Owen Pidgeon: How to grow citrus plants in pots to beat Canberra frosts

These days there are many units and townhouses with only small spaces for gardens. Some lovely plants can be easily grown in pots and many herbs can be planted out in planter boxes. Today the focus is on how to grow your own fruit in courtyards, where all is paved but there are lots of options.

For many people, the courtyard provides that essential combination of sunshine and protection from the cold winds. Brick walls provide an additional source of radiant heat, keeping the ambient temperature up throughout the cold winter nights. So you ask: what can be grown in large terracotta or wooden half-barrel tubs?

Citrus comes to mind first. In all highlands regions where the overnight temperatures fall below zero and where late winter winds bring sharpness and bruising effects, a sheltered location is just the thing for those fruits that would otherwise struggle to survive.

You will need a good source of wholesome soil for potting up your trees. I have seen some pretty ordinary examples of gritty, clay-based soil with some sheep droppings mixed in to dupe customers into believing it was a premium garden soil. Take care to source your loam-based soil from a reputable supplier as the future of your tree depends so much on having a good, healthy soil. Add in some home-made compost to provide lots of humus and a home for the earthworms and soil microbes.

Make sure to buy a pot that is large enough to house the root ball and allow the roots to spread. Also be careful not to buy a terracotta spot with a narrow base or there is a risk that the whole unit will topple over if bumped or blown by a gush of wind. If you have the space, the half oak barrel is ideal as it allows you to create quite a garden, even growing some little herbs around the rim.

Citrus is a great option for growing in large pots, especially in regions with plenty of winter frosts. You can position the pots close to doorways so you can enjoy the opening of the little white, star-shaped flowers which add to the scented aromas of the evergreen leaves. Our two lemon trees are carrying a good crop of half-grown lemons, as I write.

Citrus have shallow root systems so you do need to keep the surface of the soil free from weeds. Mulch well (but leave a 10mm ring around the stem of the tree to avoid any stem rot). Grow citrus in quite rich soil with plenty of compost added. Add in some poultry manure in August and February to the soil, around the drip-line of the tree.

Citrus originated in Asia but were taken to Arabia and the Mediterranean countries many centuries ago. They were widely planted in Italy and were very popular around Naples by the second century AD. Lemons arrived later than other citrus into Europe, reaching Palestine and Egypt by the 10th century. Columbus certainly knew of the lemon in Genoa when he embarked on his explorations, as he planted the seeds of lemons across the islands and coastal regions of the New World.

The question of how to grow the hot-climate lemon trees and other citrus in lands with cold winters was answered by the rich European gentility in creative ways. They invented the orangerie, which were special winter houses to protect their delicate trees. The citrus were grown in large planter boxes and the boxes were moved inside before winter set in. Plenty of work opportunities for gardeners in those times.

You too can move your boxed or potted citrus to the warmth of a brick wall facing north or close to your house or apartment, with the paving bricks absorbing the warmth of the sun and radiating this warmth out overnight.

Remember that citrus will push out new tips before the cold winter and early spring days are over. Do not undertake any pruning of old foliage because it will serve as a protection from frost for those new tender tips. If you do need to leave your citrus tree away from permanent protection, then you can use a bolt of hessian to warp around the tree.

The 'Meyer' lemon with its pale orange-coloured fruit is a good ornamental variety to plant in your half oak barrel. It will produce a crop across most months of the year but it is not as sweet as the more frost tender 'Eureka' or 'Lisbon' varieties.

The emperor mandarin and the sublime lime are other good citrus options for small gardens and patio pots. Wheeney grapefruit will also produce a crop of good-sized fruit in the highlands regions, if provided with some frost protection.

Figs will also grow well in pots. You can keep them well pruned, both in height wise and/or spread. Figs produce most of their fruit on new season's growth so if you keep them well-trimmed each winter, you can still enjoy a bountiful crop in the coming season. 'Black Genoa' is the large dark purplish variety that produces both an early summer (breva) crop and the main, late autumn (higos) crop. 'White Genoa' and 'Prestons Prolific' are two other high producing cultivars.

A small number of quality on-line nurseries in the southern states provide a good selection of bare-rooted deciduous fruit trees over winter. They will pack the small trees in damp wood shavings and send by the postal system. Try Heritage Fruit Trees west of Ballarat, Yalca Fruit Trees east of Echuca, in northern Victoria, and Woodbridge Fruit Trees in the Huon Valley in Tasmania. It is worth taking a few minutes to look at each of these well-established specialist nurseries as they offer online ordering for many fruit species, including quite rare cultivars.

I shall write more next week about selecting other fruit trees for winter planting.

Stuffed baked apples with lemon syrup

6 medium apples
40g butter
1 tbs brown sugar
100g sultanas
2 tbs chopped walnuts
2 tbs lemon juice
1 cup water

Lemon syrup

2 cups water
⅔ cup castor sugar
2 lemons, juiced
grated zest, from 2 lemons

Remove the apple cores using an apple corer. Preheat the oven to 200 C. Mix together the butter, sugar, sultanas and walnut pieces. Press the mixture into the centre of each apple, filling all the space where the core was removed. Place the apples into a medium-sized baking dish. Mix the lemon juice into the cup of water and pour over the apples. Cover with foil and bake for 35-40 minutes until the apples become tender. Remember to brush the apples with the juice occasionally during the cooking.

Combine the water, castor sugar, lemon juice and zest in a small saucepan. Apply medium heat and simmer until the syrup is reduced to approximately one cup. Serve the apples while still warm, ladling a generous serving of syrup over each apple.

This week in the garden

* Take the opportunity to plant out some onion and leek seeds into propagation trays. Plant mesclun salad mix directly into the garden and provide a raised plastic canopy to trap the daytime heat.

* Plant out some garlic cloves over the coming week. The longer that garlic can grow over the autumn and winter months, the stronger will be their rooting systems. Weed around earlier plantings and then mulch with pea straw or organic sugar cane mulch.

* Prepare a deep, rich garden bed to plant out new rhubarb sets and asparagus crowns. As these root based crops will stay for some years in the one location, a well prepared bed will require plenty of mature compost and well aged animal manures.

* Make plans for planting out fruit and nut trees. Take note of the extent of direct sunshine and consider providing protection from strong westerly winds, using windbreak plants or a cover wall.

Owen Pidgeon runs the Loriendale Organic Orchard near Hall.