The vine, an age-old plant at the heart of our viticultural heritage, follows a complex life cycle that fascinates professionals and amateurs alike. This annual vegetative cycle, punctuated by the seasons, determines the future quality of the grapes and, by extension, that of the wine.
Understanding this cycle is essential for any winegrower wishing to produce quality grapes, but also to anticipate and manage the risks, particularly climatic, that can affect production.
The two great vine cycles
The vine’s development is divided into two distinct periods:
- The vegetative cycle: from March to November, when the plant is actively developing.
- The winter cycle: from November to March, a phase of dormancy or vegetative rest
These two cycles follow one another year after year, allowing the vine to regenerate and produce fruit. Each phase involves crucial stages that require special attention on the part of the winemaker.
Key stages in the vine’s growth cycle
Weeping: the awakening of the vine
At the end of winter, when temperatures begin to rise above 10°C, sap begins to circulate in the vines again. This phenomenon is manifested by the appearance of droplets of sap at the ends of pruned shoots – the vine’s“weeping“. This heralds the start of the vegetative cycle and the end of dormancy.
Budburst: first signs of growth
Between late March and mid-April, the buds begin to swell and open, revealing a sort of cottony down called “budding”. This phase, known as budburst, marks the true beginning of annual growth. The protective scales that covered the buds during the winter fall away to make way for future leaves and bunches.
This is a particularly sensitive period, as young shoots are vulnerable to spring frosts that can destroy the year’s production potential overnight.
Growth and foliage
In spring, young shoots develop rapidly, forming new leaf-bearing branches. These play a fundamental role in the plant’s development, thanks to photosynthesis, which produces the organic compounds needed for growth.
The leaf surface that develops directly conditions the vine’s ability to feed its future grapes.
Flowering and fertilization
Between May and June, around 60 days after budburst, small white flowers appear, grouped together in inflorescences. Each cluster may contain between 100 and 200 flowers. This delicate phase generally lasts around ten days.
Unlike other flowers, which open at the top, grapevine flowers are unique in that they open at the bottom. The quality of the blossom already gives an indication of the year’s yield potential.
Setting: berry formation
Following fertilization, the flowers turn into small, green, hard grapes. This is called fruit set, and marks the beginning of berry formation. If flowering has gone well, the bunches will be homogeneous. If not, we can observe the phenomenon of millerandage, with berries of unequal size.
Veraison: color change and ripening
From July-August, the berries gradually change color:
- From green to translucent yellow for white grape varieties
- From green to red to black for red grape varieties
This phenomenon, known as veraison, marks the beginning of grape ripening. The berries begin to enrich in sugars, while their acidity decreases. It’s the start of a long process that leads to full ripening of the grapes.
Ripening and harvesting
During ripening, the berries swell and accumulate sugars, aromatic compounds and mineral elements, while losing their acidity. This phase is crucial to the future quality of the wine.
Harvesting takes place when the grapes have reached optimum maturity, generally between September and October, depending on the region and grape variety. This is the culmination of the vine’s annual vegetative cycle.
Ageing and the winter cycle
After the harvest, the leaves change color and fall off. The shoots become lignified, i.e. they turn into wood – this is known as “lignification”. The vine then enters its winter dormancy phase, during which its growth is halted.
This vegetative rest is necessary for the vine to replenish its reserves and prepare for the next cycle. During this period, the winegrower proceeds with pruning, an essential operation that largely determines the future harvest.
The climatic challenges facing vines
Throughout its life cycle, the vine faces various climatic challenges that can have a serious impact on its development and production:
Spring frost: a major threat
Spring frost is one of the most serious threats to winegrowers. It occurs after budburst, when the young shoots are particularly vulnerable. A single night of frost can destroy a large part of the harvest potential.
There are two types of frost:
| Gel type | Characteristics | Impact on vines | Conditions |
|---|---|---|---|
| Radiative frost | Cooling of the ground by thermal radiation at night | Formation of a layer of cold air at ground level | Clear skies, calm night with no wind |
| Advective frost | Arrival of a cold air mass with wind | General cooling, no temperature inversion | Passage of cold fronts, polar invasion |
Radiation frost is most common in spring. The temperature at ground level can be up to 5°C lower than at a height of 10 meters. This phenomenon is particularly dangerous, as buds and young shoots are located precisely in this zone of cold air.
