Some hill country land just isn't suitable for farming. In some places it erodes away, while in others the amount of pasture it produces simply isn't worth the cost of fertilising it.

In areas like those around Lake Taupo, where land use and its effects are being put under the microscope and capped, some farmers have found they don't have a choice when it comes to retiring hill country.

Well there's always good old P.radiata, but plantations don't have much of an understorey, leaving soil exposed and at some stage, harvesting them would not be at all nice for the environment.

So why not natives? Well everyone says they grow too slowly, the seedlings cost a lot, not all nurseries produce good quality plants and if the weeds get away they can disappear.

The process required some different thinking, so the Lake Taupo Protection Trust got Tane's Tree Trust, working in cahoots with local landowners, Opus, Scion, Future Forests Research and the Waikato Regional Council, to set up some trials in hill country around Waihaha, on the western side of Taupo.

First they trialled growing a variety of shrubby natives, with some in polythene planter bags, some in root trainer pots and some grown in the open, to be transported as bare rooted plants. Not only did they study how well each species took to its surroundings and grew upwards and outwards, but they also carefully costed the whole operation.

When the time came to move the nursery-raised babies to their hill country location, there were quite large differences in the costs of transporting them. Comparing how many could be transported in a 1m3 space, they found they could get 800 open ground plants (three layers of boxes), only 120 bagged ones (two layers of trays) and 720 in root trainer pots (two layers of baskets).

When they arrived at the planting sites they measured how long it took to plant them out. The bare rooted ones needed to be done sooner than the others, before they dried out. Each person planting could handle 50 at a time and each one took 0.9 minutes to get in the ground.

The bagged ones were chunky and each person could only take 12 at a time and they took twice as long (1.8 minutes) each to remove from the bag and plant. The root trainers could be carried in a basket containing 48, but they too had to be removed from the pot and took 1.6 minutes each to plant. By this time, each plant had cost about $1.10 for open ground and root trainer pots and $3.40 for the bagged ones and in the first two years of the trial they grew at the same rates.

The trial aims to plant podocarps among the shrubs, once the shrubs have provided sufficient shelter. They are still facing a measure of weed control round the seedling shrubs, however and this year's trial plantings will explore different treatments for this, as well as a range of site preparation treatments.

If the thought had occurred to you that sowing kanuka seed might be easier and cheaper all round, well the jury is still out. On one research site in the first year none came up and in the second only a few, despite help from herbicides, different cultivation and even spreading some kanuka duff containing mycorrhiza, although they had slightly better results on some other sites.