Grapevines in Pots
Present-day gardeners would have had a hard time surpassing the efforts of the estate gardeners of Victorian England. Fruit wasn’t easily shipped long distances in those days, so it took real work and creativity to find ways to make fruits available on demand by His Lordship during the “off” season. It was a test of status among estate holders as to who had the most elaborate gardens, the best plant collections, and could have fresh fruit in the greatest variety at untypical times and in unusual ways.
One fruit that typified the effort that went into this production of off-season produce was grapes. Victorian gardeners found ways to extend the season at both ends, to make fresh grapes possible all year round. Most of these tricks included a warm greenhouse, but one trick was to take a living grape cane from an older vine, and train it through the hole in the bottom of a large pot of soil. Because it was still attached to the parent vine, the cane would be able to produce fruit.
At the same time, it would root in the soil of the pot. By the time the fruit was ripe, the potted vine could be cut loose and was then used as a banquet table centerpiece from which guests picked dessert on the spot. This sort of presentation of potted vines or other fruit was common enough that some banquet tables were built with a hole in the center to accommodate the pots.
||The classic English container grape is the vinifera variety ‘Black Hamburg’, an excellent, attractive, though seeded, black grape with large meaty berries. Its offspring ‘Muscat Hamburg’ though somewhat irregular in cluster, is unsurpassed in flavor. Other vinifera varieties worth trying in pots are ‘Delight’, a white seedless with a more compact vine than most; ‘Early Muscat’ an intensely-flavored white grape; ‘Beauty Seedless’, a large-clustered blue seedless grape; and ‘Emperor’, a late red grape that will store well. Many of the seedless vinifera varieties, such as ‘Thompson Seedless’ and ‘Flame Seedless’ are not well suited to pots.
By growing grapes in pots, obviously you have plants that can be moved to a warmer location when the weather turns cold. Just make sure wherever you put your grapes they get bright sun, but the root systems can’t get too hot. Black or dark plastic pots draw heat to the soil and can hurt the roots when placed in full sun, so in warm seasons try and place the plant so that the upper plant is in full sun, but the container itself is in the shade. Or you can put the plant in a wooden planter to keep the sun off the roots.
Grapes like good silt loam soil, that is kept moist, but not soggy, and very little fertilizer. A low nitrogen fertilizer, such as fish emulsion, applied three times in a growing season usually suffices. Stop fertilizing by mid-summer to slow the vine growth and help the fruit ripen.
Train the vines on stakes or something like a fan trellis. Classic English vines were usually trained with a central trunk about three feet tall with short fruiting spurs coming out of it at intervals of six inches or so. After bloom time, especially when the vine is young, thin the fruit clusters to prevent overloading the vine. Start with one or two clusters when the vine is a year old, and allow another one or two each year until you reach a maximum of one pound of fruit per gallon of pot. Each winter, the dormant shoots of that season’s new growth will be cut back to spurs having one or two buds.
All but a few grapes are self-pollinating, though shaking the vine at bloom time helps insure good set. Be sure to smell the flowers too. Grapes have a wonderful, sweet scent in flower. When the fruit is ripe, sit back and imagine yourself in Victorian England!
It is possible to grow grapevines in pots, however vines thrive better when grown in the ground.
The smallest grapevine variety for perennial pot cultivation, for pots < 10 litres.
A compact, small, perennial variety, which can be trained in various cordon systems, for pots >10 litres.
Ornamental Grapevine (“Prachtrebe”: literally translated “Magnificent Grapevine”)
This is rather an ornamental variety of vine for florists and mostly an annual plant. Bears large crop of fruit in the 2nd year, perennial thereafter with reservations, for pots > 10 litres, requires heavy fertilising after flowering.
Overwintering is possible in a cellar or similar storage room (or an unheated shed), as long as the pot is kept moist and the temperature remains well and truly below the critical 12ºC limit. Otherwise, bud burst will occur prematurely and the plant may die. In modern cellars, the temperature is usually not low enough, unless the cellar is unheated and permanently aerated.
If the vine is overwintered in a glasshouse or similar, it must be transferred outdoors early (around end of February). It is imperative to prevent premature bud burst under the glass with subsequent transfer into the open. Plants which have already burst bud must only be transferred to the open from April / May, because the young shoots are very susceptible to frost.