Gardening in the north

Living up north means there's not much time for gardening. Not because one is too busy but because the summer is too short. The growing season 2012 here started on the 8th of May and ended on the 15th of October. Growing seasons are expected to become longer during this century due to climatic change, but I'm not sure if that's something worth celebrating. I'm actually surprised to know that the growing season has been a good 5 months, because it really feels more like 3 months to me.

The place where I live is just as north as southern Greenland or Alaska. Let's face it, this is far too north for gardening in most parts of the World. But thanks to the North Atlantic Golf current, the weather here is not as cold as in Siberia. I actually live in the European hardiness zone 4 or the Finnish growing zone 5.

You can find this map and learn more about hardiness zones at the Free Independent Sun.

Apparently this means that the average annual minimum temperatures here are between -28,9 / -34,4 °C or -20 / -30 °F degrees. February usually is the coldest month of the year, and even though this year has been mild, last winter was not. I can grow various plants up here, that manage to survive the winter, but don't bloom. I can also grow plants, that don't only survive the winter, but bloom as well. However the growing season is too short for them to form seeds. 

But the survival of the plant does not depend only on the length of the growing season or the average minimum temperatures alone. You can look for a spot where the microclimate is suitable for a certain plant, like a warm spot close to the southern wall of your house with plenty of sunshine and with protection of winds. But the protected spot can be hazardous in winter, when snow falls from the roof and breaks the branches of the tree. This place might be perfect for some perennials though. But there's not much snow close to the wall either, so there no snow cover to protect the ground and the roots.

Some plants that usually are afraid of cold, may do well under the protective cover of snow. The parts on top of the snow may get frozen each winter, but the parts below the snow stay alive and continue growing the following summer. Of course this means that the plant will never grow too large or maybe not even to the height you were hoping for. There's no point planting a tree and expecting it to do well under these conditions though. It may stay alive for a few years, then get tired and eventually die. Usually they don't survive the first winter. Another problem occurs every now and then; this winter the freezing temperatures of -20 °C degrees arrived before the snow. So there was no protection for the plants before the cold cast its spell over them.

Frost heaving is one problem more. Plants can't start growing before their roots are free of frost, not even if the temperature of the air is nice and warm. This is why evergreens may die during their first winters especially if they have a shallow root system. When the sun starts heating the air early in the spring and their leaves start evaporating, the plant dries out because the roots can't get any water from the frozen ground. That is why it's advised to protect these plants from the spring sun or maybe moderately water the ground with warm water to make it melt faster. I have some Rhododendrons growing beside my front door, so I have been shovelling snow on top of them to keep them protected as long as possible.

I have planted some less hardy plants in my garden, and I'm not sure if I can expect to find any of them alive when the spring arrives. But I thought I'd never find out if I didn't plant any of them. Who knows what kind of a surprise they will offer! I have been told that magnolias can't be grown this north, but I have read that there's a specimen of Magnolia x soulangeana growing in the botanic garden of the Oulu University, and that it has survived. I have been informed, that Malus purpurea 'Kadetti' can not be grown here, but I have seen one growing in front of an apartment building, and surviving several winters already. I have also been told that Taxus can not been grown here unlike the one I just saw the other day.

Of foreign plants we tend to favour Canadian cultivars here because they are usually good and proven and survive the winters well. We grow Canadian crabapples, blueberries, roses and what not. Also Russian cultivars do well over here; plums (Prunus domestica) and honeyberries (Lonicera caerulea var. edulis) for example. Of course we have our own local cultivars as well. I have a damson plum (Prunus domestica subsp. insititia) 'Silvast' in my garden, several Finnish roses like Rosa pimpinellifolia 'Ruskela', Rosa majalis 'Tornedal' and Rosa pimpinellifolia 'Juhannusmorsian' and a sour cherry (Prunus cerasus) 'Arttula' as well as Finnish Rhododendron cultivars. But surprisingly many garden plants originating from milder climatic conditions can be grown over here as well. Peonies are a good and bold example among them.

Rhododendron 'Helsinki University'

I'm a hardiness zone stretcher myself, so I plant anything that could be even remotely hardy in the local conditions and just see if it survives or not. Oh, don't tell me they're all going to be dead when the spring arrives! I won't even listen to you. If they show no sign of life before the autumn arrives, then maybe I will consider them dead. Or just well dormant.