Caring for Your Grape Vines and Vineyard During the Summer
Henry Mitchell once said, "The world would be a better place if every human had a grape vine." This timeless sentiment captures the beauty and utility of growing grapevines. Whether you are cultivating table grapes for their luscious fruit or creating a shaded retreat under a grape-covered arbor, summer grapevine care is essential to ensure healthy plants and a bountiful harvest.
With proper summer maintenance, you can manage vigorous growth, enhance fruit quality, and protect your vineyard. Follow these detailed tips to keep your grapevines thriving throughout the season.
The Importance of Summer Canopy Management
The "canopy" refers to the above-ground growth of the grapevine, including its leaves, shoots, and fruit clusters. Proper canopy management is critical for:
- Maximizing Sunlight: Adequate sunlight is necessary for photosynthesis and the development of next year’s fruiting buds.
- Improving Air Circulation: Good airflow reduces the risk of diseases such as powdery mildew and bunch rot.
- Enhancing Fruit Quality: Balanced pruning ensures the grapes receive enough energy while maintaining optimal cluster size.
- Controlling Growth: Vigorous vines can become unwieldy, making maintenance and harvesting more challenging.
Pruning and Shoot Thinning in May and June
Pruning Shoots
- Thin the shoots on your grapevines so they are spaced approximately 3 inches apart.
- Remove excessive leaves, especially if there are more than three layers of leaves blocking sunlight to the lower buds. These buds will produce next year’s crop, so ensuring they receive adequate light is vital.
Removing Suckers
- Suckers are non-fruit-bearing shoots that grow from the trunk or base of the vine. Removing them allows the plant to direct its energy toward fruit production.
Cluster Thinning
Why Thin Clusters?
A mature table grapevine can only support 16 to 20 clusters of fruit. Thinning excess clusters ensures the remaining ones grow larger and healthier.
When to Thin
- Thin clusters before they bloom and again after fruit begins to develop.
- Remove clusters from weak shoots and retain only one cluster per shoot.
Pruning, Hedging, and Leaf Removal in June and July
During the peak of summer, grapevines grow rapidly. Managing this growth is crucial to maintain a healthy balance between foliage and fruit.
Pruning and Hedging
- Aim for shoots that are 3 to 4 feet long with 15 to 22 mature leaves.
- Use garden snips and pruners to trim excess growth, especially shoots leaning over the top of your trellis or arbor. Cut these shoots back to about 6 to 8 inches long.
Leaf Removal for Air Circulation
- Too many leaves can block airflow and create a microclimate ideal for powdery mildew.
- In hot climates, like California, maintain partial shading for fruit clusters.
- Remove leaves on the east or north sides to increase airflow while keeping leaves on the west or south sides to shield fruit from intense afternoon sun.
Arranging Shoots
- Lift and arrange shoots with fruit clusters on your trellis to maximize sunlight and airflow.
- If some shoots do not bear fruit, consider removing them to redirect energy to productive shoots.
Cluster Thinning for Optimal Fruit Size
Even after initial thinning, further adjustments may be needed as the fruit develops.
- Trim the Bottom of Each Cluster: This encourages the cluster to grow round and uniform, improving fruit size.
- Limit Clusters Per Shoot: Ensure each shoot supports no more than one fruit cluster for optimal growth.
Protecting Grapes from Birds
As your grapes ripen, they become a tempting target for birds. Protect your harvest with these tips:
- Bird Netting: Drape bird netting over your grapevines to deter birds from pecking at the fruit.
- Secure the Netting: Ensure the netting is tightly anchored to prevent birds from sneaking underneath.
Preventing Powdery Mildew
Powdery mildew is one of the most common grapevine diseases and can be exacerbated by poor air circulation.
Prevention Tips:
- Maintain proper canopy management to allow air to flow freely through the vines.
- Apply organic fungicides if conditions are particularly humid or if mildew signs appear.
For more detailed guidance on managing powdery mildew, watch our our video and blog post dedicated to this topic.
Fertilizing and Watering Your Grapevines
Summer is a critical time to ensure your grapevines have the nutrients and water they need for fruit production.
Fertilizing:
- Use a balanced fertilizer formulated for fruiting plants.
- Avoid over-fertilizing, as excessive nutrients can lead to overly vigorous foliage growth at the expense of fruit quality.
Watering:
- Provide consistent moisture, especially during dry periods.
- Drip irrigation is an excellent method for delivering water directly to the roots while minimizing evaporation.
Why Summer Maintenance Matters
Regular summer maintenance has a direct impact on the health and productivity of your grapevines. Benefits include:
- Higher Yields: Thinned clusters and healthy shoots contribute to better fruit production.
- Disease Prevention: Proper pruning and airflow reduce the risk of fungal diseases.
- Better Fruit Quality: Well-managed vines produce larger, sweeter, and more flavorful grapes.
- Easier Harvesting: Controlled growth simplifies harvesting and reduces the risk of injury to the plant.
Enjoy the Fruits of Your Labor
Grapevines are more than just a source of delicious fruit—they are a connection to ancient agricultural traditions and a beautiful addition to any garden. By dedicating a little time to summer care, you’ll ensure your vines remain healthy and productive for years to come.
Whether you’re growing table grapes in your backyard or tending to a small vineyard, these practices will help you achieve a bountiful harvest. For more guidance, watch Chuck Ingels, Sacramento County Farm Advisor, in his video on summer and winter grape pruning.
12 comments
Gerry, they should have leaves in the summer. They drop them over the winter so most likely your grape is dead. You can do a scratch test to find out. Just scrape off a little of the bark and you should see green if the plant is still alive, brown if dead.
I live in the in Arizona and planted one grape plant and it looks dead… Do they hibernate Or is my plant A goner?
Kay, pruning the leaves away allows better air flow and also allows more sun to penetrate into the area where the grapes are. You do need some leaves on the cane that your grapes are growing on, so you don’t want to prune right up the the cluster. It needs some leaves to produce “food” for the growing cluster.
Somebody told me pruning back the leaves away from the grapes makes them grow better and bigger because the energy the plant would put into the leaves in now going into the grapes. That didn’t make sense to me. But is it true? Can you explain?
I planted a Thompson seedless in February and it is my first grape vine. I want to train it onto a double wire trellis but am wondering if I should heavily prune it now to strengthen the trunk or let it grow and wait until winter?