shrubs or in shady corners and, as all of them need maximum sunshine, they often go bare. In summer, this may be fine when other plants hide the blanks, but it's in winter that we need to take a hard look at any gaps and ask whether it's time to put in a more shade-tolerant evergreen.

Is it the best plant for the job?

There are a lot of perfectly okay, but drab and pedestrian, evergreens out there. If a particular plant doesn't have especially effective foliage and doesn't contribute to the garden in other ways - say through producing flower, fruit or scent - then you may be doing everyone a favour by creating a space in which to do something fresh.

Many old-timers not pulling their weight can be simply bow-sawed off at the ankles and the roots left to rot away naturally. A few will try to regrow, but that might give your plant a second wind.

If your planting is doing an important job of hiding an eyesore - even if it fails its WOF on some of the other points - it may be worth having work done and money spent on it rather than having to buy a whole new model. A feed, a trim and a tie-up may be all that's required, but the only time a boring evergreen is worth keeping is when its parked between you, a busy road or the view into next door's kitchen window.

Could do this week

* Use strong twine or stockings to pull in the fat waist of neglected shrubs. First prune out a little of the central growth to allow space, before tying outward-leaning branches to a corresponding stray on the opposite side of the bush. With careful tying, you will be able to hide most of your new drawstrings.

* Sarracenias are the easiest of the carnivorous pitcher plants to grow outdoors. In colder areas, bring them into a cool greenhouse, cut them to ground level and reduce their watering to almost nothing during their winter dormancy.

* Finish ordering bare-root fruit and roses. Keep the roots moist when they arrive until you intend to plant.

* Feed auriculas, violas and pansies with dried blood, which encourages prolific
flowering.

* Bromeliads can really come into their own in winter in mild areas - keep their funnels clean of debris and fallen leaves so the colours of each can glisten.

* Try some hardwood cuttings about twice the length and the same thickness as a pencil firmed up to their middle in a sand-filled trench. Hydrangeas are incredibly easy, but other shrubs to try include magnolias, viburnums, wisteria and weigelia.