Other climate challenges
In addition to frost, vines can also be affected by..:
- Hail, which can destroy leaves and bunches of grapes
- Periods of intense drought
- Excessive rainfall favors cryptogamic diseases
- Extreme temperatures (heatwaves, cold snaps)
Faced with these challenges, winegrowers need to implement appropriate protection strategies.
Spring frost protection solutions
There are several ways of protecting vines against frost:
- Candles or heaters placed between the rows
- Fixed anti-freeze towers
- Water spraying (which releases heat as it freezes)
- Straw fires (used less and less often because they pollute)
These traditional methods all have their drawbacks: high cost, pollution, limited effectiveness, complexity of implementation.
This is where a solution like Ventigel comes into its own.
Ventigel: an innovation to protect vines against frost
Ventigel is a mobile frost protection system that combines ventilation and heat supply to effectively protect vines during spring frosts.
Operating principle
The system works in two complementary ways:
- Preventive ventilation: a powerful jet of forced air dries out plots and prevents condensation forming on buds and young shoots. It also redistributes rising warm air during a radiative frost.
- Calorie supply: when temperatures continue to fall, the system provides additional calories thanks to its 110 kW oil-fired heat generator.
Its concentric air jet at over 35 m/s (126 km/h) covers up to 3 hectares and maintains sufficient air movement up to 100 meters from the device.
Advantages of this solution
The main advantages of the Ventigel antifreeze tower over traditional solutions are as follows:
- Mobility: with a width of less than 1 meter, it can be moved and placed between the rows of vines.
- Easy to use: power supply, quick set-up
- Environmentally-friendly: low power consumption (12 kWh) and low fuel consumption (9l/h)
- Efficiency: 60 to 90 metre range depending on terrain configuration
- Flexibility: adaptable to different types of terrain thanks to tilt adjustment
Vineyard work schedule
To optimize vine development and protection, here is a calendar of the main operations to be carried out:
| Period | Cycle phase | Work | Risks | Protection |
|---|---|---|---|---|
| Nov-Feb | Dormancy | Pruning, weeding | Winter frost | Foot mulching |
| March | Crying, budburst | Tying, soil preparation | Spring frost | Setting up Ventigel |
| April-May | Growth, leafing out | Disbudding, trellising | Late frost, diseases | Ventigel vigilance, preventive treatments |
| May-June | Flowering, setting | Raising, trimming | Diseases, coulure | Phytosanitary treatments |
| July-August | Veraison | Leaf thinning, yield control | Drought, storms | Reasoned irrigation |
| Sept-Oct | Maturation, harvest | Harvest, first tillage | Excessive rain | Weather watch |
This calendar obviously needs to be adapted to the specific regions, grape varieties and climatic conditions of the year.
Answers to frequently asked questions about the vine cycle
How long does it take for a vine to produce grapes?
A young vine generally starts producing grapes from its third year of planting. However, production peaks between the 5th and 10th year.
When do vines flower?
Flowering generally occurs between May and June, about 8 to 10 weeks after bud break, when temperatures are sufficiently high.
When do vines start to bud?
Budburst generally occurs between late March and mid-April, when average temperatures regularly exceed 10°C.
When do vines grow?
The vine’s active growth phase extends from March to August, with particularly vigorous growth between April and July.
When does a vine bear grapes?
A vine produces grapes from August (beginning of ripening) to the harvest (September-October, depending on region and grape variety).
Protecting the vine cycle: a crucial challenge
Understanding the vine cycle is essential for winegrowers, who need to adapt their interventions to the different phases of the plant’s development. Among the challenges they face, spring frost remains one of the most formidable, as it can wipe out the potential of an entire harvest in a matter of hours.
Innovative solutions such as Ventigel offer effective, environmentally-friendly protection against this risk. By combining ventilation and heat, this system preserves young vine shoots during frosty nights, ensuring a smooth vegetative cycle and, ultimately, a high-quality harvest.
Against a backdrop of climate change, where late frosts are paradoxically becoming more frequent despite global warming, the availability of such protection tools is becoming a major asset for modern viticulture.
