Grapes are found naturally in harsh conditions and are tolerant of drought. Some of the best grape-growing areas in New Zealand are naturally stoney areas, such as the Gimblett Gravels, which are old dry riverbeds in the Hawke's Bay, and the alluvial schist gravels of Central Otago. The key to a good grape crop is to ensure vines get enough water when flowering. After this point, mature vines will be fine with little water. Grapes rarely require fertiliser and are great candidates for biodynamic practice. If your vine is growing and fruiting well, there is no need to fertilise the plant. Otherwise, apply compost and a balanced organic fertiliser and a dash of mineral-rich rock dust.
Prune grapes in winter, once the plants are dormant. Select new, strong growth and remove weaker stems and any dead material to ensure strong growth the following season. There are a couple of pruning techniques depending on the variety of grape and the structure you are growing it on. Grapevines are traditionally pruned in a T shape or cordon, supported along a fence or wall. The strongest shoots are allowed to grow to form the structure. Each year, cut the growth off the T-shaped vine, leaving short two-bud stubs every 30cm or so, which will produce fresh new growth in spring.
Some varieties require cane pruning. Select two to four strong canes to grow on from the T-shape structure, rather than cutting canes back to stubs. Tie these horizontally along the wire or pergola. You will find out which mode of pruning suits your grape if you have pruned back hard in the past, but the vine went on to produce vegetative growth and no fruit.
Grapes are a delicacy and can be expensive if you don't grow your own, but are an easy and wallet-friendly plant to grow. Excess fruit can be made into juice by cooking the fruit then straining with a muslin cloth or an old (clean) pillowcase. Grape skin contains polyphenols which are good for heart health. The skin, juice and seeds of red grapes contain the greatest quantity of this compound. You might even delve into home wine production and follow in the footsteps of the world's wine-loving ancestors.
Get the juice a little grape history
* Wild grapes are thought to have originated in central Asia in the forests that grew on the southern shores of the Black and Caspian seas.
* Wild grapes are dioecious (male and female plants must grow near each other to ensure pollination). Cultivated grapes are hermaphroditic and can fertilise themselves.
* A clay cuneiform tablet made by Sumerians was found in southern Iraq and is the first literary evidence of winemaking.
* The boundaries of the invading Roman Empire directly related to the range of where the grape could be cultivated, along river valleys such as the Rhine, Rhone, and Danube, which suited the grape very well.
* Christopher Columbus took European vines (Vitis vinifera) for planting to the "New World" in 1493. European vines soon flourished in Central and South America.
* Native grape species are in America. The European and American vines hybridised, creating the grape gene base for parts of the world not suited to the European vine. This hybrid was resistant to the green fly aphid which wiped out European vines in the 1800s.
* For interesting table grape cultivars which include old New Zealand heritage grapes, (such as Bishop Pompallier brought to New Zealand and planted in Northland in the 1850s), see Edible Garden's catalogue. It includes Koanga Garden's heritage collection. Wairere nurseries also have a selection of grape varieties which include heritage varieties.