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All you need to know

Grapes

Due to their delicate skins, imported grapes need more packaging than almost any other fruit – effectively doubling their carbon footprint. But there's no need to buy long-haul produce – just follow Neil Wormald's guide to growing them at home

Whether you’re making your own juice, raisins or wine from them, or more likely just enjoying them as they are, there are few crops as satisfying to produce as home grown grapes.

The hanging clusters of fruit grow on deciduous climbing vines which also produce mid-green, maple-like leaves (these often take on rich and colourful hues before falling in the autumn) and clusters of yellow-green flowers outdoors in May, or a little earlier under glass. Bunches of grapes are notoriously very expensive to buy in the shops and, for this reason, its well worth growing a grapevine at home. Fortunately, there are a wide range of varieties that can either be raised in a greenhouse, outdoors or both.

Furthermore, the vines crop reliably well and take up relatively little space when they are pruned and trained properly. If you want to have a go at growing grapes, then now is the perfect time to start, as they are quite happy to be planted in winter.

To perform well, all grapevines need as much warmth and sunshine as possible. For greenhouse-grown grapes this should not pose any problems but outdoor varieties perform best when positioned against a south or west-facing wall or fence. Grapevines (indoors and outside) also require a good root run in a freedraining soil which ideally has a pH of 6.5 to 7 – this can be determined using a cheap soil testing kit available from any garden centre. The soil is best prepared about a month before planting so it has time to settle. Dig over a 60 x 60cm planting area to a depth of at least 30cm and remove all weeds, before incorporating plenty of garden compost (or John Innes no. 3 compost) into the earth. Afterwards, rake a granular fertiliser into the ground. Outdoors, it’s very important to dig the planting area at least 30cm away from the wall or fence base, as the soil will be naturally less dry.

The stems of the grapevines will require a support system to be trained against and this should be installed before planting. Simply fasten horizontal wires (1.8m in length) every 30cm up the wall (or greenhouse support structure) to a height of 150cm and secure in place with vine eyes. The wires should also be held 10–15cm away from the wall (or glass), as this ensure good ventilation around the stems.

Grapevines are usually bought as container-grown specimens and the ideal time for planting is between mid-autumn and early spring – always position and plant each grapevine in the centre of a system of wire supports. All grapes are self-fertile so, if space is limited, it’s worth remembering that only one plant is required to produce a crop of fruits. However, cross-pollination with another variety is usually recommended and, if you want to grow more than one plant, space them 1.8m apart. When planting, the rootball must be watered thoroughly and buried to the same depth as in the original container. Always firm it in well, before watering once again and spreading a mulch over the surrounding ground (it must not touch the stem base or the moisture may lead to the plant rotting).

Greenhouse grapevines are usually planted in the border soil but, if the structure has a concrete floor, you may have to consider planting the grape rootball outside and then train the vine back inside through a hole in the glass – this is best achieved by removing one of the glass panes and replacing it with a piece of exterior plywood with a hole inside for the stem. The main ongoing difference between them is that grapevines planted outside require less water. Those in the greenhouse border soil start into growth a little earlier in the year and you have more control over feeding and watering. Alternatively, greenhouse varieties can be planted in large pots.

The best way to grow a grapevine is to train the stems against an outdoor wall, fence or the greenhouse support structure. This allows you to easily control the vigour of each plant and ensure a good crop of fruits.

Unfortunately, there are many methods of training grapevines and these can be rather confusing and off-putting. However, some are extremely straightforward and these include the Guyot system, which is probably the easiest to grasp. For ease, choose a grapevine with three strong stems and, after planting, carefully bend the two outer stems downwards and tie them horizontally to the lowest support wire – one on either side of the plant. The remaining central stem should be cut down to its third bud. During the main growing period, the horizontal stems will produce sideshoots and these should be tied vertically to the wires as they grow upwards – pinch out the growing tips when they reach the top wire. The bunches of grapes will form on these shoots. The pruned central stem will develop three shoots (from the three buds) and these need tying-in too. After the grapes have been harvested, prune out the two horizontal stems and their sideshoots – this must be done in the dormant winter period, otherwise the sap can ‘bleed’ excessively and weaken or kill the plant. The three central shoots (stems) can then be used as replacements to start the system again – bend the two outer stems down to the lowest wire and prune the remaining stem to three buds in height.

Once established, outdoor and greenhouse grapevines should be kept lightly moist throughout winter. To ensure maximum light exposure in the growing season, clean the glass behind the stems of greenhouse varieties. Also try to leave the structure unheated through the winter months and then maintain a temperature of 16–21°C in spring and summer by damping down and ventilating the greenhouse.

In early spring, feed all grapes with organic Growmore (or a similar multipurpose fertiliser) and apply a 5cm-thick mulch of well-rotted compost around the base of the plants – this will help to prevent weed growth and conserve moisture in the soil. In the late spring, it’s a good idea to lightly shake the stems of greenhouse grapevines at midday or lightly dust the flowers using a soft artists’ paint brush – this helps to ensure flower pollination and a good crop of fruits. In spring and summer, grapevines also need plenty of water during dry or warm conditions and all weeds should be removed. In the early summer, don’t forget to apply greenhouse shading paint to the glass as this will prevent the leaves and fruits being damaged by sun scorch. A liquid feed with a high-potash fertiliser is beneficial from the moment the fruits form until they show colour.

