You can tell newcomers to Nelson by the way they look longingly at citrus left to languish under trees.

To anyone who hasn't grown up with the luxury of homegrown citrus, it always seems so wasteful to let the precious fruit rot on the ground.

Which is why I love growing my own. Citrus seem like the perfect home garden plants, with glossy, evergreen foliage, a sweet summer perfume, and colourful fruit to brighten up the winter garden and fill the larder.

They make an excellent evergreen structural plant and the perfect gift for the person who has everything.

This year I have been planting lots of new oranges, not just any kind but hard-to-get-hold-of seville oranges. They're the bitter sort for making tangy marmalade.

I'm hoping that in a year or so, they'll go into the mix with my lemons, limes, sour kumquats and harwards late oranges for the perfect breakfast treat.

Strange, isn't it, the way marmalade is only good for breakfast? Try it on toast at other times and you'll see why it isn't so appealing later in the day, when your tastebuds have become accustomed to other, less tangy flavours.

But I find it's the perfect way to begin the day, especially in winter, when my other breakfast choice - homegrown tomatoes - is out of season.

And I love the name seville. It transports me to another, exotic, faraway place, of hot sun and intense colours and heady fragrances, a place I'd love to be in the middle of winter.

To me, this is one of the things that makes citrus so appealing. Just when the chill starts to bite, they magically turn from hard green balls to juicy, sweet, bright beacons, beaming out their sun-coloured rays from the winter garden.

For those of you who don't know, seville oranges look like an ordinary, although small, orange. But, like kumquats, they never sweeten, even when ripe.

Named for the Spanish city where the trees line the streets, the seville orange (Citrus x aurantium) is reputed to have been an Arab import to Spain from Asia, the origin of most citrus species.

It was a boatload of bitter seville oranges lost overboard near the Scottish city of Dundee some time in the late 1700s, subsequently retrieved and made into a conserve called marmalade, which is said to have started the whole bitter orange breakfast jam tradition. Prior to that, "marmalade" referred to conserves made from fruits such as quince.

While it has long been popular in traditional Chinese medicine, more recently bitter orange has become a favourite of the self-health market for its active ingredient, synephrine, a somewhat controversial alkaloid you may want to Google.

Although not difficult to grow, like other citrus seville oranges can be fussy if they don't get the mandatory sunny spot and rich, moist but well-drained soil.

In other words, they may not like your garden if it has a heavy Nelson clay soil, so choose your site carefully when planting it or any other citrus. While they like constant moisture around their fibrous surface roots, they also need plenty of sun and don't like to be crowded out by other plants.

And every year among Nelson gardeners, there's a rash of citrus problems, most often nutrient-related or, after a prolonged wet period, the fatal Phytophthora disease.

Last summer's wet start provided ideal conditions for this soil-borne fungus to flourish, inducing the typical symptoms of limp, rolled leaves hanging from doomed plants. Although you can try pruning them back as a remedial treatment, eventually most such afflicted citrus die, their dull, yellowed leaves falling from the dead branches.

Unfortunately, Phytophthora is hard to avoid and is exacerbated by heavy, wet soils and changing soil moisture, typically from dry to extremely wet, as happened last summer.

The good news is that, apart from the occasional cutting-grown meyer lemon, most citrus are grown on Phytophthora-resistant rootstock, generally Poncirus trifoliata, which also produces compact plants, ideal for the home garden.

However, it also has nasty prickles and a tiresome habit of throwing unwanted shoots from below the graft union, especially when the tree is planted a little too deep or mulched around the trunk.

Instead of using compost mulch, try using orange-sized rocks around the base of your citrus to hold soil moisture and avoid rot or rootstock sprouts.

You can easily spot unwanted rootstock sprout by the telltale trifoliate (three-lobed) leaves. Remove it by twisting the shoot off the base of the tree.

And because citrus are gross feeders (a term I love for the amusing images it conjures up), they also need heaps of nitrogen for juicy and (in varieties other than kumquat and seville oranges) sweet fruit.

Most common among the nutrient deficiencies is a lack of magnesium, typically showing up as chlorosis or yellowing between the leaf veins. A constituent of chlorophyll, the stuff that gives plants their green colour, magnesium is one of the trace elements added to proprietary citrus fertiliser mixes.

But the main nutrient citrus need is nitrogen. In an example where too much is probably never enough, no matter how much nitrogen you give your citrus, chances are they could always do with more.

However, rather than use concentrated proprietary citrus fertilisers, I prefer to use a nitrogen-rich animal manure, alpaca poo from a friend's pets being my current favourite for its dry, user-friendly ready-pelleted form and excellent nitrogen-boosting qualities.

What I don't sprinkle around the citrus, I put in a bucket and top up with water to make a liquid fertiliser, the perfect tonic for any tardy citrus. The results have been rewarding, with great crops and healthy trees.

Starting next month, before the citrus go into active growth, I'll give them all their first dose of alpaca pellets ready to wash into the soil for spring.

JOBS TO DO

Plant citrus. Check out supplies from your garden centre. Seville orange plants are available from selected outlets, and the fruit ripens from midwinter onwards and is available from North Island suppliers. The trees are large, vigorous and cold-hardy. If not available, order trees for next year. Look for seed potatoes in the garden centres and start sprouting them inside for early August planting. Hurry along with your winter pruning and planting – spring is coming soon! Give your lawnmower a good clean and sharpen now so you are ready for the first mow next month. Cut old leaves off your hellebores to enjoy the new growth and flowers emerging now. --

- © Fairfax NZ News