Printing grape vine always makes me feel like a respectable citizen, indeed. Come to think of it, this is the only gardening operation I have always done on time and rather thoroughly.
Not that I care all that much for grapes which, in any case, the hornets, mockingbirds and so forth usually feast on more than I.
It is astonishing to me how many gardeners ask about pruning grapes, but it does not astonish me at all that the vine is popular, quite apart from its fruit, for nothing is handsomer on a fence, or in woodlands growing up trees, or on arbors or against walls.
The original commotion over grapes is presumed to date from the day it was discovered they could produce wine; but since nobody knows anything about the originial fascination of the grape, despite a good many authoritative sounding statements by anthropologists, I think it equally likely it was the beauty of the vine.
When I was a quite small human, I remember admiring the grape, vines before I noticed they had grapes, and consider it likely my first father was no different.
Recently I have been reading myself to sleep - I have always had the misfortune to fall asleep almost the minute I hit the hay - with a pleasant 140-page discussion on the management of grapes by L. H. Bailey. Possibly my book, "The Pruning Book" (The Macmillan Company, New York 1898), is out of print, but no matter. The nature of the vine has not altered in the last few years so far as I know.
There are one or two cardinal principles of grape pruning that can be understood by anyone, and a great many variations and refinements for those who like to carry on about things.
Let us suppose you have a grape vine that is a great tangle through the neglect of years. My suggestion is to saw it back to its main trunk sometime between now and mid-February, causing it to send forth new branches in the spring. These will not bear fruit this summer, but will form the basis of production in all years to come.If I had such a neglected vine, against a garage, I would saw it down to a three-foot stump.
I would then save perhaps six or eight of the shoots that sprouted this coming spring, intending to cut off all but four next winter, and shortening the four that I kept to four or five feet. The following spring, I would let those four branches bear fruit on the third, fourth, fifth and sixth eyes from the main trunk. And while that fruit was forming, in the summer of 1978, I would let four other branches (which sprouted out in the spring of 1978) grow freely, as long as they liked.
In the winter of 1979, I would then cut off the four branches that had borne fruit, and tie in the four branches that had grown in the summer of 1978 but had not yet borne fruit. In the summer of 1979, the 1-year-old branches that had not borne would be allowed to bear, while at the same time I would allow four new branches to grow as they wished during the summer of 1979.
Here we should pause and state the general principle: Fruit is borne on vigorous 1-year-old branches. Fruit is not borne on branches any younger or any older.
That is why we allow, every year, new branches to grow in the summer.
Because we know that when winter comes, we shall cut off the branches that bore in the summer just past, and we want a supply of 1-year-old branches that can be allowed to bear in the coming summer.
This then is the cardinal point: Keep the new wood coming right along because it is only on the branches that grew last summer that next summer's fruit will appear.
The grape vine, if not tended to, will grow on and on, covering a whole garage in some cases if not interfered with.The fruiting branches of 1976, if not pruned off, will send out new branches in 1977, and the 1977 branches will send out new ones for 1978 and so on forever. But as the years go by, what of the branches (never pruned off) of the past years? They will still be there, not bearing fruit, for they only bear when they are a year old, and usually they will be so thickly overlaid by the branches of later years that they will have no leaves.
Now the grape vine, if not pruned at all, tends to bear fruit at its extremities, not near the main trunk.
The more the growth builds up, over the years, the farther the extremities of the vine are from its roots and trunk, and the less the proportion is between 1-year-old wood and older wood.
The time comes when this enormous mass of vine bears few if any grapes, whereas a vine far older will still be bearing heavily if it has been sensibly pruned through the years.
There is another point: Not only must there be 1-year-old branches for the forthcoming summer's fruit, but the amount of fruit that is borne has a direct relationship to the size and vigor of the vine.
The more leaves a vine has, the more fruit it will bear on its 1-year-old branches. There are various formulas for computing this. (The variety 'Concord' may serve as an example. You are sawing off all branches that have borne fruit, remember. Weigh them. For the first pound of sawed-off branches, allow yourself to leave 30 buds (that is, those bumps along vine stems from which new growth will emerge in spring) and for each additional pound of prunings, allow 10 further buds.
(If your prunings of old wood amount to five pounds, then you add 30 plus 10 plus 10 plus 10 plus 10, and get a total of 70 buds. Now turn your attention to the 1-year-old wood that grew but did not fruit last summer, and decide which 70 buds you will keep.
(If you are retaining four branches of 1-year-old wood, you could keep 17 buds on each branch.)
There is nothing alarming about this, once you really get it through your head that wood that has already borne is not going to bear again.
To put it another way, a leaf bud emerges in May and grows into a branch several feet long during the summer, bearing no fruit. The next year it bears grapes all along its length, but the year after that it bear none.
The whole rhythm, then, is to produce new branches one year, to bear fruit the following year and to be pruned off the winter following the harvest.
This process goes on forever. Longer than the gardener does, alas.
But suppose you are growing grapes over an arbor, rather than trained on wires.
Have no fear.The grape vine does not care whether it is growing over other plants or along fences or against walls or over roofs. It does not even care how much new wood and old wood there is.
But you do. You want grapes. That is why you keep a balance, by pruning, between new wood and old, pruing away the old when it has finished bearing.
Whether you grow the grape on a wall or a fence or an arbor, you still keep the balance, if you want fruit. On an arbor, you climb up there and prune out the wood that has borne fruit, just as you would prune it out if it were growing on a wire trellis.
The more wood that is pruned away, the more fruit-buds you can leave on the 1-year-old wood, to bear fruit next summer.
You do not have to weigh the prunings, but sometimes it comforts nervous amateurs to have guidelines about how much 1-year-old wood to leave. I suppose it is apparent that when you prune out a 10-foot branch, you cut it up in pieces a foot long before you put it in a sack and set on the scales to weigh it.
Suppose you ask, "How do I know which is old wood from years past and which is new wood that only grew last summer?"
Look at the vine. You will see. The wood of the past summer which has not yet borne fruit will be supple and fresh looking. The old wood will be shaggy and tough.
I think it safe to say that any gardener who can differentiate, merely by looking, between an 18-year-old girl and an 85-year-old elder statesman will have no difficulty telling old branches from new on his grape vine.
Pruning is done with any sharp shears. Even hedge clippers, if it comes to that. For pruning very old neglected vines with branches an inch and a half thick, of course you use a saw, not your good pruning shears.
There will be mild delightful days during the winter. Those are the days to go out and prune the grapes, not at the height of a blizzard. Or at least it is on such days that I prune my grape vines, but if a gardener has a taste for ice storms I suppose any day would do.
February is a good month, but then any time after Christmas seems to work well. One final thing, you may be horrified how much is pruned away and how little seems to be left. Sorry. That's life. The vine is not mocked. Don't try to keep more than should be kept.