Citrus I have known

Listen to a gardening talkback show on the radio here in Sydney and you'd probably think they should just rename it 'The Citrus Show', because about half the calls seem to be from people having problems with their citrus trees. Given the large number of 'sick citrus' phone calls you'd be forgiven for jumping to the conclusion that citrus are difficult to grow. They're not that bad, and in fact I think the 'Citrus Show' syndrome reveals two simple facts. One is that citrus are very popular, so lots of callers want to talk about them. The other is that citrus can be fussy if all their needs are not met. And that's what I thought I'd blog about here. What I've learned about growing citrus here in Sydney (not only from experience of course, but also from reading countless magazine articles about them, too!).

Here's a happy scene from earlier in the year. Cumquat fruit on 'The Twins', the two potted 'Nagami' cumquat trees which are sharing the same sunny spot in my backyard.

Standing back a few feet, here are 'The Twins' last weekend. Happy in their big pots, mulched, in full sunshine, well watered and well fed with chicken poo slipped under the mulch. Sitting up on some pot feet to improve soil drainage. And planted into as good a quality potting mix as I can find.

This is the motivation for growing your own cumquats: making marmalade! My third-ever batch, and every bit as good as the first two. Not a big marmalade eater, so this is a year's supply for me.

Way over yonder down the back, at least 8 metres away from the cumquats, is the new 'Eureka' lemon tree, 18 months old and going strong. It's living in the same spot as its predecessor, a gnarled ancient lemon tree that was full of rot, covered in scale and still producing pretty good crops of lemons despite its thoroughly decrepit condition! I got an arbourist company in to remove the rotten old tree and grind the stump, and after composting and improving the soil, a few months later I planted this baby. Not sure if planting another lemon in the same spot is a tragic blunder or not - only time will tell!

While this might seem to be a repeat of the photo of the magpie at my birdbath at the end of my "Hills are Alive" blog about potato growing, which it is, it also shows two of the major things that lemons need: mulch, and no competition around their immediate root zone. In a crowded, tiny garden this 'no competition' rule is a horrible restriction to live with, so I have compromised and have left the immediate 70cm space around the young tree bare of plants, and will just assess how the other plants nearby (two geums and three hellebores) affect the lemon's health.

Citrus are great for telling you how they're feeling. The moment they don't like their diet, their leaves change colour in various ways, saying things such as "give me more magnesium you fool". These lemon leaves seem pretty happy so far.

Citrus are appallingly greedy things. They need a major feed of chicken manure in late August, and another major feed in late February. There are non-organic 'citrus food' products available, but they don't improve the soil, so I prefer the organic stuff (ie Dynamic Lifter original chicken poo pellets), or at least organic-based stuff such as the Dynamic Lifter chicken poo for citrus, which has some added trace elements. This latter product is not certified pure organic, but it's beneficial for the soil as well as the tree and will do me.

Citrus flowers have a beautiful scent, and combined with the glossy green leaves they make a very attractive garden plant. This is a lemon flower one soggy morning.

Good news, this potted Thai kaffir lime tree is going back to my sister-in-law Laura's place next week. It has bounced back really well from being just a bunch of bare sticks in mid-winter, and it's putting on growth every day here at the Sunny Vista plant rehab unit. Laura's a keen cook, and she misses her lime leaves for making her Thai salads and stir-fries. She's battling away with breast cancer, but her renewed enthusiasm for cooking, plus a good supply of fresh leaves for her to use is great news all round. Go Laura!

These fascinating Thai lime leaves look like they are two leaves joined at the waist. They're amazingly aromatic and, finely sliced, are the heart and soul of so many Thai dishes. These trees do produce fruit, a knobbly weird looking thing without much juice, but the grated zest of the fruit is also a fab Thai cookery ingredient, too.

The only drawback with the Thai lime tree is its thorns. You would never place this tree where passers-by or kids could brush against a branch!

As I was writing this blog it occurred to me that I ought to mention a bit about pests, and thought "I bet there's a bronze orange bug in the Tahiti lime that I could take a snap of."

