Growing your own citrus trees

by The Listener / 13 December, 2012
Growing your own citrus trees

What’s a home garden without the pleasure of fruit from your own citrus trees?

Bitter or sweet, citrus trees are prized across the world. Where temperatures are too cold to grow them as a garden plant, glasshouses are built in their honour. My husband’s stepdad has only one request for Christmas Day: that in the morning he has a Christmas stocking with a single orange in the toe. When he was a boy, Christmas morning was the only time he saw such a treat.

Here in New Zealand, our climate is warm enough, especially in the North Island and upper South Island, to grow these trees easily in the back garden. The meyer lemon, for example, has been the most-requested plant on garden plans as long as I’ve been at work. So much so that I sometimes take them for granted and never give their needs much thought.

According to Kay Baxter, who has spent years researching fruit trees in New Zealand, the key to successful citrus growing is in understanding that their root systems are quite different from those of other fruit trees. Instead of having deep roots, citrus have a fleshy root system that grows close to the surface, which means they need regular watering and nutrition, and they are intolerant of competition at their roots.

Despite numerous attempts, I can’t get anything to grow beneath my citrus, but Baxter says there’s no need to bother. However, putting mulch around the roots is a great way to help retain moisture and nutrients. Slow-release specialty fertilisers will provide even feeding, but if you want to go old school, make monthly applications of blood and bone, epsom salts and lawn clippings (about 2cm thick) over the roots.

Citrus like a good supply of water, so are best planted at the start or end of winter when constant moisture is most likely to be available to help early root development. In their first season, the trees are best irrigated. Most varieties are generally available at garden centres, but to ensure you get one suited to your requirements, always ask about the root stock used for the grafted tree. If you want to grow the tree in a container or smaller garden, it needs to be on dwarf root stock. Containers are especially useful in colder climates as the plants may need to be brought inside during the cooler months. Have patience when growing more mature trees.

In the first year after planting, the tree’s root system is still getting established, so it pays to remove all the flowers or fruit, because this will give you a better tree long-term. Smaller trees may do better if left to mature for a couple of years without fruiting. Check how many flowers or fruit your trees are carrying. Reducing the load by up to two-thirds will give you better, healthier fruit. This is especially advisable if your trees flower prolifically but drop the young fruit before they mature. In this case, leave only three out of every 10 fruit. Fruit drop also indicates a tree may be stressed, so ensure water and nutrients are supplied regularly.

Citrus can be grown from seed and they will be true to the parent plant (this is how they grow in their natural habitat), but they can take up to 15 years to fruit, so perhaps these plants are something for those with patience and a long-term plan. Tropical in origin, most citrus like a warm growing position, although hardy lemons will grow well in a cooler spot. Remember the roots are of prime importance, so the soil needs to be free-draining.

Heavier soils need to be well-prepared at planting time with the addition of scoria, gypsum and sheep pellets in the bottom of the hole. Place the tree in the hole, but ensure the top part of the root ball it is above ground level so the soil can be mounded up slightly, say 4-6cm, to cover the roots. Remember, though, that mounding means curving the soil layer up around the tree, and a layer of mulch on top will ensure no roots are exposed.

Pruning should be done in autumn, but most trees require very little; just the removal of dead wood and a slight opening up of the branches so sunlight can get in to help improve the crop. If you’re worried about bug infestations, try surrounding the trees with plantings of aromatics such as rosemary, thyme and sage outside the root line. If you notice nibbled leaves, especially on new growth, slugs are the likely culprit.

All in all, we’re lucky to have a climate where citrus will grow happily between subtropicals and deciduous trees in much of the country. And if you have relatives in the UK, send them a postcard of you sitting beneath a healthy fruiting citrus, because sometimes it’s nice to have the greenest grass.

Citrus for your garden

Citrus recommendations for New Zealand gardens from Simon Jurisich of specialist growers Kwan Citrus Nurseries.

Lemon

MEYER: the sweetest all-round lemon and the most popular backyard tree.
LISBON, GENOA: proper lemons with a true bitter taste that is ideal when making lemonade or limoncello or for cooks wanting a strong tangy flavour.

Lime

BEARS, TAHITIAN: very similar fruit; these are the limes you’re most likely to find in a drink.
KUSAINE: not as well known, this lime is a better performer in home gardens and comes highly recommended.

Lemonade

Like a lemon, but can be peeled and eaten or squeezed fresh to have as an unsweetened drink. Grows best north of Nelson. It will grow further south, but it’s a bit slow to take.

Blood orange

One of the most tropical citrus, it prefers temperatures around 30°C in the summer months to get a true deep colour. It will grow in cooler climates, and although the flavour will be good, the colour may disappoint. A new variety, kara kara, is popular in Australia, which has led to increased interest here.

Oranges (navel)

CARTERS, HARWOOD (late fruiter),
WASHINGTON: traditional favourites.
FUKUMOTO, NAVELINA: modern varieties (easy to grow; they have fewer pips).

Mandarins

SATSUMA: puffy easy-peel skins.
ENCORE: tighter skins, but the fruit last longer on the tree.
CLEMENTINE: easy-peel skins, but they’re tighter than satsuma.

Grapefruit

SEVILLE: looks like an orange but very bitter; used for marmalade. One tree is plenty.
GOLDEN SPECIAL: bitter and sweet, as a good grapefruit should be.

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