We just got a new grapevine and planted it in the perfect spot in the garden. The only problem is that its leaves started to droop and wilt. The small bits of information online weren’t too helpful, so I did more research. Here’s what I found about grapevine leaves drooping and wilting.
Grapevines leaves droop from improper watering, heat stress, transplant shock, and diseases such as Verticillium wilt. To prevent droopy leaves, only water when the soil is dry, avoid transplant shock, and protect against temperatures above 80ºF if possible. Apply compost and mulch to further reduce drought stress.
So, while grapevine leaves droop and wilt for several reasons, how can we tell which issue is causing it, and how can we fix it? Let’s take a closer look.
Under-Watering
When grapevines are under-watered, their leaves are one of the first things to dry. This commonly appears as drooping, curling, browning, and dropping (generally in that order).
If grapevines aren’t watered soon after, they can lose all of their leaves. And if it gets to the point where all of its leaves dropped and the plant used up most of its energy reserve, it won’t have enough to produce new leaves and will begin to die.
Fortunately, there’s an easy way to address under-watered grapevines.
The best way to water grapevines is by only watering when the first 2-4 inches of soil is dry. You can check this by pushing a finger into the soil, under the plant’s canopy. The goal is to have soil moisture similar to a wrung-out sponge.
When watering, make sure to soak the soil down to 2 feet deep as over 90% of the grapevine’s roots are found at this depth.
Additionally, providing compost and mulch goes a long way to preventing under-watering.
Compost not only provides valuable nutrients for grapevines and their beneficial soil life, but it greatly improves the soil’s water retention. For example, every 1% increase in the soil’s richness or organic matter leads to an additional 20,000 gallons of water held per acre (source).
Mulch reduces evaporation, regulates soil temperature, and prevents soil erosion. You can even use living mulches such as cover crops.
Every year a cover crop is planted in our best vineyards in Napa. A cover crop is comprised of many different plants that are strong in different micro-nutrients that grapevines might need and that the soil might be deprived of after the previous growing season.
Grgich Hills Estate
Apply 2 inches of compost and 4 inches of mulch under the grapevine’s canopy. Reapply compost every 1-2 months and mulch every 3-6 months. When applying, keep both materials at least 3 inches away from the grapevine’s main stem to prevent mold buildup.
However, if your grapevine’s soil isn’t drying and is staying sopping wet for long periods, it’s likely over-watered.
Over-Watering
You can tell if your grapevine is over-watered when its soil is staying sopping wet for more than 1 day after watering. If the soil is starting to smell like a swamp, diseases such as root rot and Verticillium wilt could be taking hold.
Other symptoms of over-watered grapevines are leaves drooping, wilting, and yellowing, as well as dying roots.
As with under-watering, the solution to over-watering is to only water when the first 2-4 inches of soil is dry. That’s all!
However, there are times when the soil has poor drainage and needs to be addressed before proper watering can take place.
Poor Drainage
| Soil Type | Pros | Cons |
|---|---|---|
| Sand | Good drainage | Doesn’t hold nutrients well |
| Silt | Holds nutrients well | Poor drainage |
| Clay | Holds the most nutrients | Even worse drainage than silt |
Planted Grapevines
If your grapevine is already planted and mature, avoid digging into the soil to amend as this disturbs the plant’s established roots.
Poor drainage is common with clay soils while fast drainage is common with sandy soils.
This has to do with the particle size and how it compacts (see the graphic below for a size comparison of sand, silt, and clay).
You can test your soil’s drainage by doing a percolation test.
Simply dig a 1-foot by 1-foot hole nearby and fill it with water. The sweet spot is to have soil drainage of 2 inches per hour (or as close to it as you can get).
Funny enough, the solution for both poor and fast drainage is the same—more organic matter (AKA compost).
Organic matter improves poorly draining soils by working larger particles into the soil, breaking up the compact clumps of ground. On the other hand, fast-draining soils benefit from the water-retaining properties of organic matter.
Apply 2 inches of compost every 1-2 months. Over time, the organic matter works its way into the soil, improving the drainage.
Pro-Tip: Avoid providing your grapevines with mulch until their soil is no longer poorly draining or waterlogged.
