With so many uses, Grapes are a gret addition to any garden space. Understanding the in’s and outs of growing grapes will help ensure you have a plentiful harvest.
When to Grow Grapes
Grapes do best in slightly warmer temperatures. 61 degrees Fahrenheit, or 16 degrees Celsius provides the optimal temperature, which mimics early Spring. There is a minimum growing season for grapes – at least 150 days with cold temperatures that target the -25 degrees Fahrenheit, or -32 degrees Celsius mark. Optimal sites have full sun exposure, very good soil drainage and n avoidance of soggy and arid conditions.
Types of Grapes and How this Affects Growth
A common method of differentiating grapes splits them into wine grapes and dessert grapes.
Wine grapes are commonly grown outdoors. They require more attention and grow best if they are planted in a warm, sheltered and sunny position. An excellent choice would be a south-facing, or southwest-facing wall or fence.
Dessert grapes grow indoors. They can be ripened within a greenhouse, and also placed in a container to grow in an outdoor conservatory, or even properly outdoors during the winter.
Different varieties will be suited to different climates and soil types. You should choose the variety that suits your particular climate and soil combination.
A way to differentiate grapes that influences how they are grown is in three ways. American grapes and French hybrid cultivars, which grow best in colder regions. This is because they are the hardiest for the winter season. European grapes are the third type, which are best avoided unless you live in a temperate zone. Another way to grow European grapes is to provide winter protection.
Different varieties of grapes have also been classified pertaining to the type of wine they go on to produce:
Red Wine Grapes
New York Muscat AGM: pink to dark-red skin, that produces a blackcurrant flavoured Muscat. These grapes are disease resistant and are best grown in warm conditions. The plant has an overall good autumn colour.
Pinot Noir grapes: need cool climates for a full flavour profile development. These grapes are more vulnerable to botrytis (powdery mildew), so damp conditions should be avoided.
Boskoop Glory AGM: this is great for amateur growers. The crops yield reliably, and the individual plants will be disease-resistant. They grapes are described as moderately good in flavour.
Regent: there is good disease resistance, high yield with a very sweet crop, which overall produces a good quality wine.
White Wine Grapes
Seyval Blanc (or Seyve Villard 5276): has a good level of resistance to both main types of fungal disease faced by grape vines, which as powdery mildew and downy mildew. In addition to this, it produces a reliable crop, and is nice to create blended white and sparkling wines.
Phonix: this is a grower favourite for both wines and juicing.
Muller Thurgau (or Reisling-Sylvaner): this white wine grape has a very high yield with a signature riesling flavour. However, if you are growing in colder temperatures, this grape vine is more susceptible to botrytis, and fruits may not ripen correctly.
Chardonnay grapes: have an early ripening season, producing very aromatic dark golden grapes, that are perfect for sweet desserts, as well as wine.
Other Types of Grapes
Buckland Sweetwater: there is early ripening and high yield. Grapes have very good paste and are suitable to small greenhouse growth. This variety will require extra feeding for optimal growth.
Schiava Grossa (also known as Black Hamburg, and Trollinger): this is a type of grape with very good flavour. The grapes are black and have a very high yield, which makes them perfect for unheated greenhouse growth.
Muscat of Alexandria: produces a very tasty Muscat, which will also require extra heat to grow very well.
Foster Seedling: this variety of grape vine ripens earlier than its counterparts, producing very large bunches of grapes that have an excellent flavour. Due to this, they should be eaten straight after they are picked.
Planting and Growing Grapes
Grapes have a few requirements. They can grow up walls and over arches, so need little space if pruned carefully. Vines need deep and well-drained soil. They also need a lot of sunlight for optimal ripening. This is why Southern Britain makes a good growing place for grape vines. Soil-wise, grape vines are very easy: they do not really require a particular type of soil.
You can help the soil conditions by preparing the soil site up to a year before planting your grape vines. Remove weeds and mix in organic matter. Dig up soil well to break up any compaction of soil. Make the borders of where you are planting richer with compost or fertilizer. This is even more important for indoor grapes.
