Recently during a quick trip to the UK to attend Vineyard Magazine’s excellent trade fair in Kent, I got to catch up with many vine growers. There soon became a common theme to recount in our conversations; the recent harvest time and how common were juggles around crop loadings.

This is a complex subject, especially since people who are considering undertaking some removal of what they feel are excessive grapes, are never in a position to know what the weather will be like in the many weeks ahead.

However there are some fairly simple generalisations that are probably of good benefit to be aware of.

Naturally extensive experience eventually shows itself to be the best teacher around matters of fruit thinning.

Another being to hold effective talks with the winemaker to seek out a compromise in how much work to undertake, and to attempt to deliver a balanced crop of quantity and quality of grapes, (focused towards an agreed style of wine.)

The matter of quality needs to be understood and agreed between all parties if the best results are to be achieved, in much the same way as discussing issues like fungal infection on the grapes.

One of the main problems to be found in the cool margins of a climate for crop growing, is that too much crop simply has not enough time to accumulate adequate sugars, and to metabolise away the acids.

If you do not start thinning your crop soon enough, then you’ll never get on top of any arising problems.

Quite a good, and simple, exercise is to make a graph showing the effective ‘growing degree days’ available to you, in the final couple of months of the season.

In simple terms plants are not able to function under 10°C, or in the dark!

Have a look at the number of hours of effective plant activity, say, 10 days prior to the equinox, (September 21,) and compare that to the number of hours 10 days after the equinox – the equinox is the time of the fastest change of daylight hours, and once those hours, and temperatures, have fallen below a effective functioning amount there is very little that can rescue your increasingly challenged crop at this time.

As readers of my previous thoughts are aware, I do not favour relying on chemical intervention in the winery.

It being preferable to seek more appropriate varieties, and then consider forms of management that assists a better outcome.

Simple matters to consider might include some of the following.

There are some varieties, or even perhaps a ‘family’ of varieties, that are inclined to grow secondary shoots and on which grow a second crop of grapes. This can be found in some of the French selections of clonal material of the Pinot group, as a point of illustration.

If you can, it is best to remove this second set, and earlier rather than later. They are a liability.

With some stronger growing situations or varieties, there can be what are called ‘double budding’ shoots along a cane.

The second shoot being shorter and weaker. This will never come to much and only serves to hold back the rest of the vines, so take them off, and again early.

In a similar manner a vine that is a bit short in ‘over wintering reserves’ of energy, can have a restricted amount of growth in some of the buds that lie in the centre of the cane. If it becomes obvious that the new shoots are slowing down in their growth, then simply ‘nip off’ the top flower, (or young bunch.)

Likewise some people find that the two shoots arising out of the buds at the far end of a cane, might give rise to possibly three flowers.

This being the case then take off the top one. (Another variation of this is to let them grow, and come a time when the acids are falling a little, and the sugars are rising – probably some time after veraison – then the top two bunches can be harvested from which to make grape juice out of.)

All of the above activities can be undertaken around flowering time, or shortly thereafter.

I have heard people comment that they in some form, fear the vine compensating for the loss in potential berries by multiplying the amount of cell growth in the remaining berries. Thus come veraison the berries swell up larger and the vine has less skin area in its berries relative to the volume of pulp…but I have never seen studies on this and generally feel that if over all there is a smaller, and thus better developed crop, then over all this is the best outcome to seek.

It is worth noting that vines are not entirely effective in creating photosynthates in one shoot, ‘translocating’ those compounds down the shoot…along the cane….and then up another shoot, (with which to ripen a bunch of grapes on a differing cane from which the sugars were formed,) Yes these complex compounds are created to be reserves within the vine, and might get to power root growth, build up reserves in the trunk, or even lignify/mature a shoot to become a cane, but in general as soil solution goes ‘up,’ the results come ‘down’.

If you have a lot of short shoots in the centre of the cane on the wire, then you must adjust your thoughts around pruning, for the coming season. (As indicated previously.)

Overall it is the balance within the vine that you should give consideration to, perhaps the ratio of leaf area to quantity of grapes to be ripened.

With experience, and with some varieties, there might well be other aspects of early crop thinning that might well hold advantages.

For example, supposing you are growing a variety that has quite pronounced ‘wings’, or ‘shoulders’ to the bunches, then these can be nipped off. The rationale to this being that the ‘wing’ is usually a little later in forming/developing, and while these might hold back the complete cluster, it still retains the highest acid levels.

I also know of people who have vines with clearly noticeable unusually long, cylindrical clusters. At a time that suits them, but probably not long after fruit set, they go through with long bladed clippers and cut the flower in half; simple, quick, and for their needs, effective.

A little later on it can be noticed in some varieties, especially well coloured examples, that perhaps there are considerable merits for completely taking off any remaining green clusters, at a time when, for example, 90% are further developed.

The point of the exercise here being to tighten up the range of ripe to unripe clusters.

Good wines, in any climate, are not those that have broad range of ripe to unripe characteristics. It being absurdly naive to suggest that to harvest grapes like this results in ‘interesting complexity’.

All this besides, once again I will say that when hand harvesting, there are considerable merits in taking quite a lot of time in getting the harvesters to understand just what it is that you are looking for. (Maybe not enough wineries operate a sorting table?)

For example, in varieties that grow quite a bit of second set bunches, (which for one reason or another did not get removed previously,) collect a few of these bunches and then get people to eat them. They will learn very quickly…” If you do not want to eat the grapes, then I do not want them in my wine.”

But it should not come to this, as much of the most effective fruit thinning can be attended to surprisingly early in the growing season. I have done a lot of panic fruit thinning, and running just ahead of a mechanical harvester, but I have also come across well managed blocks of vines that had effective fruit thinning at a time that suits the vineyard manager.

Part of what I write about ‘effective fruit thinning’ is the recognition that nobody ever wants a lot of second rate grapes, or to have to deal with the resulting chaos. (As has been said for centuries ‘you cannot make a silk purse out of a sows ear’…)

Additional things to consider are: extra work in the winery, tank space etc, doubling up on chaptilisation and other expenses, ‘Dumping’ the resulting wine into the wine lake of the ‘bulk market’… or deciding to buy unbudgeted bottles, labels, cartons etc and to then have to double up sales efforts into a very congested market ?

I do know of people who annually quite early in the growing season, go through their vines and moderate the vines crop loading.

One such person told me that he expects to drop 50% of his potential crop.

Whilst he knows that in a good year he loses some potential income, he is also wise enough to know that every year he will get the best crop available to him, he knows what will happen in the winery, (no nasty surprises,) and easy sales are assured.

Far be it for me to suggest that he is getting it all wrong. So it is all up to you, your choice.

Oh, and good luck, as I know (having grown Pinot Noir and Chardonnay for 10 years,) just how fickle the weather can be.