Huglin index facts for kids
The Huglin heat sum index helps vineyard owners figure out if a certain type of grape variety will grow well in their area. It's like a special way to measure how much heat a place gets during the growing season. This index was created by Pierre Huglin.
Every type of grape needs a specific amount of heat to grow properly and produce good fruit. The Huglin index helps farmers choose the right grapes for their land. It looks at temperatures from the start of April to the end of September.
How the Huglin Index is Calculated
The Huglin index measures the total heat a vineyard receives. It uses both the average daily temperature and the highest temperature each day.
Here's how it generally works:
- It takes the average of the daily mean temperature and the daily maximum temperature.
- Then, it subtracts a base temperature of 10 °C (50 °F). This is because grapes only really start growing when it's warmer than 10 °C.
- These daily numbers are added up for every day from April 1st to September 30th.
- Finally, the total sum is adjusted slightly based on how far north or south the vineyard is (its latitude). This adjustment helps account for different daylight hours in different places.
Sometimes, the heat sums calculated from weather stations can be a bit lower than the actual heat in the vineyards. This is because special spots, like sunny hillsides, can be warmer than the general area.
Huglin Index for Different Grape Varieties
Different grape varieties need different amounts of heat to grow best. This table shows the typical Huglin index range for various popular grape types:
| Huglin-Index H | Grape Variety |
|---|---|
| H < 1500 | |
| 1500 ≤ H < 1600 | Müller-Thurgau, Blauer Portugieser |
| 1600 ≤ H < 1700 | Pinot blanc, Grauer Burgunder, Aligoté, Gamay noir, Gewürztraminer |
| 1700 ≤ H < 1800 | Riesling, Chardonnay, Silvaner, Sauvignon blanc, Pinot noir, Grüner Veltliner |
| 1800 ≤ H < 1900 | Cabernet Franc |
| 1900 ≤ H < 2000 | Chenin blanc, Cabernet Sauvignon, Merlot, Sémillon, Welschriesling |
| 2000 ≤ H < 2100 | Ugni blanc |
| 2100 ≤ H < 2200 | Grenache, Syrah, Cinsaut |
| 2200 ≤ H < 2300 | Carignan |
| 2300 ≤ H < 2400 | Aramon |
How Climate Change Affects Grape Growing
Because of climate change, the world is getting warmer. This means the Huglin index values are also rising in many places. As temperatures increase, the best places to grow certain grape varieties are changing.
In northern parts of Europe, for example, farmers are now able to grow grape types that used to only thrive in warmer, southern regions. This is a big change for the wine industry.
For instance, grapes like Cabernet Franc, Cabernet Sauvignon, Merlot, and Syrah are now successfully grown in warmer areas of Austria. These grapes were once thought to be only suitable for much hotter climates.
