Pomegranates are usually associated with much warmer climes, so you may be surprised to learn that these fruiting trees are surprisingly hardy and can do well in a sheltered spot in most parts of the UK. Cultivars such as 'Provence' can tolerate temperatures down to -15 C when grown in a sheltered spot. In most parts of the UK, unheated polytunnels could comfortably accommodate a pomegranate throughout the year and give it the growing conditions it needs to fruit reliably, even when the British weather leaves something to be desired. Be sure to choose the correct, hardy variety as most pomegranates will not fruit reliably in the UK unless you have a tropical greenhouse.
Pomegranate trees will not always fruit reliably when grown from seed and you will have to wait a number of years to find out whether they will. For this reason, most people choose to grow pomegranate trees from saplings, or from cuttings. Cuttings should be taken in the spring and are generally around 25cm in length.
The good news for those with limited space in their polytunnel is that there are various size options for pomegranate trees. It is possible to choose a normal sized tree or to plump for a dwarf variety. Dwarf pomegranates can easily be grown in containers, or in the ground of your polytunnel. Containers, if used, should be filled with a good quality compost and the ground should be fertile, rich in organic matter and well drained.
Pomegranates have glossy foliage and vibrant, funnel-shaped, long-lasting, orange flowers over the summer months. Fruits form at the base of the flowers and should ripen in the autumn when the conditions are warm enough for them to do so. For reliable fruiting, extra heat in this portion of the year may well be required, so either heating your polytunnel or taking plants into a light and warm indoors area may be necessary in some parts of the UK. For ease of movement, it is, of course, a good idea to grow pomegranates in a container.
A good, organic mulch will help to retain soil moisture and help feed the trees. Water well during the summer months.
Pruning pomegranates is not usually necessary. If you do decide to prune for shape then remember that pomegranates fruit on wood that is more than a year old. If you over-prune then you could remove all chance of fruit for quite some time.
Pomegranates can be harvested in the autumn with secateurs when the crown at the base of the fruit has become curled and brown. Scoop out the flesh and seeds and scatter them over your salads, breakfasts, or desserts.