The Power Company School of Garden Design

I was amused to read about the Powerco School of Gardening in the paper recently. The article was about trees reaching in to power lines and the ongoing problem of property owners planting unsuitable trees. I would not dispute for one minute that this is an issue. Most people have a great deal of difficulty envisaging the eventual size of plants and it is hard to see that a little stick around 100 to 150cm tall will ever pose a threat to overhead wires.

I well recall selling a yellow magnolia to a gardener when they were still very new on the market. I warned him at the time that most of the yellow magnolias achieve a similar stature to a timber tree when mature and that they grow very quickly. When I visited his garden soon after, there was this bare rod (it was winter) planted directly below his overhead lines. I think he subsequently moved it, on my recommendation. If not, Powerco are probably chasing him now.

But the bit that cracked me up were the suitable plants recommended by the Powerco spokesperson. Assuring the reader that there are many smaller trees and shrubs suitable for planting near overhead lines that provided shelter, he cited flax, akeake, manuka, birch, Japanese maple, camellia and hibiscus.

As an eclectic list of plants, this one took the cake. I did not think I would be appointing this gentleman as my adviser in the garden. The flax is not a shrub (it is actually a member of the lily family) and although it may afford shelter, it can also become a triffid in the home garden. Mind you, it will never threaten the power lines. Nor will groundcover ivy. From all our natives, the akeake is not a plant of great beauty and merit, being more of a transitional plant when cleared land is reverting to forest. Ditto manuka, although it has a pretty flower. Many of the birches grow miles too tall and will hit the power lines. Japanese maples are charming but wildly unsuitable for shelter. And exactly which hibiscus was he recommending? The most common type grown here are the Norfolk Island forms which can reach up to eight metres or more if left unpruned.

Best advice from the Jury School of Garden Design is not to plant any tree under a power line. Keep to shrubs and be prepared to prune. And do not plant any medium to tall tree adjacent to power lines. Keep to lower growers like our native puka if you are frost free, smaller cordylines (cabbage trees), the flat topped Japanese cherries like Shimidsu Zakura and cercis (Judas trees). Anything that will stay under five metres easily. Taller trees can get a sway on them in the wind and hit the power lines. A bit of care now can save a lot of inconvenience and expense later.

Don’t believe the heights described on the plant label. There is a conspiracy amongst plant nurseries and retailers which universally under declares the ultimate height. Convention has it that the height described is that which might be expected after ten years (the average life expectancy of a plant in New Zealand) but even then it is often under stated. Consumers would often shun them if they realised how large they can grow.

Best case scenario, of course, is buried power lines. I notice much of Palmerston North has this luxury now and trees are able to grow to their natural heights. Would that we had this situation in more of our area.