What makes a great vintage?
Grape-growing is essentially an agricultural activity. When you think about trying to grow healthy plants in your garden, it’d be fair to say you think about adequate sunlight, water, soil nutrition, and protection from severe weather. Viticulturalists, vineyard managers and winemakers also think of all these things, on a large scale. When growing on the scale of a vineyard, it is inevitable that within a large site, the soil conditions and micro-climates will be slightly different.
So before talking about the right conditions for a great vintage, we need to be clear about the terroir of the particular vineyard. For example, some vineyards are on a slope, and so will drain water better than a flat site. Some vineyards are in valleys where they are shielded from some extreme weather patterns. Others are close to bodies of water, which naturally fight off frost but may suffer exposure to wind or other strong conditions. It’s important to realise that each vineyard site has different factors that make ‘a perfect vintage.’ A combination of weather factors and vineyard management come together to make a great vintage. Here are just a few of the steps along the way – they are by no means all the factors you need for a great vintage.
Winter – Adequate winter rains
For most grape growing regions, particularly in Australia, winter rain is helpful to create good soil moisture and water reserves. This means that, as the vines are dormant in winter, when spring arrives and the vine’s growth cycle begins, it has lots of water to draw on to nourish its growth. As I said above, each vineyard site is different, and each will need differing amounts of rain. There’s no one amount of ‘good rain’. Flatter sites might require less than sloping sites, but soils with poor drainage might require less than those with great drainage.
Early Spring – Budburst
After winter pruning, and when the weather starts to get sufficiently hot warm in late winter and early spring, the previously pruned canes on the vine will begin to sprout buds that will eventually give way to the grape bunch. Warm but not hot weather in this period will result in healthy buds. Frosty or unseasonably cold weather can inhibit the growth of buds, which may damage future development of grape bunches. At this stage, constant warm weather with average rain will keep disease away but also promote healthy buds. The soils of the vineyard are again important here, because freer draining soils with stones will warm faster in winter, and so promote budburst earlier. This helps in cooler climates because the eventual bunches will then have a longer time to ripen. Soil with more clay will be cooler and wetter for longer, and so the growing season beginning with budburst will be a little shorter (unless there’s warmer weather!).
Late Spring/Early Summer - Flowering and fruit set
Flowering occurs the buds have accumulated enough nutrients, and are fed by enough warm weather and sun, to break into bunch components. Air temperature is probably the most important part of this, because cooler weather will delay flowering by anywhere from days to weeks. This, again, has implications for the long-term development of the grape bunches. They later they develop, the less time they have to ripen and develop the sugars and the structures. The soil warmth is really only important here for the grape variety. Some grapes flower earlier than others, so, for example, if your vineyard grows mostly Chardonnay, you will want the weather in the early flowering period to be the best. Most red grape varieties are mid-season flowerers, and so need warmer weather slightly into Summer, depending on where your grapes grow. Provided air temperatures are moderate, there’s no water stress, and low moisture in the air, fruit will set well.
Summer – Veraison
The crucial point where the small grapes grow and take on their eventual colour. This is all due to the chemical reactions in the grapes, which are accumulating the sugars and compounds of their final form. Canopy management is most important here, so that there’s not too much leaf covering on the vines to prevent healthy growth.
Summer/Autumn – Ripening and Harvest
The most crucial things during the full ripening and pre-harvest stage are weather extremes (extreme frost, extreme heat, bushfires that cause smoke damage, or hail) that may damage the healthy bunch. Wasp activity is also something to be careful of, as they will suck the great juice from the grapes and make them shrivel. Lots and lots of rain pre-harvest might also have the potential to fill the grapes with water, thereby diluting the flavourful and structured juice inside. To come back to our beginning, each vineyard has its own ripening and growth characteristics. It’s important to read the winemaker’s notes to know just how their vintage was.
FIVE CHARACTERISTICS OF A GREAT VINTAGE
MILD GROWING CONDITIONS – NO PROLONGED EXTREME AIR TEMPERATURES.
AVERAGE RAIN – NO LONG RAINFALLS, NO ICE OR FROST (UNLESS WANTED!) AND DEFINITELY NO HAIL!
THE RIGHT WEATHER FOR THE VINEYARD – NOT ALL VINEYARDS WANT THE SAME WEATHER.
TRUST THE VINEYARD MANAGER – THE CLASSIC SAYING IS THAT THE BEST WINE IS MADE IN THE VINEYARD, AND THAT YOU CAN MAKE BAD WINE FROM GOOD GRAPES, BUT NOT GOOD WINE FROM BAD GRAPES.
NORMAL WEATHER DOESN’T MEAN GREAT VINTAGE. SOME OF THE BEST VINTAGES IN HISTORY ARE THE RESULT OF HOT YEARS OR OF COINCIDENTAL AND LUCKY WEATHER CHANGES.