How to grow healthy citrus trees
Tools for the job
- Metal rake
- Spade and/or shovel
- Hollow-tined corer
- Watering can
- Garden hose & fittings
- Sprinkler or fixed watering system
- Selected citrus tree(s)
- Mulch or compost
- Complete citrus food (fertiliser)
- Insecticides/pesticides (as requested)
Step 1: Selecting
The range of citrus trees that can be successfully home grown extends beyond the popular lemon. Here are some other popular varieties for you to try.
Step 2: Purchasing
Citrus trees with glossy, deep green foliage indicate a strong, healthy plant. So avoid buying any young tree with leaves that show any signs of paling or yellowing – they may be suffering from a lack of nitrogen. Check for rotting or decaying of the stems bark where the stem meets the potting mix within the container. This is called “collar rot” and these trees should be ignored. Look also for any sign of insect or pest attack, or discolouration that may be caused by fungal disease.
Step 3: Garden position
Citrus trees love heat. They do best in a warm, sunny position protected from frost and in well-drained soil. If the patio is your only sunny area, why not grow a citrus tree in a big tub? Wine barrels cut in half are perfect or choose from the wide range of large plastic and terracotta pots available. Generally, the country’s warmer northern areas will produce better quality fruit than in southern regions, provided the trees are well-watered during hot, dry summer periods. But this does not mean that citrus do not grow well in temperate regions. Lemons and grapefruit, for example, thrive in cooler areas but oranges and mandarins, while they can be grown, may not ripen so well. Most citrus trees are frost tender, especially lemons and mandarins. In very severe frosts, the bark on lower limbs as well as the main trunk may even split, allowing infection of wood-rotting fungi. Drainage must be good. Citrus are susceptible to waterlogging and root rot can occur if the plant is subjected to long wet periods. Choose a deep, sandy-loam type well-drained soil if possible, although a loamy soil that is well-drained is sufficient.
Step 4: Planting times
Citrus are available most of the year. In tropical and subtropical areas they can be planted anytime. In the southern states they are best planted September to May after the danger of frost has passed.
Step 5: Planting
Young citrus trees from most Mitre 10 stores are usually sold in the plastic grow bags or plastic pots. When you get your tree home and if you do not plan to plant it immediately, prevent the soil or potting mix around the roots from drying out. Give it a good soaking the day before planting, so that the soil does not fall away from the roots as you place it in the hole.
To plant your tree, dig a hole wide and deep enough to accommodate the whole root system. If the subsoil is heavy clay, be careful when digging that a saucer, or hollow, is not formed in the bottom which can fill with water and possibly drown the root system. To prevent this problem occurring, plant the tree onto a slight mound built up above the surrounding soil level, or install some type of underground drainage before planting.
Place the tree in the hole, making sure the bud union is well above soil level. (The bud union is the slightly swollen area on the lower main stem where the variety of citrus is budded onto the rootstock below). Do not place any fertiliser below the root system at the planting stage – fertilising comes later when the new growth appears. Then cover the root system with soil, ensuring that the tree is upright and straight as you backfill. Firm the soil in around the roots as you go to get rid of any air pockets and water thoroughly when the hole is around half full. Then continue in the same way until the hole is filled and water in thoroughly again.
Step 6: Care and maintenance
All citrus trees need plenty of water during their main growing periods of Spring and Summer. Moderate watering occasionally in Autumn and Winter may also be needed. But it is during the dry, hot summer months that it is important to keep the soil moist at all times with deep soakings. Light waterings only result in fine surface feeder roots dying when the soil dries out. The best way to keep your tree always well-watered is to install a drip watering system. These are easy to install yourself, low-cost and highly efficient. Mulching will also help to prevent drying out. Simply spread an organic mulch of composted poultry or animal manure, straw litter or the like over the surface directly under the drip line of the tree. It will help to suppress weeds and improve soil structure as well. Take care to keep mulch away from the base of the tree.
Citrus need fairly large quantities of fertiliser. Use a complete citrus fertiliser, there are several brands available. Feed twice a year in early Spring and late Summer. Before applying citrus fertiliser, water the soil well under the canopy. Apply at the rate of 60gms per square metre of soil surface. For young trees, fertilise within the drip line area and water in thoroughly. As your tree matures, increase the rate annually by 500gms. Trees around six years and older should receive approximately three kilograms of citrus food each year. Do not cultivate under the tree as their fine feeder roots are just under the surface and they will be damaged.
A light pruning of your young citrus tree before planting will help encourage growth. Remove about half the top growth by cutting straight across the top. You may find that your Mitre I0 store has already done this job for you. Citrus as a general rule tend to be self-shaping and do not require much pruning. However, some varieties may benefit from some thinning out. Lemon trees once too large can be cut back to make them more compact. Remove any sucker growth and shots that emerge from below the graft (bud union). These are easily identified as they generally have a different foliage and often have large thorns.