For the best results, plant your grape vines between October to March. Weed the surrounding soil regularly, and place vines against walls and fences that are at least 4 feet or 1.2 m away from each other. Rows should be 1/8 m or 5-6 feet apart.
When planting, you will want to remove broken and damaged roots and vines. Place the vine in the soil at the same depth you received it in from the nursery. After planting, prune vine tops to single canes.
During the first year after planting, you should water your grape vines prior to any dry season. Outdoor grapes only need watering during severe and prolonged dry seasons. After the first two years from planting, remove all the flowers from your grape vines. Watch the growth of at least three bunches of grapes before cropping them after they mature. Tying your vines to a stake is also advisable during the first year. This prevents injury and trains grape vines well.
It is advisable to mulch your grape vines during spring. During spring, the soil retains more moisture. Mulching will prevent weeds: use gravel or stones to mulch by placing them 2 to 7.5 cm, or 2 to 3 inches deep around the vine bases. Keep in mind that white gravel will reflect sunlight to the grape vine canopy, whereas black gravel will absorb sunlight. Manure is not a wise choice.
You will read that grape bunches from indoor-grown grape vines will benefit from thinning. Outdoor grape vines, especially those used for wine, should not be thinned.
Pruning and Training Grape Vines
Grape vines, or vines in general, should be grown alongside a supporting system. Wall space wires placed 25-30 cm apart, or 10-12 inches apart are ideal. If you have planted your grape vines in the open outdoor ground, install a different kind of supporting system. Wooden stakes can be driven into the ground and wire can be used for spacing. The wooden stakes should be 1.92 m or 6 and a half feet long, and should reach into the ground by 60 cm, or 2 feet. The stakes should be 3 to 3.6 m apart, or 10 to 12 feet apart. The wire fencing should be built in with 30 cm, or 12 inches spacing.
Early winter, such as late November to December is the best time for pruning. Save other pruning-like practices for spring and summer. These can include fruit thinning, such as described under growing grapes indoors, as well as training and removing new shoots.
There are many systems of pruning, such as the Guyot system – where new fruiting growth emerges from one to two horizontal arms. Another system is the rod and spur pruning system. This is also called the cordon system, as it is often also used for growing indoor grapes of grapes against outdoor walls. In the rod and spur system, fruiting side shoots merge from a main vertical stem such as an espalier.
Try to reserve pruning for early winter, or rather in late November to December. If you wish to thin your fruit bunches or reduce the amount of new, young shoots, save this for the warmer climate of spring and summer.
If you are planting a whole row of vines, choose a south-facing slope with the rows also sloping from north to south.
Growing Grapes in a Container
When growing dessert grapes in a container, grow them in a conservatory and place them outdoors during the winter. Alternatively, they can be planted outside, though the stems and trunks trained to grow inside. If you plant vines like this, they will be much easier to manage: they will need less frequent watering and feeding will be more straight-forward.
When buying plants that have already been seeded, avoid pot bound plants. These will have a messy mass of roots inside the pot that will limit their growth. Look for healthy foliage for summer growth among these plants. This will be green, not yellow.
Growing Grapes Indoors
Indoor cultivation can provide stronger and more reliable crops if you are growing in the northern regions of the UK.
They need careful watering. Frequent watering during grape vine’s growing season is important. However, grape vines grow best when also provided with a feed, such as tomato feed when they begin to grow faster in spring. Feeds like tomato feed are best because they act as a high potash liquid fertilizer.
If you are cultivating grapes inside a glasshouse or conservatory, ventilate it well during bright summer and spring days. Keep the floor a little damp to ensure good humidity, except for when the plants are flowering and when the fruits are ripening. When trying to achieve pollination, shake the branches gently and create a drier atmosphere (by not damping down the floors).
You can thin bunches using scissors (remove a third of the grapes) to improve the ripening process and air circulation. Monitor your grape bunches at least a few times weekly to ensure that there are no diseased and damaged grapes.
