Kiwi Fruits are surprisingly hardy and there are varieties that can be grown with only a little extra protection in most of the UK. This fruit is perfect for polytunnel growing as it will love the extra warmth and protection from chill breezes and is easy to trail to fit the space you have available for it.
The first thing to bear in mind when selecting your kiwi fruit is that some varieties are self-pollinating while others are not. With the latter you would need a male and a female plant, so it is important to know whether or not the plant you are looking at can be grown alone, especially if you only have a small amount of space to play with.
Kiwi fruit's vining plant will grow best in rich, fertile, well-drained soil. The ideal time to transplant these into their final growing positions is in the spring, as soon as the soil and the air temperature have risen sufficiently. Kiwi varieties should be given a spacing of around 3-4.5m between plants, except in the case that you need a male to pollinate the females, (one male will do the job for up to eight) in which case the make should be around 60cm away from one of the females. Of course a self-pollinating one is the best option where space is limited.
Immature plants and young shoots as the plant grows in the spring can be particularly vulnerable to the frost and so it is a good idea to have some horticultural fleece handy if cold weather threatens early in the spring. Mulch the plants with a good quality compost or well-rotted manure, taking care not to contact the stem as this can encourage it to rot. When growth starts in the spring, you can give plants a boost with a general purpose organic fertiliser or home made plant feed such as compost tea.
Pruning kiwi fruits in summer is important as it will help to create an appealing and open shape and improve air circulation. Improving air circulation can help to prevent some common mildew problems. In a polytunnel, it could be a good idea to train kiwi fruit vines over an archway rather than in a more traditional espalier.
Plants will produce fruit three or four years after planting. The fruits should be picked before the first frosts and placed with ripe fruit in your fruit bowl to encourage ripening. Ripening may take several weeks. Harvested fruit will keep for up to three months in your fridge.