November gardening column: Time to lay down some roots

In her latest French garden dispatch, Cathy Thompson is digging and planting

25 October 2017
By Cathy Thompson

There are, happily, few universal rules in gardening – I’m with the late horticultural author Christopher Lloyd in believing that ‘the best time to do something is when you can see it needs doing’. But November 25 is Saint Catherine’s Day and she always has me spade-sharpening and hole-digging.

The French don’t say ‘A la Sainte Catherine tout bois prend racine’ without reason. But note that they are really talking about deciduous woody plants, not evergreens.

Very soon after leaf-fall, these plants have the maximum concentration of root-promoting hormones in their system. It’s win/win with a November planting. If the ground freezes hard, the plant just sits there, waiting for better times (unlike its evergreen friends, who continue to lose water through their ever-present foliage). On the other hand, if late autumn is fine, root growth accelerates apace with moisture and sunshine.

Tree-planting is a subject that shows irritating parallels with the dictums delivered down by nutritional scientists, always keen to point out what we should and should not be putting on our plates. Our heads spin with their contradictory, ever-changing nuggets of advice.

The controversy starts with the hole: we used to dig round holes a metre deep and as wide. But modern advice is for square holes about three times wider than the root system, but not a lot deeper than the existing roots – harder to mow around, but apparently aiding root penetration at the corners on heavy soil. Break up the soil at the base and sides of the hole with a fork, but there’s no need to add organic matter or grit: modern experts believe this inhibits roots growth beyond the initial planting hole.

I prefer to plant bare-root trees and shrubs. These have been lifted from the ground where they were growing strongly and their root systems pruned slightly. A tree or a shrub in a pot is a bit like an animal in the zoo, stunted by its life of confinement and ill-treated by the nurseryman who never gets round to watering it fast enough on a hot day.

The main bone of contention in tree- planting is the old ‘to stake or not to stake’ argument. When a tree is planted in the ground without a stake, the movement of the wind actually helps to build strength and flexibility into the young trunk. Standard trees that are staked all the way up to their canopy are as fragile as babies and prone to snapping for years after planting.

And so, unless you live on the windiest coastline of Brittany, it’s best to buy supple, small young saplings and plant without a stake. Any loss of size is rapidly compensated by excellent root growth – and where there is a good root system the eager young tree races ahead of a larger specimen in just a few years. Also worth noting that small, bare-root trees are cheaper by far than their older nursery companions. So you can plant more!

The key to planting stability is to firm the soil as you backfill over the roots – do this methodically, layer by layer. If you must have a stake – or if you live on the afore- mentioned windy coastline – a stake which is no more than a third the height of the main trunk at planting, should be inserted to the windward side before you place the tree itself. Try, if you can, to buy rubber tree ties, and check them very regularly to ensure that they never rub and damage the water-carriage system of the plant, which lies dangerously below the thin bark of a young tree.

If you garden in a very hot area, make a little shallow depression at the base of the trunk, like a saucer, to hold rain and any water you might have to apply.
Which brings us neatly to the one remaining tree-planting argument: how much to water in the two seasons after planting? Very heavily, a maximum of twice a week, but only if there is no decent rainfall. Don’t baby your plant – they are like children and grow all the stronger for a little tough love.

And, if ‘tout bois prend racine’, think also of taking hardwood cuttings of your neighbour’s superb climbing rose (with permission, of course!) and increasing woody things like blackcurrants, gooseberries and redcurrants.

Pencil-thick stems of about 15cm make the best cuttings, with a flat base that is inserted into the ground and a sloping cut just above the top bud, to prevent rain-rot. Dig a little trench in an out of the way corner of the garden where they won’t be subjected to continual sunshine in summer. Fill the little groove with very sharp sand or grit (4/6 mm ‘concassé’, as the French call it), then stick your cuttings vertically, so that about 2.5cm is protruding above the ground, firming and watering in. Our beloved blackcurrants and raspberries are a doddle to propagate this way.

TOP TIP If you’ve suffered from box tree caterpillar in 2017, prepare now to do battle next year. You can win, with vigilance. At this time of year the overwintering larvae can be found in cocoons of white webbing spun between the leaves – check carefully, because hand-picking is a useful control. It’s also worth buying stocks of an insecticide based on pyrethrum or deltamethrin in readiness for the spring when feeding begins again. This year some gardening friends found that when they got to their local garden centre ‘the cupboard was bare’...

JUST A THOUGHT What do you think about the fact that neonicotinoid insecticides can still be used in glasshouses in Europe? Do you worry that you might inadvertently paralyse, then kill, precisely the pollinating species that you are trying to encourage? Give us your thoughts at editorial@connexionfrance.com.

Read Cathy’s blog at gardendreamingatchatillon.wordpress.com

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