In this post I’ll look at winter pruning of vines from their first through to their fourth year. For this purpose I’ve chosen to illustrate winter pruning of a vine destined to be trained as an espalier against a wall. I will also give some advice on how to restore mature vines that have been left unattended for some time and so no longer bear fruit, or if they do the fruit fails to ripen.

Vines are grown on many different kinds of supporting structures. In my last post I showed photographs of a mature vine, before and after pruning, that has been fixed to a trellis that is typically used in a vineyard. In this post I’ll first  look at how vines can be grown as espaliers against vertical walls. In an urban area, or in a small garden, the south or west facing wall will often be the best place to plant and train a vine. It is sheltered from the north and east wind; if it is made of brick or stone the wall itself heats up during the day and increases both the daytime and night-time temperature; and the wall itself provides a convenient surface onto which to pin a trellis. As long as the vine’s roots can spread out from the initial spot where it was planted and provide the water and nutrients necessary for its steady growth, the vine can be trained as high and as wide as the wall and the wine grower’s steadiness on a ladder will permit.  Just look at the ancient vine in the glasshouse at Hampton Court on the edge of London to see how massive and productive a single vine can be!

ESPALIER VINE

The illustration at the top of this page tracks the annual growth and then pruning back of a vine over a period of three years. During the first year the grower will allow the vine to grow freely. But at the end of its first year s/he prunes it back very hard, leaving only two or three nodes from which buds will swell and burst into shoots in the following spring.

Pruning in the second year

So in the summer of the second year three separate branches or canes shoot up from the pruned vine in our illustration – two canes growing out of the two node spur on the left side and one from the single node spur on the right side. The grower now has a choice in mid season – to prune the vine or to leave it alone. S/he may either simply train these three canes onto the trellis and allow them to grow freely right to the end of the season, or s/he can prune the two weaker and/or poorly positioned canes right back in order to channel the maximum sustenance to one remaining, strongest and best positioned cane.  This single cane will grow very strong.  However, in our illustration above you can see that the vine is allowed to grow freely and completely unpruned throughout the second season. The grower has decided that the vine will benefit overall if it is left alone, and is allowed to carry a maximum number of leaves. The plant is thereby able to store the maximum nutrients in its roots that the leaves produce through photosynthesis, which will increase its capacity to grow powerfully in the following year.

Then, in the winter of the vine’s second year the grower stands back and looks carefully at the vine, at its overall shape and its separate parts. S/he is looking to see how the vine has evolved, and how best to prune the vine for the following season, when it will shoot forward again and occupy new, further outlying space over the surface of the wall.

If all three canes are long and strong one may decide to cut each of them back to their ripe wood, spread them out evenly, say in the shape of a trident, and pin them to the trellis. Or, possibly, the two strongest of the three canes could be chosen to form the frame of the vine for the next year. In that case the weakest and worst positioned cane will be cut back close to its base, leaving only one node on it (as insurance for possible damage occurring later to the other two canes), while the two strongest canes are cut back to their ripened wood and spread out, say in the shape of a V, and pinned to the trellis. In the illustration above, you can see that the grower in fact chosen to retain only one cane, to prune it back and to pin it upright to the trellis.

Retain only ripened wood

Only ripened wood will carry healthy growth in the following season. Wood is ripe when it has hardened and has turned bronze or brown in colour. It will also be at least the thickness of a pencil along its ripened length. The sections of the cane that remain green at the end of the growing season are unsuitable, and pruning is always carried out well down into the region of ripened wood.

Sacrifice grapes in the second year for long term vigour

Some bunches of grapes will appear on the vine in its second year. The grower should pinch out all but one or two of these bunches in their infancy so as to concentrate the vine’s energy on producing a robust growing frame and a strong root system. Two year old vines that are allowed to carry a full crop of grapes (4 to 8 bunches over one to two metres of canes) will exhaust themselves and not recover a normal rate of growth for several years afterwards.

Pruning in the third year

In the spring of the vine’s third year buds will swell on alternating sides up the upright cane (or canes) and then burst into shoots and grow rapidly away from the frame. These shoots thicken into canes. Secondary shoots –  laterals – appear at the interstices between the cane and the stalks of leaves. By mid summer the three year old vine will have covered a substantial area of the wall. The ever lengthening canes will have to be tied down several times to the trellis as they grow outwards.

Very early on in the growing season the embryonic bunches of grapes will appear at the tips of the growing shoots. Usually, they come right after the second leaf. The grower will be able to know very early the potential size of his/her eventual harvest. However, all kinds of things can happen before harvest time to reduce or even decimate the crop.  The care and coaxing of the eventual harvest is a separate discussion, one that is related more closely to summer pruning, not to winter pruning. So it will be taken up later in a new post.

Without even venturing into the issue of summer pruning, let’s go right to the end of the vine’s third year of growth and consider the winter pruning that needs to be done then. Inasmuch as we are training our vine against a wall with wires attached horizontally to it, we are able to shape a vine into a frame with horizontally trained canes emerging from either side of the original main cane- or trunk. These horizontal canes are stacked at evenly spaced intervals up the trunk. This espalier training of the vine evenly spreads out all the growing points of the canes over the entire vertical plane, which means that each bunch of grapes  is not crowded by the others and has ample room to swell and face the sun and take the breeze all around it. Moreover, the espalier being trained over its whole surface at an equal distance everywhere from the wall itself warms the vine evenly over its length and breadth.

