The next time you are wrapping up against the cold this winter, spare a thought for the Alaskan wood frog.
During their hibernation period, 65% of the water in their bodies turns into ice. They stay in this frozen state for up to seven months, through temperatures as low as -20ºC. When spring finally arrives they defrost themselves with high levels of glucose, a natural antifreeze.
In the UK, we rarely see temperatures as low as that, but much of our wildlife still hibernates over the winter. And our deciduous trees and shrubs do a similar thing – except in the horticultural world we say they go dormant.
And how does that benefit gardeners?
When a young tree is dormant – in a sort of suspended animation – you can dig it up, remove the soil from around the roots, and plant it somewhere else.
This brings many advantages. The tree will be much easier to move and lighter to transport than a tree in a container. It will not require two people to lift, as it may do with a heavy root-ball or a pot of soil attached. And they are much quicker to plant, because you can put them in a smaller hole.
The same is true for hedge plants
Native British hedging plants – hawthorn, beech, privet, yew and blackthorn, for example – can all be purchased in bare-root form for planting as new hedges or for patching existing ones.
How much cheaper are bare-root trees and shrubs?
Prices vary per species, but you can reasonably expect to save 40-45% if you buy a bare-root tree against a comparable one that’s container-grown. And the savings don’t end there. If you are paying to have your trees planted you can expect it to take less time, possibly use less people and involve lower delivery charges.
So why don’t we plant bare-root trees and shrubs throughout the year?
You can only remove the soil from the roots while the plant is dormant, which in the UK is roughly between the end of November and March. In the spring the plant will come out of dormancy and will need the soil to enable it to grow.
Can you get bare-root trees in any size?
No – the largest bare-root tree specimens I’ve seen available are what is known as Extra Heavy Standard 14/16. This means if you take a measure of the trunk’s circumference at 1 metre up the trunk, it will be 14-16cm. Depending on species this would be a tree of between 3-4 metres tall.
Are there any drawbacks to planting bare-root trees and shrubs?
If you are not planting your trees or shrubs immediately after you receive them, you will need to store them in a frost-free but unheated place, like a garage or shed. If you are not going to plant them for weeks, you should heel them into a storage trench somewhere in the garden. You can see how this is done on this video from the British Hardwood Tree Nursery.
When you do come to plant, don’t set them too deep, and ensure you don’t leave pockets of air around the roots by heeling them in well. A great tip for hedge plants is to prune at least a third from the height before you plant. This will encourage vigorous, bushier growth.
Should I wait until winter to plant some trees or hedges?
It’s up to you, but if you can be patient you can expect to save yourself some money. If you want to establish a woodland or need lengthy runs of hedges the savings can become quite substantial.
And us gardeners don’t mind planting them in the winter. It might be cold out there but, unlike the poor Alaskan frogsicles, we’re never too far away from a hot cup of tea.