I've was watching a video on viticulture the other day when the TV picture jarred to a still and the presenter said, "Let's just watch that again." We went through an action replay of the vineyard owner showing us what a fruiting spur looks like. The presenter said, "Look how Harry is so quick on the draw." It still took a couple of run-throughs and a big red arrow on the screen for me to spot that while he was talking to us, Harry had whipped a pair of secateurs from his pocket and snipped off a shoot.
It was a Damascene moment. The shades were lifted from my eyes. Suddenly I realised that pruning is not about cutting off limbs, or prettification. Pruning a grapevine is about increasing quality, creating form and vigour. It is often about decreasing, rather than maximising yield, in order to increase quality. Viticulture is a year round process of tending, not an annual assault.
Three years ago this week I snipped three tiny shoots from a grapevine in France. Now, three years later, my own grapevine, grown from one of those cuttings, is flowering for the first time. I'm going to share with you a few of the things that finally fit into place for me, thanks to Quickdraw Harry.
Phases of Plant Growth
When you start off a cutting or bring home your young vine from the nursery the books on pruning seem extremely confusing. That is because regular annual pruning is reserved for mature vines. What you have is a juvenile and there's a lot of different work to be done before that callow youth will be allowed blossom.
In the first year or two you will need to concentrate on forming the trunk of the vine. This is the bit that will support the growth and grow thick and strong. But now it's unlikely to be thicker than a pencil stem, so it can be trained, bent, curled around a pillar or trimmed to the desired height.
As the stem grows it will naturally start to sprout side shoots. You will need to decide how many of these side shoots or laterals you wish to keep. The fewer you preserve, the stronger the vine. Some pruning methods keep hardly any laterals, preferring to get the grape to grow new ones every year. In other forms, and recommended for an ornamental pergola, it is better to plan to mature few laterals. Then each year the pruning will be easier.
Bending the main stem
The main stem can also be persuaded to act like a lateral once it has reached the top of the trellis or support. It will naturally bend over and can be trained sideways. Similarly you can encourage twin or four stemmed lateral growth, which will give you a bit of insurance in case one of the stems becomes damaged.
These are the final stage of training. The fruiting spurs are formed naturally as a consequence of bending the stems horizontal. The sap rises to the top of the twig, which encourage the formation side shoots. (The same things happen when you train a climbing or rambling rose.). Each of these fruiting spurs will eventually support the fresh shoots on which the grapes will form.
So you now only really have three terms to get to grips with;
All grapevines, however they are trained, will possess these elements to a greater or lesser degree. But there are more pruning forms than three leaf clovers. Some forms have very short trunks keeping the bush close to the ground, where it can benefit from reflected heat from a light soil. Some people cut the laterals right back every year, so the horizontal wood is regularly renewed. Some train the spurs skywards in single or double rows of wires like telegraphy wires. In some forms the fruiting spurs hang downwards.
Choosing a shape
Now that you understand the three parts of the grapevine, you can start to think about its final form. Look at the sketches below for just a few options.
In the garden there are even more. You can fan train a grapevine against a wall, or on top of a tall stem you can form a criss-cross of laterals to cover a pergola.
Even in a pot you can bend the young stem around in every decreasing spirals outlining a Christmas tree shape. Remember the need to keep the laterals more horizontal than vertical to encourage sprouting.
The final form will depend on your taste and on the natural growth of the plant. If the stem bifurcates, as happened with my vine, then go with it.
Forming the framework
Once you have decided on the form, the first few years will be concerned with ensuring that the structure is sound. Remember that the main stem will grow thicker every year, so make sure it is well staked and that the ties are not too tight. Choose laterals carefully. These tend to be gangly in their first few years. If they grow too wippy, trim them back by a third or a half, to strengthen the framework. The laterals can always be extended next year from a new end spur or trimmed right back to let another one form.
Forming the spurs
In the books the gradual progression of tending a young grape through the formation of stem, laterals and spurs is generally equated to three years growth. This is an over simplification. For a start the stem may only really get going in the second year of growth and the transition between stem and lateral is often gradual. However, the formation of spurs definitely mark the the end of the juvenile stage. To form the spurs you will need to be aware of one great truth about viticulture:
THE FLOWERS ONLY FORM ON THIS YEARS GROWTH
No amount of tending, snipping, training or bending will encourage the hard wood of trunk or a mature lateral to shoot, let alone fruit. Hard wood only shoots where it is pruned. The aim is to help the hardwood of stem and laterals to become strong. The lateral, which must always be horizontal or at least angled more than 45• away from the vertical, will form spurs only when it is young. The books talk about stems no thicker than a pencil. That is a useful rule of thumb. Once thicker than this, new spurs will be less likely to develop.
So early on in the life of the lateral we must choose shoots that will form the spurs of future years.
These spurs form naturally from a young horizontal lateral and can be trained upwards, sideways or left to hang down.
I've just pruned my vine to form a spur shoot at approximately 250cm intervals (a handspan) along the lateral, trimming away any growth between these points. This is what many books refer to as the third year of training and for me it has come on the third anniversary of my taking cuttings. This is also the first time I have seen flowers on the vine, some of which have been pruned away in the process of selecting spurs.
It's all about quality
Don't worry if you are cutting away vigorous shoots. Pruning is about conserving the vigour, so that energy is diverted to the fruit and not the bough.
Over time the spurs that I have selected will be pruned back every year. Eventually they will become hardwood nodules, creating that lovely gnarled effect that we see in an old vineyard.
Once the form is established pruning systems change. Regular pruning is done in autumn and /or in late spring, once the threat of frosts is past. Every year each spur will then be encouraged to form a series of new young shoots. Choose two to remain and trim the rest right back. With luck each spur will form two vertical stems and two bunches of grapes on each stem.
But the tending process goes on right through the growing season. In the UK we are advised to cut back any further bunches beyond two per shoot, to cut away leaves that overshadow the grapes and halve the number of fruit on the bunch to ensure full ripening. Similarly at any time in the season a spur might run to wood, creating a long non fruiting arm. That is best cut right back.
This is why I like to use the term 'tending' a grapevine rather than pruning. Tending implies the regular and gentle maintenance that a viticulturist naturally employs. In the video I was watching Harry the winegrower had snipped away at an extraneous shoot from the side of a spur. It wasn't the right time of year to prune. Perhaps he'd noticed some damage. But he'd seen the problem and - snip - he'd dealt with it.
In the autumn, once the fruit has been picked, all of that year’s growth will be cut right back to the hard core of the plant. Fruits will not be born on that wood next year. In winter well trained vines look like soldiers in the vineyard, so regular and rigorous is the regime.
In a home trellis I don't need to be quite so regimented. But the basics of pruning for yield and quality can be seen all across the rooftopvegplot plot. The Japanese wine berry has its old shoots trimmed right away and the young shoots cut back to reduce the wood and ensure that I have fresh young canes to bear fruit.
The fan trained elder, which is doing splendidly, has short spurs from each lateral, and on each one, just like the grapevine, the succulent florets of elderflower are already in bud. The tall, sterile shoots will be trimmed off, unless I wish to preserve one to form another lateral of the fan, bending it down to encourage fruiting spurs along its length.
Even the wisteria will be cut hard back, reducing the wippy shoots that form only leaves, in favour of short vigorous shoots from spurs that form the flowers.