A trio of methods are used to improve yield to its maximum potential. These are grape cluster thinning, berry thinning and application of Gibberlin acid. For the home grower, grape cluster thinning is the easiest and most accessible method to improve yield. Pruning should also be done during late Autumn or early spring, depending on the climate zone you live in. Grape cluster thinning allows the development of tight clusters that are more optimal than loose thin clusters commonly seen without grape cluster thinning.
For dessert grapes, the greenhouse should not be heated, and it should be very well-ventilated during cols and still, dry weather until spring begins properly. Potted vines should eb places outside to receive enough cold weather to allow a period of dormancy.
During September, you want to expose the branches to more sunlight and improve air circulation. You can do this by removing leaves carefully and gradually.
Fertilize the plant before the flowers develop. This promotes more fruit to develop.
Common Pests with Grape Vines
Both the glasshouse red spider and two spotted mite cause leaves to become pale and mottled. They will be covered with webbing and will drop before they reach full maturity.
Mealy bugs are small, white creatures that form cottony nests. They target growth points on a plant, forming white meal clusters. These particularly form in harder to reach places such as under loose bark or at leaf joints. Here they eat plant sap and excrete honeydew that appears as black and sooty mould on leaves.
How to get rid of common grape vine pests
Both the glasshouse red spider and two spotted mite do best in arid conditions, so mist your grape vines on a regular basis.
Encouraging ladybirds to live around your plants will decrease the numbers of mealy bugs on your grape vines.
Biological controls represent a group of effective and known measures to reduce insectoid pests that you may be struggling with, such as mealy bugs, two spotted mites and the glasshouse red spider.
Other common problems faced when growing grapes
Grey mould is a fuzzy grey fungal growth. It is also called botrytis and begins as pale or discoloured patches on plants grown in humid conditions. The fungal spores infect the plant through tissue damage, open flowers and open plant wounds. The fungal organism can also attack unripe fruit. Note that these spores can remain dormant and alive as black resting spores throughout the winter period.
When you first notice this mould growing, cut off the affected part of the plant to reduce the chances of spread. Reduce the humidity of your greenhouse via better ventilation. Avoid packing too many plants in a single area, especially when plants are young or are seedlings.
Powdery mildew is another form of fungal infection. It shows on the plant as deposits of white powdery substance across the leaf surface. This can have longer-lasting effects that cause the leaves to have stunted growth and shrivelling.
To avoid the formation of powdery mildew, ensure soil is kept moist. Grow your grape vines in colder conditions if you have persistent problems with powdery mildew.
How to Harvest Grape Vine Crops
Once you feel the ripeness in your grape bunches, they are ready to be picked. They will feel soft when touched and will taste sweet. If the grapes you are growing are green, ripeness is also indicated by a colour change. The skin of the grapes will transition from a deep and dark green to a translucent yellow colour. The skin will also become a lot thinner. It is best advice to always taste the grapes before harvesting them: the sweeter they are, the riper they are. Use a knife to cut the grapes into branches without removing the main stalk.
Have patience when growing grape vines. It doesn’t happen overnight; it may take up to three years for the plant to reach the level of maturity needed to produce ample amounts of fruit. The idea behind harvesting only when fully ripe is that grapes do not improve their sugar composition after harvesting. Once this sugar content has peaked, they will decrease in quality rapidly.
Remember that yield, taste and other characteristics will vary depending on which variety you opt for, as well as the vine’s age and the climatic conditions it is growing in.
Grape Use Tips
After harvesting wine grapes, you have the choice of eating them fresh, though they are best squeezed and pulped to be made into wine (it’s in the name!). On the other hand, dessert grapes should be eaten as soon as possible post-harvest. They are the best type out of wine and dessert grapes for eating, though can also be stored for up to two weeks in the fridge.
It is a good idea to identify why you want to grow grapes, as this will influence your decision on the variety of grapes you choose, which will affect how you grow them. Grapes are highly versatile. The vines can be used as a screen on a glass door for extra privacy; the fruits can be made into grape preserves, grape juice, and wine. The fruits can also be dried to form raisins.
Make sure you purchase your grape plants from a reputable nursery. It is best to receive them in the early spring – upon buying them, plant them immediately following the guidance given above.