Grow your own mandarins

Mandarins are easy to grow, and if you play your cards right, you could have a juicy supply for picking over several months.

Winter isn’t all bad. As the mercury drops, mandarins begin to ripen. And if you’re lucky enough to have room for several different varieties, you can harvest them over a very long season. ‘Satsuma’ and ‘Corsica No.2’, for example, begin to ripen here in New Zealand in April (mid-autumn). ‘Miho’, a compact variety with large, easy-peel fruit, ripens in May. That’s followed by ‘Miyagawa’, a Satsuma type with tangy-sweet, juicy fruit that’s ready for picking in May/June. ‘Silverhill’ has sweet Satsuma-type fruit that ripen in June/July, while at the other end of the season there’s ‘Richard’s Special’ (fruiting from September) and ‘Encore’, with its peak season from November to February (late spring to summer).

Growing conditions

Mandarins like a warm, sunny spot away from cold winds. Soil must be free-draining, otherwise plants will turn up their toes. Citrus trees have shallow, fibrous roots that are prone to drying out, so make sure you provide plenty of water, especially when young, and when mature trees are flowering and developing fruit. Lack of water can cause fruit drop.

All citrus are self-fertile, so there’s no need to plant another citrus tree close by for pollination.

Planting in pots

If you live in a frost pocket, plant your mandarins in containers and bring them into a sheltered spot over winter.

Choose the pot carefully. Terracotta pots are heavy and stable but they’re prone to drying out. Plastic pots are lighter and more manageable – they’re also better at retaining water.

Use good-quality potting mix that incorporates slow-release fertiliser and water-retaining granules. While it won’t be necessary in winter, in the hot summer months mulch the top of the soil to conserve moisture.

Repot your plant every 2-3 years. Either choose a pot that’s one size up or use your existing pot, replacing 30 per cent of the potting mix.

Feeding

Citrus are gluttons for food. When nutrients are in short supply, their leaves turn yellow and they crop poorly. Little and often is best. For trees in the ground, start feeding with a specialist citrus food from September (beginning of spring) at six-weekly intervals. Continue until March (late summer), giving your trees a rest over winter. For potted citrus trees, apply a slow-release fertiliser in September and again in summer and give them a monthly feed of liquid fertiliser too.

Pruning

Unless you want to shape your trees, mandarins, and other citrus trees, do not need pruning, except for the removal of dead or diseased wood and any suckers. Heavy pruning is undertaken only when you want to rejuvenate a tired tree.

Harvesting fruit

Mandarins change from being immature to mature, and eventually overmature, while still on the tree. But the changes are slow and spread over several weeks. They will keep much longer on the tree than if picked and stored, and they don’t ripen once picked.

The only way to determine maturity is to taste the fruit. Fruit colour doesn’t necessarily indicate ripeness. They may be orange but they may still be very tart.