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Bordeaux basics: the rivers, the grapes, the climate and the vineyards
The foundations of Bordeaux for sommelier students: where it is, why the two banks differ, what each grape brings, how the climate shapes every vintage, and how the vines are grown. With a short quiz.
Updated October 2026
Rewritten by Alper Billik, Advanced Sommelier
6 min read
Before the classifications and the famous châteaux, Bordeaux is a story of water, gravel and weather. Understand those three and almost every exam question about Bordeaux has a logical answer. This is lesson one: the foundations.
Where Bordeaux is
- South-west France, around the city of Bordeaux, close to the Atlantic Ocean.
- Two rivers, the Garonne and the Dordogne, meet north of the city to form the Gironde estuary.
- Left Bank: west of the Garonne and the Gironde: the Médoc, the Graves and Sauternes.
- Right Bank: north and east of the Dordogne and the Gironde: Saint-Émilion, Pomerol, Fronsac and the Côtes de Bordeaux.
- Entre-Deux-Mers: the land between the two rivers, known for dry white wine.
The climate: mild, wet and changeable
Bordeaux has a moderate maritime climate. The Atlantic and the Gulf Stream keep winters mild, and the pine forests of the Landes, to the south-west, shelter the vineyards from ocean winds. The estuary and rivers soften extremes nearby.
- The risk is rain, not cold. Rain at flowering causes poor fruit set (coulure and millerandage); rain near harvest brings rot and dilution. See coulure and millerandage explained.
- Spring frost can hit vineyards away from the water.
- So vintages vary, more than in warmer regions. This is why the Bordeaux vintage matters on a wine list.
- And blending is insurance. Merlot ripens early and Cabernet Sauvignon late. If one struggles in a given year, the other can carry the blend.
The soils: why the banks differ
| Soil | Where | Why it matters | Best grape |
|---|---|---|---|
| Gravel | Médoc and Graves (Left Bank) | Drains well and holds the day's heat, helping late grapes ripen | Cabernet Sauvignon |
| Clay | Pomerol, parts of Saint-Émilion and Saint-Estèphe | Cool and holds water, so vines never run dry | Merlot |
| Limestone | The Saint-Émilion plateau and slopes | Fresh, mineral wines with good acidity | Merlot and Cabernet Franc |
| Sand | Parts of the Right Bank and Graves | Lighter, softer wines | Merlot |
- Gravel
- WhereMédoc and Graves (Left Bank)
- Why it mattersDrains well and holds the day's heat, helping late grapes ripen
- Best grapeCabernet Sauvignon
- Clay
- WherePomerol, parts of Saint-Émilion and Saint-Estèphe
- Why it mattersCool and holds water, so vines never run dry
- Best grapeMerlot
- Limestone
- WhereThe Saint-Émilion plateau and slopes
- Why it mattersFresh, mineral wines with good acidity
- Best grapeMerlot and Cabernet Franc
- Sand
- WhereParts of the Right Bank and Graves
- Why it mattersLighter, softer wines
- Best grapeMerlot
This is the logic behind the classic rule: Left Bank blends are led by Cabernet Sauvignon, Right Bank blends by Merlot.
The grapes
| Grape | Ripens | Character | Role |
|---|---|---|---|
| Merlot | Early | Plum, black cherry; soft, round tannins; prone to coulure | About two-thirds of red plantings; leads the Right Bank |
| Cabernet Sauvignon | Late | Blackcurrant, cedar, mint; high tannin and acidity; thick skins | About a fifth of red plantings; backbone of the Left Bank |
| Cabernet Franc | Earlier than Cabernet Sauvignon | Raspberry, violet, a leafy note; medium tannins | Important in Saint-Émilion |
| Petit Verdot | Very late | Deep colour, violet, firm tannin | Small amounts, mostly in the Médoc |
| Malbec | Mid-season | Deep colour, dark fruit | Small amounts in some blends |
| Carménère | Late | Herbal, spicy | Almost vanished after phylloxera; now rare |
| Sauvignon Blanc | Early | High acidity; grapefruit, grass | Dry whites and Sauternes |
| Sémillon | Mid | Body, wax, honey; welcomes noble rot | Leads Sauternes; weight in dry whites |
- Merlot
- RipensEarly
- CharacterPlum, black cherry; soft, round tannins; prone to coulure
- RoleAbout two-thirds of red plantings; leads the Right Bank
- Cabernet Sauvignon
- RipensLate
- CharacterBlackcurrant, cedar, mint; high tannin and acidity; thick skins
- RoleAbout a fifth of red plantings; backbone of the Left Bank
- Cabernet Franc
- RipensEarlier than Cabernet Sauvignon
- CharacterRaspberry, violet, a leafy note; medium tannins
- RoleImportant in Saint-Émilion
- Petit Verdot
- RipensVery late
- CharacterDeep colour, violet, firm tannin
- RoleSmall amounts, mostly in the Médoc
- Malbec
- RipensMid-season
- CharacterDeep colour, dark fruit
- RoleSmall amounts in some blends
- Carménère
- RipensLate
- CharacterHerbal, spicy
- RoleAlmost vanished after phylloxera; now rare
- Sauvignon Blanc
- RipensEarly
- CharacterHigh acidity; grapefruit, grass
- RoleDry whites and Sauternes
- Sémillon
- RipensMid
- CharacterBody, wax, honey; welcomes noble rot
- RoleLeads Sauternes; weight in dry whites
Shares are from the CIVB, the Bordeaux wine council: Merlot 66%, Cabernet Sauvignon 22.5% and Cabernet Franc 9.5% of red vines; Petit Verdot, Malbec and Carménère share the last 2%. A third white grape, Muscadelle, adds floral notes in small amounts. For more on the whites, see white Bordeaux grapes.
