Grape Growing – The Climate
It seems like I’ve touched a nerve with yesterday’s post about Global Warming. Got some really aggressive replies! Anyway, let’s look at what the ideal climate for growing grapes is – with or without global warming ….he he
The ideal climate for growing grapes can be devided into three components:
The messo climate
The micro climate
The macro climate
In this article I will mostly focus on the macro climate; the one that will determine if your climate is suitable for growing grapes or not.
The messo climate:
The mesoclimate describes the climate within smaller areas such as a region or valley. The climate conditions of a mesoclimate is normally calculated over shorter periods of time (using hourly data) and is influenced by the topographic factors of elevation or altitude, slope inclination and aspect, and proximity to bodies of water. Within a grape-producing region, the mesoclimate of a specific vineyard site has a profound influence on susceptibility to spring freezes and the ripening of your grapes.
The micro climate:
In short, the ideal microclimate is the climate immediately within or surrounding your grape vine canopy and differences occur within a few meters / centimeters and minutes or seconds. It is influenced by the vigor of the grapevine, irrigation, soil management, how you manage the canopy of your grape vine, the row orientation you use, the row spacing etc.
The ideal micro climate influence how successful you will grow grapes, as this will determine the vine’s health and productivity, but will also improve grape quality. Unlike the messo and macro climate, the micro climate is something we have 95% control of and this is where the importance of using the correct viticultural practices comes in (the one’s I teach in the Complete Grape Growing System).
The macro climate:
The macro climate describes the climate of a region, extending over hundreds of kilometers (e.g. the South Western Cape where I live) and is studied over a long time-period (usually 30 years or more), using annual, seasonal or monthly data. The macro climate is influenced by the geographic location (latitude) and proximity to large, climate-moderating bodies of water. The weather may differ from year to year, but the climatic situation over a long period of time is relatively stable in terms of temperature and rainfall patterns.
Various factors, combining various climatic components like minimum temperature, maximum temperature, rainfall, humidity, sunshine duration etc., may be used to describe the viticultural potential of a macro-region. Some use monthly data or daily data only, while others are a combination of different scales (daily with monthly data). They are usually summed for different periods of time (growth season or whole year), but can also use a single month. They are established for a specific country or region, and then may be adapted to other regions or used for a systematic global classification of the climate.
The length of the growing season of grapes differ from variety to variety and studies shows that at least 170 days of active, frost-free, growing is needed for grape vines to ripen a crop (remember, this figure will not be same for all varieties). But not only the length of the growing season is important; the heat accumulated during the growing season will determine if your grape vine will successfully ripen the grapes or not.
You will have to find out how many days of full sunlight with a temperate above 10°C or 50°F is measured where you live. This is called the GDD or “growing degree days”. Studies made on the physiology of the grape vine, determined that the grape vine is not very active below these temperatures.
The GDD is measured by using the following formula:
(HT + LT) / 2 – 50°F or -10°C=GDD *
HT = highest temp; LT= lowest temp
By adding up all the GDD points, you can measure your regions suitability for growing grapes and should be more than 2000 GDD (Fahrenheit) or 1200 GDD (Celsius) points. The closer your macro climate is to these numbers, the more suitable it will be for growing grapes.
As said earlier, the macro and messo climate cannot be changed, but the micro climate is the one you have control of. Use this advantage to grow your own grape vines more succesfully, even if your messo and macro climate isn’t 100% ideal.
For help with creating the perfect micro climate, get the Complete Grape Growing System for only $29!
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