When you bite the fleshy, juicy pulp of grapes, it’s easy to assume that they need a lot of water. However, grape vines are very efficient users of water. Not only should you know how much water they need, but how often to water them if you want healthy fruits.
You should water a grapevine with an inch (2.54 cm) of water once a week. Young grapes need more water, so saturate the soil in a 3 x 3-foot (91×91 cm) area weekly. Older vines rarely need watering because of their deep roots. However, if the soil is well-draining, drench the root zone weekly.
The amount of water needed and how often you should water grapes depends on the age of the vine, the grape variety, soil conditions, and the season. I’ll discuss these factors as well as the risks of underwatering and overwatering grape vines.
How To Water Grape Vines
Grape vines are hardy and drought resistant. However, they still need water to thrive. Underwatering can cause the leaves and fruits to fall prematurely whereas overwatering will result in root rot and grape diseases. Therefore, you’ll need to find a balance when watering grape vines.
Here are some helpful suggestions:
- Water young grape vines (first two years) with an inch (2.54 cm) of water weekly.
- Saturate the root zone. Use at least 5 gallons (18.9 liters) of water in a 3 x 3 foot (91.4 cm x 91.4 cm) area. This will give you about an inch of water for the week.
- If you live in arid areas like Central California, you may need to use more water, approximately 8 – 10 gallons (30.3 – 37.9 liters) per week.
- Newly transplanted grape vines require immediate and regular watering to ensure they don’t die from transplant shock. This is especially important for grape vines growing in pots.
- Drench the soil for newly planted grape vines 6 – 10 inches (15.24cm – 25.4cm) into the soil. If you water your grapes any deeper, the roots may start to rot.
- Once the trunk is established, the grapevine no longer needs as much water as it did in the first few years. However, you should maintain the same watering patterns if your grapevine is growing in sandy soil or if there is a prolonged drought.
- Avoid watering the leaves because it will encourage grape diseases, like downy mildew and powdery mildew.
- Water grape vines less frequently in the fall as the vines need to harden in preparation for winter.
- Older vines can go for extended periods without water unless the soil is well-draining. However, if your region goes too long without water, you should drench the root zones with water up to 12 inches (30.48cm) deep.
- When the vines start to fruit, you slow the watering. Instead of watering weekly, you can do it bi-weekly. This will encourage fruits to ripen.
Watering Grape Vines According to Growth Stage
Like other plants, grape vines have different watering needs, depending on the stage of growth. Younger plants need water more because they have a shallow root system while older, more established grape vines have more access to water due to their deeper root system.
Below are stages of growth that can guide you on how to water your grape vines.
| Growth Stage | Watering Pattern |
| Bud break to bloom | Very little water |
| Bloom to fruit set | Regular water (an inch/2.54cm) a week |
| Fruit set to when they start to ripen (veraison) (Young roots start dying and are replaced by new growth, so the vine needs more water for both the roots and fruits) | Deeper or more water |
| Growing season (rapid growth of canopy and leaf area) | More water |
Best Ways To Water Grape Vines
Knowing how much water and how often to water your grape vines is not enough. You also need to know how best to water the vines. You should opt for methods that will get water to the root zones without getting the foliage wet.
Let’s explore your options.
Drip Irrigation
Drip irrigation is one of the best ways to water your grape vines. The water gets right into the soil and feeds the roots without getting the foliage wet. However, there is the risk of overwatering or underwatering the grapes if you don’t keep track of the amount of water you are giving the vines. To avoid this scenario:
- Start by testing the drip lines on a bare patch.
- Allow the water to run through the drip lines for five minutes.
- Turn off the water and wait for some time for the soil to take in the water.
- Check the soil to identify the depth of wet soil. For example, if 5 minutes of drip irrigation gives you 2 inches (5.08 cm) of water, then you can easily tell that 10 minutes of watering will give you 4 inches (10.16 cm). When watering established vines, you need to run the drip lines for at least 3 minutes to get 12 inches (30.48 cm) of water.
If you’d like to learn more about drip irrigation, you can check out my other article. I’ll specifically discuss how long you should water your plants and how drip irrigation works: How Long Should You Water a Garden With Drip Irrigation?
Looped Soaker Hose
You can also use the looped soaker hose to water your grape vines. It is similar to drip irrigation, except it’s much harder to regulate the water released. Nevertheless, it’s great for soaking the soil, especially when watering established plants that need deep watering.
The looped soaker hose is ideal for small spaces and gardeners looking to save irrigation costs. However, you’ll need to be keen when using the soaker hose because you can easily overwater the grape vines.
The soil should remain relatively moist during the growing season. Still, it should not be wet because this will encourage fungal root rot.
Signs You’re Overwatering Grape Vines
Unless you monitor the drip lines when watering grape vines, the chances of overwatering are high. Besides keeping track of water depth and watering duration, the grapevine will also tell you if the water is too much.
Signs of overwatering include;
- Yellowing leaves.
- Brown leaf tips.
- Consistently wet soil.
If you notice these signs in your grapes, stop watering them for some time. If you have been watering them once a week, with the recommended water levels, you should wait a few more days before watering.
For example, instead of once every seven days, you can extend it to once every 10 days.
This video offers tips on how to water your grape vines.
Signs of Underwatered Grape Vines
Grave vines grow deep roots. Most grape varieties grow roots 3 feet (0.91 meters) deep. However, some individual roots can grow up to 30 feet (9 meters) deep. These roots sustain the plant during drought, but only for a limited period.
If they do not get enough water, grape vines will start showing signs of underwatering. These include the following:
- The vines stop growing new leaves and tendrils during the growing season.
- Drooping or curling leaves.
- Leaf bleaching.
- Leaves start falling off.
- Delayed fruit ripening.
Even though hardy, grape vines need water for vegetative growth, fruit composition, and winter hardiness. If you notice signs of underwatering, you should increase the watering frequency to once every five days until you see an improvement in your grape vines.
Only increase the amount of water if you have been feeding the vines less than the recommended weekly quantity. The risk of deep watering with additional water is you can easily suffocate the roots.
Table Grapes vs. Wine Grapes
When it comes to watering grapes, you also have to consider the type of grapes. Table grapes usually require water regularly until you start harvesting them. Wine grapes, on the other hand, produce the best flavor when you reduce the water by half in the final stages of ripening.
Start reducing the watering from once a week to once every 10 – 12 days as you get closer to harvesting wine grapes. Most winemakers use this method to increase the concentration of flavors before they harvest the grapes.
Here is a table summarizing the key differences between table and wine grapes:
| Table Grapes | Wine Grapes |
| Thin skin | Thicker skin increases the flavor |
| Larger fruits | Smaller fruits |
| Vines have lots of fruits | Fewer fruits on the vine |
| No seeds or very small seeds | Large seeds add flavor to the fruit |
| Higher yield | Smaller number but higher quality grapes |
| Brix (a measure of sweetness) of 17 – 19 | Brix of 24 – 26 |
Conclusion
How often you water grape vines depends on the type of grapes and their growth stage. Table grapes need regular watering without intentional water stress, as is the case for wine grapes. You should also adjust the watering schedule according to the season and the plant’s needs.
