Viticulture: grape growing

Question 1

What is the annual lifecycle of the grape vine (grape growing)

Answer 1

• bud break - begins in spring (around April 1 in Ca)
• Flowering - around May 15 in CA
• Berry set - berries begin to develop in clusters
• Veraison - onset of ripening (rapis swelling and softening of the berry. Increase in sugar and decrease in acid.
• Harvest - August through October in CA, when sugar reaches 20-25% by weight and acids 0.5-1.0% by weight
• Winter dormancy and vine pruning

Question 2

What are the primary acids in grapes (prior to Veraison)

Answer 2

• Malic Acid - gradually decreases during ripening
• Tartaric Acid - primary acid at harvest

Question 3

What are the primary sugars in grapes?

Answer 3

Glucose
Fructose

Question 4

What is the vineyard heat index?

Answer 4

A cumulative measure of heat in a region that is determined by calculating the Growing Degree Days.

Question 5

How is heat index calculated?

Answer 5

Heat index =
1. calculate the average temperature for each day between April 1 and October 1(growing season)
2. Calculae degree days by subtracting 50 from the average temp (in 1 above)
3. Heat index is the sum of all the degree day values over the growing season.

Question 6

What is the impact of a warmer climate on grape growing?

Answer 6

• Higher sugar levels
• Lower acid levels
• Rapid berry maturation
• Lower color/pigments
• Lower flavor/aroma compounds
• Higher yields

Question 7

What is the impact of a cooler climate on grape growing?

Answer 7

• Lower sugar levels
• Higher acid levels
• Slower berry maturation
• Higher color/pigments
• Higher flavor/aroma compounds
• Lower yields

Question 8

How do you calculate the yield from a ton of grapes?

Answer 8

• one ton of grapes = 160 gallons
• one gallon = 5 (750ml) bottles
• So, 160 gallons = 800 bottles
• 800 bottles/12 per case = 67 cases per ton