Wine · Grape Growing · Study guide
The Growing Cycle
A study guide to the vine's year — dormancy, budburst, flowering and fruit set, véraison and ripening, and harvest, the hazards at each stage, and how a vintage is made one turn of the clock at a time.
A wine vintage is one turn of an annual clock. Every year the vine walks the same six stages — sleeping through winter, bursting into bud, growing, flowering, colouring and ripening, and finally giving up its fruit at harvest — and at each stage it is doing a specific job and facing a specific danger. Understand the sequence and you understand why a frost in April or rain in September can make or break a year.
The framing idea: the vine's year is a fixed sequence of stages, each with its own job and its own hazard. The hemisphere flips the calendar (the southern half runs six months offset), but the order never changes. Learn the stages in order — and what threatens each — and the whole climate, water and heat story lands where it belongs in the year. (Part of the Grape Growing library.)
The one thing to fix first: crop rides on last year's timing
The cycle is a relay: what the vine stores in one year powers the start of the next, and the flowers that set the crop were formed in last year's buds. So a vintage isn't made in a moment — it's the sum of every stage. A grower can lose the crop at almost any point (a spring frost, a wet flowering, a rainy harvest), which is why the calendar, not just the climate, decides the wine.
The vine's year, stage by stage
The memorise-cold calendar (northern hemisphere; add ~6 months for the southern):
| Stage | Roughly when (N) | What's happening | The hazard |
|---|---|---|---|
| Winter dormancy | Nov–Feb | Vine rests; lives off stored carbohydrate | Winter freeze (below ~−20°C) |
| Budburst | Mar–Apr | Buds open into shoots as it warms (~10°C) | Spring frost |
| Shoot & leaf growth | Apr–May | Rapid green growth; leaves start photosynthesis | Cold, pests, mildew |
| Flowering & fruit set | May–Jun | Vine self-pollinates; flowers become berries | Coulure, millerandage |
| Véraison & ripening | Jul–Sep | Berries colour, sugar rises, acid falls | Heat stress, drought, disease |
| Harvest | Sep–Oct | Ripe grapes picked | Rain (dilution, rot) |
Key facts
| Hemispheres | Southern harvest runs ~6 months offset (Feb–Apr) |
| Winter job | The vine stores carbohydrate in roots and trunk |
| Budburst trigger | Warmth around 10°C (varies by variety) |
| Fruit set failures | Coulure (poor set) and millerandage (uneven berries) |
| Véraison | The colour change — ripening begins in earnest |
| Ripening | Sugar up, acid down; colour, flavour and tannin develop |
| Harvest wish | Dry weather — rain swells and dilutes, then rots |
The vocabulary you'll actually meet
- Véraison — the moment berries change colour and softening/ripening begins.
- Coulure — widespread failed pollination, so many flowers drop and the crop shrinks.
- Millerandage — uneven fruit set leaving a mix of normal and tiny seedless berries ("hens and chickens").
- Dormancy — the vine's winter sleep, when it isn't photosynthesising.
In this guide
- The six stages in depth — the job and the danger of each
- Winter and summer pruning, and where they fall
- The stage → what can go wrong → effect view
- Classic exam questions
The six stages in depth
- Winter dormancy. After harvest the shoots harden from green to wood (becoming canes), the leaves fall, and the vine stops photosynthesising and switches to a storage phase — banking carbohydrate in its roots and trunk to fuel next spring. The danger is winter freeze: in high-continental regions deep cold can kill buds, and in the extreme the whole vine, with the graft the most vulnerable point (hence "earthing up" over it). This is also when winter pruning happens — late in the dormant season, around February–March — the cut that sets next year's crop (see anatomy of the vine).
- Budburst. As spring warms the soil to roughly 10°C, the buds swell and burst into shoots — earlier for some varieties than others. Early-budding varieties are exposed to spring frost, which can destroy the tender new shoots and buds and slash the crop. Early sprays against fungal disease and pests often begin now.
- Shoot and leaf growth. The shoots grow fast, racing upward until flowering, and the leaves unfurl and begin photosynthesising — the vine's engine coming back online.
- Flowering and fruit set. The vine flowers and, in warm, calm, sunny weather, self-pollinates; each fertilised flower sets into a tiny berry. This is a fragile moment: cold, cloud, wind or rain cause failure — either coulure (widespread failed pollination, so the crop drops) or millerandage (uneven set, leaving a mix of full and tiny seedless berries).
- Véraison and ripening. About six to eight weeks after fruit set comes véraison — the colour change — and true ripening begins: sugar rises, acidity falls, and colour and flavour compounds accumulate in the skins. Tannins (which began forming even before véraison) ripen and polymerise (soften). Warm, sunny weather is ideal, and a little water stress is welcome — it stops the shoots growing and pushes energy into the grapes, while too much water sends the vine back to growing leaves. Growers do summer pruning here — trimming excess leaves and sometimes dropping bunches (green harvest) to open the canopy and concentrate the crop.
- Harvest. The grapes are picked at the chosen ripeness. The one wish is dry weather: sudden rain just before or during harvest is drawn up into the berries, swelling and diluting the juice, and if warmth follows it can trigger rot — turning a promising vintage ordinary in a week.
Stage → what can go wrong → effect
| Stage | What can go wrong | Effect on the vintage |
|---|---|---|
| Dormancy | Severe winter freeze | Dead buds or vines; lost/short crop |
| Budburst | Spring frost | Destroyed shoots; smaller crop |
| Flowering | Cold/wet weather | Coulure/millerandage — reduced, uneven crop |
| Ripening | Heat spike or drought | Stalled ripening; unbalanced fruit |
| Harvest | Rain | Dilution and rot |
Classic exam questions
- Name the six stages of the vine's year in order. — Winter dormancy → budburst → shoot/leaf growth → flowering & fruit set → véraison & ripening → harvest.
- What does the vine do in winter? — Goes dormant, stops photosynthesising, and lives on carbohydrate stored in roots and trunk.
- What triggers budburst, and its danger? — Warmth around 10°C; the danger is spring frost on the new shoots.
- Coulure vs millerandage? — Coulure = widespread failed set (crop drops); millerandage = uneven set (mix of normal and tiny seedless berries).
- What is véraison and what happens after it? — The colour change; then sugar rises, acid falls, and colour/flavour/tannin develop.
- Why is a little water stress good at véraison? — It stops shoot growth and pushes energy into ripening the fruit.
- Why is harvest-time rain a problem? — It dilutes the berries and can bring rot.
Six stages, one clock — the vine does the same walk every year, and the vintage in the bottle is simply the record of how each stage went.