Note: the espalier vine on a south facing wall will almost always have a microclimate superior to that of a vine growing ten metres away in an open space. The only disadvantages of wall trained vines, compared to the field located ones, are the possible lack of nutrients and growing space in the ground for their root systems, and the poorer circulation of air around them. However, both of these potential problems can be rectified.

Therefore, at the end of the third year the grower again stands back and carefully looks at the vine, looking to understand how it has evolved over the season, S/he then chooses the strongest and best positioned canes growing out from the trunk (or trunks), cutting them back to their ripe wood and tying each one of these selected canes to the trellis in a more or less horizontal position. This completes the shaping of the vine for its growth in the following years.

As the illustration above shows, the grower has chosen not to make these horizontally trained canes very long. There is no simple answer to the question: how long should they be? Only experience with your own vine will tell you how much fruit it can carry. And so it is best to err on the conservative side when pruning at the end of the third year and to leave a total of, say, 16 to 24 nodes/growing points OVER THE WHOLE PRUNED FRAME. Then the vine will show you in its fourth season whether it has the resources (root system, leaf mass, light exposure, minerals, etc.) to carry fruit on all of these growing points. If it does, you can inch forward and extend its frame even further at the end of the fourth year. Or conversely, you may have to hold on and leave the frame as it is for another season.

If you have created a well balanced and well spaced frame in the first three years, pruning an espalier vine from the fourth year and onwards  is quite easy. First, you may want to extend the arms  – or cordons – of the espalier further outwards once you can see that the vine has the capacity to expand. All you need to do is to retain part of the new cane that grew from the last node/bud along the cordon in the current season and tie it down horizontally to become an extension of the cordon itself.

And second, you will be pruning the growing tips along each cordon. Rather than laying down new horizontal canes from the main trunk each year (this is called cane pruning, more on this method later), you can simply keep your existing cordons and prune them at each of the growing ponts along their length. The photographs below shows this method, which is called spur pruning.

 Simply cut each cane that has grown in the latest growing season back down to one, two or three nodes/buds. These are the spurs for next year’s growth. It is preferable to make spurs from canes that are facing upright  or at least sideways, and to cut off completely those canes that face downwards.   So, at the end of the growing season you will have pruned away at least 90% of the season’s new wood, leaving behind only as many nodes on spurs of the new wood as are needed to start the next season’s growth.

OLD VINES IN NEED OF RESTORATION

I have walked around the streets of North London and noticed big and dense vines spilling over walls and fences. They have been left unattended for long periods of time, sometimes for years. In the spring the new shoots come out all over the surface area of the canopy, followed quickly by embryonic grape bunches. Underneath this sprinkling of bright green foliage there remains an impenetrable dense tangle of trunks, branches, long trailers and dead leaves. By the end of June, powdery mildew begins to attack some of these vines and the swelling bunches of grapes turn grey and stop growing. The grey coloured mildew spreads to the leaves. Other such untended vines don’t seem to be affected by mildew and they carry their grapes, albeit in small bunches, through to ripening. Still other vines never seem to show much fruit, if any. Perhaps they are not meant to bear fruit. Or more likely, these vines give up all their energy sustaining a mass of wood and leaves, and have nothing left for fruit.  Which confirms the saying that its is easy to grow a big grape vine, but its hard to grow grapes on it.

If  you have a vine of the kind I describe above and it bears fruit poorly, or it is regularly attacked by mildew in the growing season, it is sometimes possible to restore it to health and productivity. Below I have provided a simplified illustration of such a vine gone wild both before and after a restorative pruning. This illustration can be taken to represent either a horizontally or vertically spreading vine. The rules to apply when pruning it are straightforward:

1. Before you prune anything stand back and look carefully over the vine, its overall shape and its parts. You may have to pull back some of the tangled wood in order to see its main frame.

2. Mark out the frame of the oldest trunks you want to retain (tie a brightly coloured ribbon to each one), ensuring that they are spread or can be spread out over the available surface so as to give each growing point along each trunk ample surrounding space. Then cut out completely the trunks of the oldest wood you don’t want to keep and remove them. Look carefully along each trunk before you cut it off!

3. Going along each trunk of the frame from the ground up choose at roughly equal spaces along it a new cane or a side branch that carries a new cane. This cane should be as close as possible to the point where the side branch grows out from the trunk itself. Now prune this cane into a spur of one, two or three buds, and cut away all the other unneccessary wood – side branches and canes – around the pruned cane you chose to retain.

4. Sometimes you will discover that a new cane grew directly out of an old main trunk in the previous season – you can tell by its colour, texture, and absence of bark that it is the newest generation of wood on the vine. Wherever possible, use this cane to make your spur for next year’s growth.

5. If necessary repair the structure holding up the vine. Sometimes this is best done before the big pruning job, sometimes afterwards.