However, always avoid overwatering (and stop feeding) when the fruits are maturing and ripening or they may split. On outdoor grapevines, bird protection is very important when the grapes begin to ripen – simply drape netting over the plants.

Grapes are usually ready for picking from late summer to late autumn and the best test for ripeness is taste.

The ideal way to harvest grapes for wine making is to simply sever the stalk an inch or so above each bunch of fruits. For dessert varieties, the main stem should be cut on each side of the bunch’s stalk to create a short woody handle – prune the stem so that it is 10cm in length on one side of the stalk and 20cm in length on the other. This will allow the fruits to be stored for several months.

Fill some clean bottles with water, place in a wine rack in a cool, dull room and then insert the longest end of a woody stem (also called a handle) into each bottle, so the bunch of grapes hangs downwards. After harvesting, reduce the amount of watering until the vine becomes dormant again.

Month-by-Month

  • January

    Plant new grapevines but, for outdoor varieties, only do this in mild weather and when the soil conditions are suitable. In March, also give established grapevines a feed, and add a mulch – but don't let it touch the plants' stems.

  • February

    Plant new grapevines but, for outdoor varieties, only do this in mild weather and when the soil conditions are suitable. In March, also give established grapevines a feed, and add a mulch – but don't let it touch the plants' stems.

  • March

    Plant new grapevines but, for outdoor varieties, only do this in mild weather and when the soil conditions are suitable. In March, also give established grapevines a feed, and add a mulch – but don't let it touch the plants' stems.

  • April

    In dry weather, water grapevines and remove all weeds. On hot days, damp down and ventilate the greenhouse.

  • May

    Hand-pollinate the flowers of greenhouse-grown grapevines using a soft artists' paintbrush and apply greenhouse shading paint to the glass. In dry weather, water grapevines and remove all weeds. Damp down and ventilate the greenhouse.

  • June

    Apply greenhouse shading paint to the glass. In spells of dry weather, water grapevines and remove all weeds. Keep damping down and ventilating the greenhouse.

  • July

    In dry weather, water grapevines and remove all weeds. Damp down and ventilate the greenhouse. Give grapevines a liquid feed. Thin the fruits in each bunch of grapes. In August also harvest the ripe fruits and store some for future use, and protect outdoor grapes from birds by using netting

  • August

    In dry weather, water grapevines and remove all weeds. Damp down and ventilate the greenhouse. Give grapevines a liquid feed. Thin the fruits in each bunch of grapes. In August also harvest the ripe fruits and store some for future use, and protect outdoor grapes from birds by using netting

  • September

    Continue to harvest the ripe fruits and store some for future use. Protect outdoor grapes from birds using netting. In autumn you can start to plant new grapevines.

  • October

    Continue to harvest the ripe fruits and store some for future use. Protect outdoor grapes from birds using netting. In autumn you can start to plant new grapevines.

  • November

    Plant new grapevines. Prune established grapevines and clean the greenhouse glass to let more light in.

  • December

    Plant new grapevines but, for outdoor varieties, only do this in mild weather and when the soil conditions are suitable. Prune any established grapevines.

Next
Fruit Thinning

Fruit Thinning

For the best harvest of grapes, allow one bunch to form for every 25–30cm of vertical sideshoot. The fruits in each bunch should also be thinned – essential for dessert varieties but not for those used for wine making. When the grapes are about the size of a pea, use a pair of long and thin-bladed vine scissors and, working from the bottom of a bunch, remove two out of every three grapes – this will give the remaining fruits a chance to swell and ripen. To avoid removing the ‘bloom’ from the grapes – this spoils their appearance and makes fungal diseases, such as grey mould, more likely to set in – try not to touch them with your hands. A good way to avoid handling grapes is to use a small, forked stick to hold them. It’s also vital to examine the developing bunches regularly and remove any fruits that are split or damaged.

Grapes: Varieties To Try

  • Black Hamburg

    An early-ripening Sweetwater variety with a display of small green flowers throughout June and July. It is easy to grow – both inside and out – and has juicy dark-red or purple fruits.

  • Muscat of Alexandria

    Late-ripening white dessert grapes with a rich and very sweet flavour. This variety does particularly well in pots.

  • Gloire de Boskoop

    A heavy cropping dessert grapevine for a wall or training over a pergola. The soft-fleshed blue-black fruits are picked in September and October and the sweet flavour is outstanding.

  • Polo Muscat

    This reliable and disease-resistant yellow-green (white) dessert grape is a relative newcomer. It is ideal for growing against a wall and has delicious fruits in August and September.

Growing in Containers

Many grape varieties, especially greenhouse types grow extremely well in containers, such as wooden half barrels. They should have a wide bottom (for stability), plenty of drainage holes in the base and be filled with a 7.5cm layer of broken crocks to aid drainage, followed by John Innes no. 3 compost. During the main growing period, grapes in pots need to be kept consistently damp and fed once a week with a liquid fertiliser.

Grapes

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