In the vineyard
- Pruning: most vines are cane-pruned on the Guyot system, single or double, and trained low along wires so the grapes benefit from heat near the ground.
- Canopy work: leaf removal around the bunches lets air through and fights rot. Some growers now remove fewer leaves to protect grapes from sunburn.
- Green harvest: dropping some bunches in summer to concentrate the rest, common at top estates.
- Disease: in a damp climate the main threats are downy mildew, powdery mildew and grey rot (botrytis bunch rot). Like vineyards everywhere, Bordeaux also fights trunk diseases such as esca and eutypa dieback. More in vine diseases explained.
- Harvest: by hand at most top estates; machine harvesting is common for everyday wine.
Climate change and new grapes
Warmer summers bring earlier harvests and riper, more alcoholic wines. Growers are answering with later pruning, less leaf thinning, earlier and night-time picking, and lower planting density (CIVB). Since 2021 new varieties are allowed in Bordeaux and Bordeaux Supérieur, including the reds Arinarnoa, Castets, Marselan and Touriga Nacional and the whites Alvarinho and Liliorila. They are limited to 5% of a vineyard and 10% of a blend, and can't be named on the label.
The styles, and the pyramid
- Styles: mostly red blends; dry whites; sweet wines from noble rot (Sauternes, Barsac); rosé and the darker Clairet; and sparkling Crémant de Bordeaux.
- The quality pyramid: regional Bordeaux and Bordeaux Supérieur at the base; district appellations such as Médoc, Graves and Côtes de Bordeaux; then the village appellations such as Pauillac, Margaux and Pomerol.
- Then the classifications: 1855, Graves, Saint-Émilion and the Crus Bourgeois. They are lesson two: see my Bordeaux guide for the Certified Sommelier exam.
Then test yourself with the Bordeaux quiz. Still at Level 1? Try the Level 1 practice test. SOMM DIGI AI can quiz you on any region, every day.
Quick check
Question 1
Which two rivers meet to form the Gironde estuary?
- a)The Garonne and the Dordogne
- b)The Loire and the Cher
- c)The Rhône and the Saône
- d)The Lot and the Tarn
Show answerAnswer
a) The Garonne and the Dordogne. The Garonne and the Dordogne join north of the city of Bordeaux.
Question 2
Why does Cabernet Sauvignon do best on the gravel of the Left Bank?
- a)Gravel keeps the vines cool
- b)Gravel drains well and holds heat, helping a late grape ripen
- c)Gravel stops noble rot
- d)Gravel gives higher yields
Show answerAnswer
b) Gravel drains well and holds heat, helping a late grape ripen. Cabernet Sauvignon ripens late; warm, well-drained gravel gives it the extra heat it needs.
Question 3
Which is the most planted grape in Bordeaux?
- a)Cabernet Sauvignon
- b)Cabernet Franc
- c)Merlot
- d)Sémillon
Show answerAnswer
c) Merlot. Merlot: about two-thirds of the red vines, according to the CIVB.
Question 4
Rain at flowering can cause poor fruit set. What is it called?
- a)Coulure
- b)Véraison
- c)Botrytis
- d)Chaptalisation
Show answerAnswer
a) Coulure. Coulure: flowers fail to become berries. Merlot is especially prone to it.
Question 5
The new climate-adaptation grapes may be used in which appellations?
- a)Pauillac and Margaux
- b)Bordeaux and Bordeaux Supérieur
- c)Saint-Émilion Grand Cru
- d)Sauternes and Barsac
Show answerAnswer
b) Bordeaux and Bordeaux Supérieur. Only the regional Bordeaux and Bordeaux Supérieur appellations, within strict limits.
Questions people ask
What is the difference between the Left Bank and the Right Bank?
The Left Bank (Médoc, Graves) has warm gravel soils and blends led by Cabernet Sauvignon. The Right Bank (Saint-Émilion, Pomerol) has clay and limestone and blends led by Merlot.
What climate does Bordeaux have?
Moderate maritime: mild, influenced by the Atlantic, with rain as the main risk. That is why vintages vary.
Why are Bordeaux wines blended?
Each grape ripens at a different time and brings something different. Blending balances the wine and protects the grower in difficult years.
What grapes are allowed in red Bordeaux?
Merlot, Cabernet Sauvignon, Cabernet Franc, Petit Verdot, Malbec and Carménère, plus, in Bordeaux and Bordeaux Supérieur only, a few new climate-adaptation varieties.
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