The lemon tree is an ideal fruit-bearing specimen for Sydney gardens, as it thrives in our mild climate. Lemon trees came to Australia with the First Fleet in 1788. There are several main types. 'Eureka' is the most commonly grown cultivar and it has fruit and flowers almost all year round, though the heaviest crop is in winter. It can grow about 4-6m tall. 'Meyer' is smaller, with more compact, sweeter fruit, and is very suitable for pots. Another cultivar is 'Lisbon', used by commercial growers and suitable for hot areas, but it does have thorns.
All citrus trees have particular requirements to do well. A key point seems to be to find the ideal spot in your garden for them - in a well-drained position in full sun. As with any planting, the soil should be prepared in advance, by digging over a reasonably sized area to at least a spade's depth, adding gypsum if there is a lot of clay and incorporating rotted organic matter. The roots of the plant should be teased out gently and the plant placed in a hole at least twice the width of the root ball. The plant should be put in at the same depth it was in the container, with top of the rootball should be level with the surrounding soil. Water well and keep it well watered for the next few weeks. Once established, citrus trees need regular watering and love to be fed every few months, using something like Organic Life or Dynamic Lifter. They also need to be free of competition from grass growing around their surface roots, so a good-sized area should be left clear under the tree, which can then be kept covered with an organic mulch to conserve water and protect the roots from heat. The mulch can be scraped aside whenever you are going to apply fertiliser. Don't ever allow the mulch near the trunk, as this can cause fungal problems.
Young plants should not be allowed to fruit for the first two years, as apparently this will severely affect their growth during that time. To produce larger fruit on established trees, it is a good idea to remove some of the young fruit when it is very small, or even take off some of the flowers. Although pruning is not essential (except to remove dead wood), they don't object to pruning and this is one way to reduce the number of fruit on the tree. Pruning can also be used to produce formal effects such as standards or espaliers out of your citrus trees. Very old lemon trees can be severely pruned in spring. Fertilise and mulch after the big prune and it should rejuvenate, even though you may not get fruit the first season afterwards.
Citrus trees, especially the smaller types such as 'Dwarf Myer' and 'Lots A Lemons', can be grown successfully in pots, repotting as they grow until they finally are placed in a decent-sized container. Once the final size of container is reached, repot every three to four years, pruning congested roots that were at the edge of the pot and teasing away tired potting mix then repot with some fresh potting medium. As with citrus planted in the ground, they need regular fertilising and watering. Keep potted lemons well fed during the warmer months with a granular fertiliser every three to four months and a dose of Seasol every four to six weeks. Put a layer of mulch on top of the pot but keep it away from the trunk. Water regularly but don't overwater (as this will leach our nutrients from the soil). Don't have a saucer under the pot that can collect water, as this may cause root-rot. It seems it is best to keep the canopy of a potted lemon pruned to the diameter of the pot. Make sure the pot is in a sunny position and protected from strong winds that can dry out the pots and damage the flowers.
There are various pests which attack citrus - not all affect the fruit, but they can distort the foliage. Eco Oil can be applied on a regular basis to control most of the pests, which include citrus leaf miner (prevalent in summer and autumn), the horrid bronze orange bug (which can affect the fruit as well as the foliage), scale and aphids. There are also sticky traps available to hang in the tree to attract the male citrus leaf miner in order to reduce overall population numbers; this pest is particularly active from December through to April. When establishing a new tree, it is important to control citrus leaf miners, as they will severely affect its growth.
Branches of the tree laden with lemons can make a spectacular arrangement in a large vase!