Sure enough, there were a couple. This is an adult. They're also called stink bugs, because of the smelly (and caustic) liquid they emit when they feel threatened. So you need to be careful if you try to remove them by picking them off, knocking them off, or spraying them with something like a pyrethrum spray, which works well on them.

You almost need to stare at this photo for a moment to see the stink bug here. It's an immature one, which is still a light green colour. It will turn orange when it becomes an adult. As adults, stink bugs can reach plague proportions sometimes, and in the crowded conditions of inner-city areas, where there seems to be a sick citrus tree in every second backyard, it's impossible to be free of these – and many other – insect pests.

The little dark splatters on this Tahiti lime tree are the residues of the organic fruit fly control I am trying out this year. The product is called Eco-Naturalure, and if you're interested in it, I blogged about it earlier this month when discussing Organic Pest controls. All the reports I have read say that, provided you follow the instructions, it works. I sure hope so! Only the next summer and a blog at the end will tell.

With that short tour of my various citrus trees (and check out the previous blog on my espaliered 'Tahiti' lime tree to complete the picture of my backyard citrus collection) I have developed a few opinions on why so many people have problems with their citrus trees, so here goes.

1. Citrus will complain if everything is not to their liking, so if you don't pay attention to each and every basic, ie..

• full sunshine

• good soil drainage

• steady water supply

• mulch

• no competition around their root zone

• lots of food in late winter and late summer

... they will throw some kind of wobbly and either produce a lousy crop or develop some kind of mysterious leaf disease or let the pests run rampant.

2. Citrus pests are everywhere because there are so many unattended, sick citrus trees in suburbia that the numbers of pests is enormous. They're bound to pay a visit to your backyard, no matter how well you grow your own trees. The main pests will be bronze orange (stink) bugs, aphids and fruit fly, but in winter you can expect scale insects, especially white louse scale, to have a go at colonising your citrus, and citrus leafminer making squiggly little lines in the leaves. There are other pests, such as gall wasps, which make lumps on stems, but I just cut them off I see them. These things plagued the ancient lemon tree that I had removed, and haven't been seen since.

3. To prevent pests, you need to look upon spraying not as a "zap them" control, but as a "deter them" preventative. So I use organic sprays as deterrents, and I apply them according to a routine. All through the year I use an organic oil spray (here in Oz you can use Eco-Oil or PestOil) to control scales, aphids and citrus leafminer. I try to apply it regularly, roughly every fortnight, but sometimes that's easier said than done. And in summer I am using the organic fruit fly preventative as a matter of course, applying it often as well, and especially after each period of rain, when it washes off.

4. And to give yourself a good headstart, the best decision you can make is to choose a variety that is suited to your climate. Here in Sydney, for example, the 'Tahiti' lime is the go. Everyone acknowledges that the West Indian key lime has a better flavour, but it's a tropical plant and it will spend most of its life here in the sick bay, if it lives at all. And here in Sydney the 'Eureka' lemon is happiest. In colder spots, the 'Lisbon' fares better, I hear.

5. And finally, I have learned that potted citrus need a different feeding regime by comparison to citrus grown in the ground. Potted plants need lots of little feeds (every six weeks) compared with the two big feeds every six months that the in-ground guys prefer.

And that's my grand unifying theory of citrus growing in inner-city backyards. The rewards are just so wonderfully delicious that I will just keep on trying to grow them no matter what happens.

I love lemons in so many things – squeezed on barbecued souvlaki, fish, chicken, or on schnitzels. And then for desserts I love making lemon meringue pies, lemon and lime tarts, lemon delicious puddings in winter, the list goes on.

And limes! Margaritas, guacamole, tomato salsas – and when Pam wants a cool beer she only drinks Corona (ever since she heard a Lucinda Williams song several years ago she's been a Corona girl) and of course it has a slice of lime in the neck.

And cumquat marmalade for breakfast. After all this blogging about citrus, the chances that I won't have home-made cumquat marmalade on toast are zero, nil, simply not on.

And not growing citrus? Simply not on!