Gardening: Big trees demand a lot of digging

Matt Kraft and Lepolo Leausa from North Harbour Big Tree Company. Photo / Supplied

Professional planters do it the easy-on-the-spine, no-blisters way.

Having planted fruit trees in our future home orchard a couple of years ago, we were aware of the effort and the not so insignificant pain involved in digging when you have a dodgy shoulder or back that's past its flexible prime.

We invited friends to partake in this initial fruit tree planting, a special way to break new ground and toast with a celebratory glass of Champagne and lighten the load at the same time.

But it was hard work for everyone to dig through a thick mat of kikuyu grass to the earth below, and there's a limit to how many times you can call on favours.

A year later we planted a number of large native trees on the south boundary of this former farmland.

Some specimens came in potting bags the size of half-barrels. Rewa rewa, kahikatea, tanekaha, puriri and a kauri, plus smaller pioneers such as manuka, karamu and red matipo were chosen to provide shelter for our bare, exposed site.

This time we hired a post-hole borer to speed up the process. A day ensued of frustration and hilarity, wrestling the giant drill on wheels whose kick-back when being unstuck from clay was so great it threw my husband off his feet.

After all this effort we'd only dug three large holes by the time the machine was due back at the hire centre.

A decent upper arm and core work-out ensued as even more digging was required to loosen the base and square off the sides. This involved sitting on my backside with spade in hand.

Matt Kraft from North Harbour Big Tree Company. Photo / Supplied

Native trees can grow slowly, and to provide immediate shelter, this year I've chosen some faster-growing exotics, settling on Italian alder and Mexican evergreen alder, which are nitrogen fixers, and a West Himalayan birch for its beautiful white bark. We've kept the alders well away from the house site as their roots can be invasive.

We bought (with a twinge of guilt which soon passed) an added extra, to have each of our four new trees planted by the pros at North Harbour Big Tree Company. The trees arrived the following week with Matt and Lepolo, who got the holes dug and trees planted with seamless efficiency.

Stakes were sledgehammered with ease, the guys wielding staplers like hired guns to secure the trees with woven horticultural strapping. Like magic, several 3m-tall trees now grace our garden, providing an instant and elegant leafy screen.

Big-tree planting tips

Choosing your spot

• Trees generally outlive the gardener, so choose wisely.

• Avoid planting too close to your house or your neighbour's house. Check for stormwater drains and sewerage pipes and keep well clear - tree roots grow long distances, and some species are invasive, so get good advice.

• Call Vector on 0800 734 567 to check for underground services before you start.

Get digging

• Plant trees in autumn or winter. This year's El Nino weather pattern is likely to give cooler temperatures, and drier conditions to the north and east of New Zealand, and increased sou'westers. So get trees planted soon then stake and mulch well.

• Dig square holes, a round hole can cause roots to grow in a circle and eventually strangle the tree.

• Loosen the soil in the base of the hole by levering a fork back and forth to improve drainage.

• If you have heavy clay soil, incorporate gypsum and cut a channel on the downward slope to allow water to flow away from the hole during high rainfall. Test your soil pH and find trees that suit your soil and site's conditions.

• Make the team at ACC happy - use a back support belt.

Off to a good start

• Incorporate slow release fertiliser and a little compost in the soil mix. Organic options include basalt rock dust, or a mixed fertiliser from Environmental Fertilisers or Agrissentials (these may include seaweed or fishmeal, beneficial micro-organisms and rock dust) or use a pelleted option.

• If the species of tree you've chosen is prone to fungal issues, add beneficial trichoderma (via Trichopel or Daltons Organic Bio Fungicide) to protect and inoculate tree roots naturally.

• Stake well and brace against prevailing wind direction, but remove stakes in around a year, so the tree doesn't become too reliant on support.

• Use soft woven strapping and gunstaple to thick timber stakes or tie to waratahs.

In time you'll have a sheltered spot for a picnic, and in many years a place to hang a swing or build a hut. You could choose your tree in honour of a special person. Trees should be celebrated - they improve life, for the birds, the bees and people.