Garden Guru: Mind the gaps

Spring planting. Photo / Supplied.

Oil your bearings and pump up your tyres, because it's time to move on out. With the soil getting a little moister and plant roots still wide-awake, this is the perfect moment for planting.

But before you throw your wheelbarrow into high gear, be warned that moving plants around the garden will always be something of a juggling act. I had my fingers burned just last week when I adopted a new Japanese maple.

It would be nice to say I had a gap in the border and had been carefully pondering what would look best in that particular hole for months but no, I just couldn't resist a bargain and am a sucker for anything with a bit of classy architecture.

It was an impulse buy and, on getting it home, I needed to figure out what could be moved to create a gap. Good gardeners never have gaps unless a freak tornado or runaway truck has careered through the garden.

The odd plant, of course, will die. Some die slowly because their feet are too wet or too dry or they find it too hot or cold, but a fair proportion of plants (and no gardening book will tell you this) die for no particular reason at all. Perhaps they take a dislike to your curtains, tire of their neighbours or are nibbled by some microscopic virus. Who knows - but the gap they leave is always welcome; an opportunity for change and a trip to the garden centre.

Maples are elegant critters and need shelter from wind and midday sun, both of which scorch the leaves, so my choice of site was limited. Shelter doesn't mean deep shade either, for then the purple leaf colours tend to slide into murky khakis. What was needed for this particular newcomer was a corner catching morning or afternoon sun, but not both.

Maples are also like hebes, lavenders and proteas - as well as a host of Mediterranean plants - in that they don't like to be crowded. So a promontory on a corner or out on the bend of a border was called for.

But after an hour of wandering and pondering, when I finally found just the spot, I also found a formless philadelphus already ensconced in pole position. Shrubs like philadelphus, with lots of fibrous, shallow roots, tend to move quite easily (just dig a good trench right around before you begin any manic levering), but where to put it? I wanted to hold on to it - not for looks, but for its scent and decent flash of white in spring - so it went to a less glamorous home; the back of a border behind the scenes to allow the maple to shine up in front.

To find the ideal spot, of course, a lesser shrub might have to be binned, so you buy one plant and end up digging five holes while the wheelbarrow zigzags around the lawn.

This shuffling is sometimes, but not always, a result of bad planning. Plants invariably grow in ways and at speeds not entirely expected, and the introduction of tasty new and improved varieties will always force you to alter the pecking order and shuffle the pack.

But at the end of the line there will always be a plant which has had its time. The victims, which end up on the compost or gifted to the mother-in-law, are usually the plants with only one trick up their sleeve.

They may only flower once - like forsythia - and have nothing else about them which appeals - no autumn colour, no scent, not even attractive bark. The philadelphus mentioned earlier almost falls into this camp - lilacs, too, sail close to the wind on the "boredometer", but their scent sometimes redeems them.

What you don't want is to be one of those sentimental plant-lovers who can never bear to throw anything away. Their gardens are chock-full of rejects and has-beens shoehorned in and hanging on to life by a thread - and that really is more cruel than a timely trip to the compost heap or, better still, to the jaws of a hungry chipper.

Planting tips:

* You can recognise old nursery stock by the fact that roots are bursting out of the bag or pot and the compost may be infested with weeds or liverworts. Such stock is sometimes sold off cheaply at this time of year, but be aware that the roots may be congested and spiralling around in a tight ball. Such plants will spend a year sulking before they really recover and you will have to be extra-vigilant with watering. Tease the roots free before you plant to encourage them to spread.

* It's easier on the legs and back to break the ground up with a strong fork before digging a hole. Dig even small holes with a spade as with a trowel it's always tempting to skimp.

* Always dig a generous hole, breaking up the soil in the base and incorporating plenty of compost before you plant. If the soil is on the dry side, pour at least 10 litres of water in and allow to soak away before planting and re-watering.

* Don't dig deep holes in heavy clay; build the soil up instead and mulch heavily.

* Most shrubs of waist-height or taller need at least 2-3m between them and the next shrub.

* When moving established shrubs or trees - especially evergreens - trim back the outer foliage to remove about a third of the leaf cover. If height is important, leave the upper growing tips but trim all side branches. This will reduce moisture loss and put the root area under less stress after replanting.

* Unless it's monsoon season, always water newly planted specimens generously.