For grapevines that haven’t been planted yet, consider planting them in raised beds or on mounds of soil to have gravity assist with drainage.
Potted Grapevines
Potted grapevines are easier to amend as their roots are naturally confined by the pot or container. This means there’s much less of a chance of transplant shock.
So, if your potted grapevine has collapsed or waterlogged soil, repot it with fresh potting soil.
This actually happened with my potted Kaffir lime tree. After it got root rot (and smelled like a swamp), I repotted it with new and dry potting soil and it made a quick recovery!
Heat Stress
Grapevines do best in USDA hardiness zones 4-10. However, some varieties such as Valiant can be grown down to zone 2.
Frost isn’t much of an issue for grapevines as they can withstand temperatures down to -20ºF, but the same isn’t true for heat.
While many grape varieties can grow up to zone 10, they do best when the temperature is under 90ºF. Any hotter, and they won’t be able to cool themselves effectively, causing their leaves to droop, wilt, curl, brown, and drop.
Pro-tip: For best growth and fruiting, keep grapevines within -20ºF and 80ºF if possible.
Grapevines cool themselves in two primary ways: root moisture and transpiration.
Root moisture is fairly common sense, as the plant’s roots transport moisture from the ground to the rest of the plant to keep it cool (including the leaves), but what’s transpiration?
Much like humans, plants breathe and release moisture when hot. For plants, this is called transpiration. But when the climate is too hot and dry, transpiration and root moisture can’t effectively keep up to cool the plant and its leaves. As a result, the grapevine’s leaves droop or curl, and then dry, brown, and drop.
Of course, there will be times when the temperatures exceed 80-90ºF. So, aside from watering, what can we do to help keep our grapevine cool?
Tips for Hot Weather
- Apply 2 inches of compost and 4 inches of mulch. I already mentioned this, but these are the two key practices to avoiding under-watering and heat stress!
- Provide partial shade, especially from the hot, afternoon sun.
Grapevines evolved as vines in forests, so they prefer wrapping around large trunks such as oaks. Contrary to popular belief, the oak tree won’t get strangled by the grapevine.
What’s cool is that both plants benefit from this relationship!
The oak gets extra nutrients from the grapevine’s roots, leaves, and fruit (plus the wildlife it attracts), and the grapevine gets a living trellis and shade from the oak.
Keep in mind that oak trees aren’t the only companion plants for grapes. Many vineyards are also finding great results by adding cover crops below the grapevines.
Transplant Shock
If your grapevine was recently planted or repotted, and its leaves are wilting or drooping, it’s likely due to transplant shock. Transplant shock occurs when a plant is exposed to a new environment and has to establish a new root system.
Avoid transplanting grapevines unless necessary as it can take up to 1 year for recovery.
To help avoid transplant shock, I like to plant with the following steps in mind:
- Have the new ground (or pot) prepared
- Remove as much of the plant’s current topsoil as possible, without damaging the shallow roots
- Grab the base of the plant’s stem and wiggle lightly
- Using your other hand, scoop up and support the rootball
- Lightly place the plant in the new ground (or pot) and fill it in
- Make sure the soil is at the same level on the plant as before
- Apply 2 inches of compost and 4-12 inches of mulch to the top of the soil
- Water generously and add more soil as needed
Diseases
Root Rot
Root rot, or Phytophthora root and crown rot, are fungus-like water molds that affect most, if not all fruiting plants. Causes of root rot are typically over-watering or soils with poor drainage. Symptoms include stunting and leaves wilting, drooping, discoloring, and dropping.
You can typically tell if your grapevine has root rot if the soil is staying sopping wet and starts smelling. As mentioned earlier, allowing the soil to dry out or repotting grapevines with new potting soil are the best ways to amend this disease (source).
Verticillium Wilt
Verticillium wilt is a fungus that is similar to root rot in that it usually occurs in soils with excess water. Additionally, over-fertilizing can also cause it.
The most susceptible fruit crops that contract verticillium wilt are nightshade (tomatoes, peppers, and eggplants), but other fruiting plants such as grapevines can also be infected. Symptoms of this disease include leaves wilting, yellowing, and dropping, with potentially branch dieback.
You can prevent and treat verticillium wilt by pruning infected branches, avoiding excess water and fertilizers, and following best gardening practices (source).
