Luxembourg’s grape harvest is getting underway earlier than usual this year. Prolonged dry conditions are also revealing marked differences in how vineyards, and even different parts of the same vineyard, are responding.
“The maturity is extremely early,” says LIST agri-environmental researcher Daniel Molitor. “But the vineyards are looking very different.”
In some parcels, vines are developing well and the dry conditions have kept fungal-disease pressure low. In others, particularly younger vineyards and sites with shallow soils, water stress is becoming more visible.
These conditions are particularly relevant for DryVineyard, the research project collaboration between LIST and Luxembourg’s Institut viti-vinicole (IVV) investigating how vineyards can cope with more frequent and prolonged drought.
Funded by Luxembourg’s Ministry of Agriculture, the project runs from 2025 to 2029 and is testing approaches including soil management, drought-tolerant rootstocks, and trees in vineyards, with first results expected towards the end of 2026.
What are researchers seeing?
One observation from this summer is already clear: not all vines experience drought in the same way.
Older vines growing in deeper soils can access water further below the surface. In shallower, rockier soils, roots have fewer options once the upper layers dry out.
Molitor is seeing the consequences in some water-stressed areas, where leaves are yellowing and berries are smaller and less aromatic. Water availability matters for more than yield. It can influence grape development and aroma formation.
Researchers measure soil moisture at different depths and compare how vines respond under different treatments. Molitor says plants under different soil-management strategies are already behaving differently.
It is too early to draw conclusions, but this summer is allowing researchers to test these approaches under the water stress DryVineyard was designed to investigate.
Testing different adaptation strategies
DryVineyard is also testing drought-tolerant rootstocks. Their characteristics can influence how a vine responds to limited water. Some of them may also help delay maturation into later, cooler parts of the season, which is favourable for aroma synthesis.
Trees and photovoltaic structures offer additional possibilities. Trees can provide shade and modify the vineyard microclimate, but they also compete for water and nutrients. As is often the case, the effects of such management adaptations are therefore neither purely positive nor negative, but depend strongly on local conditions and annual weather patterns. For this reason, field trials are generally designed to remain open-ended and are conducted over several years before broader conclusions can be drawn.
Even irrigation is not a straightforward answer. Luxembourg’s vineyards are often located on slopes, away from readily available water. Supplying them can require substantial volumes of water to be transported by tractor and tank.
Preparing for variability, not only drought
The challenge is broader than increasingly hot and dry summers. Environmental and climate research, including LIST’s own research in this area, points to greater variability and more extreme conditions, rather than one uniform shift towards hotter weather.
For vineyards, that can mean prolonged hot and dry periods, but much wetter seasons. Each creates different pressures.
A hot, dry year brings water stress. A wet year can increase fungal-disease pressure and make it more difficult to access vineyards with machinery.
For growers, this variability is one of the biggest adaptation challenges. An adaptation measure that performs well during an exceptionally dry year therefore also needs to be understood under cooler or wetter conditions. This is one reason DryVineyard is gathering evidence across several growing seasons.
Ultimately, adaptation may depend on combining different measures according to the vineyard and the conditions, rather than finding one universal solution.
For Molitor, that does not mean replacing the grape varieties associated with Luxembourg wine.
“For me, it’s not that the traditional cultivars will disappear”, he says. “But we have to adapt our management practices.”
Follow the research
To follow DryVineyard and learn more about the adaptation strategies being tested, visit the DryVineyard project page: https://researchportal.list.lu/projects/detail/dryvineyard.