Growing Citrus Trees

“What’s wrong with my lemon tree?” is the most asked question we get in our magazine. So we thought it was a good idea to go through the basics and then troubleshoot some common scenarios. We also have some exciting new citrus varieties available that we are sure you would be happy to have in your garden and kitchen.

What is citrus?

The dictionary (Oxford) version goes like this: “a tree of a genus that includes citron, lemon, lime, orange and grapefruit. Native to Asia, citrus trees are cultivated in warm countries for their fruit.”

The citrus varieties mentioned on the list above are all well-known and, with the exception of the citron, are available in South Africa. A citron is most often used just for the zest, has very little juice and is not grown much in South Africa

Types often referred to as ‘soft citrus’ are not mentioned in the dictionary version, but these are definitely citrus. Soft citrus includes ‘easy peelers’ like mandarins, clementines, satsumas, mineolas, tangerines and, of course, our very own naartjies. Kumquats can be added to the list as sour citrus and are usually used for making marmalades and jams. Calamondins are also citrus but are usually grown as ornamental trees, although the fruit is still edible.

Citrus Varieties

In South Africa, we are lucky to have a very good supply of citrus with these varieties being the most popular:

Lemons

Rough-skinned lemon – The Cape rough-skinned lemon is the oldest type of lemon found in South Africa. It was introduced from St Helena in 1654 by the Dutch East India Company. You will often find these lemon trees in older gardens.

‘Eureka’ – the most popular lemon in the world has smooth skin and is very juicy – all you want in a lemon. It also has fewer seeds.

‘Meyer’ – not a true lemon, as it’s a hybrid between a lemon and an orange or tangerine, but hardy and cold- and frost-resistant.

In South Africa, we also grow agriculturally ‘Lisbon’, ‘Limoneira’ and ‘Genoa’, which all do well in our climate.

Grapefruits

‘Star Ruby’ – developed in the 1970s, this variety has smooth yellow skin with deep red flesh, and it performs very well in our climate. It has a large fruit with few seeds.

‘Marsh’ – before the ruby-coloured grapefruit appeared on the market, the most popular was this variety, known for its large fruit for fresh eating and juicing. It is also seedless.

Oranges

‘Navel’ – named for its very cute second fruit that develops at the base of the fruit and resembles a human navel. These types are usually very juicy.

‘Valencia’ – named after the Spanish town, this is a very sweet orange with thin skin.

Limes

‘Bears’ – the most planted lime in South Africa with a thin skin and juicy flesh. The tree produces an abundant crop.

‘Tahiti’ – as the name suggests, it originates in the Tahitian Islands and is known for being juicy and seedless.

Soft Citrus

Mandarins and tangerines are technically the same, just originating from different regions – mandarins from China and tangerines from Tangiers in Morocco. The varieties planted in South Africa include ‘Nadorcott’, ‘Nova’ and ‘Tango’.

Clementines are considered an accidental hybrid or even a mutation of some mandarin varieties. Our local production is dominated by the Spanish variety ‘Nules’, with ‘Esbal’ following second.

Satsumas are what we call naartjies in South Africa, and most of what we grow locally is a variety called ‘Miho Wase’ from Japan. What is curious is that this variety was never as successful in Japan as it is in South Africa.

Something New

An exciting new development for citrus growers, and particularly foodies in South Africa, is the introduction of finger limes into the country by Heuers Wholesale Nursery. They will be available under the Heuers label countrywide.

This finger lime (Microcitrus australasica) is one of six of Australia’s native citrus plants. The fruit resembles fingers and has a dark greenish-black to purple skin. The juiciest pearls of citrus inside are also known as ‘citrus caviar’. They have a fresh lemon-lime flavour and can be used anywhere lemons or limes are used. They are especially good with seafood. The trees grow up to 5m tall and can have fruit all year, with the main crop in autumn and winter. Look out for them at your local nursery.

READ MORE: Learn about miniature citrus varieties in this article.

Growing citrus

When to plant

Most growers plant in spring so that the plant has enough time to get hardened before winter sets in for young trees. You can also plant in autumn in areas that are a bit warmer.

Choosing the site

All citrus trees prefer full sun to flower and set fruit, and that includes any planted in containers. A warm area protected from strong winds is best. Make sure the soil is well-draining as citrus do not do well in soil that is waterlogged or in clay soils. Their roots need a lot of oxygen to work properly. The best soil is rich loam which is more on the sandy side, with a good amount of compost added.

What Citrus trees need

Water – citrus trees need plenty of water, particularly when flowering and setting fruit in spring and summer. Note that lemons can flower and set fruit up to four times a year, so they need constant monitoring. A good way of watering deeply is to make a basin around the tree, flood it with water and then allow the water to soak into the soil.

Feeding – if young trees are planted in well-prepared soil, you won’t need to feed them much for the first couple of years. However, if the soil is poor, start the feeding schedule earlier. Citrus will require feeding at least four times a year in July, September, January and April to keep producing fruit. A balanced fertiliser like Atlantic Fruit & Flower, 3:1:5 or 8:1:5 will do for trees planted in the ground but feed container citrus more often using a water-soluble tonic that includes a handful of organic fertiliser, especially in spring and summer.

Pruning – where it is possible, you should not prune your citrus trees. But sometimes it will be necessary to open the canopy to allow more light into the centre of the tree. Remove any damaged branches and remove any growth that is below the grafted stem. This will prevent the rootstock variety taking hold.

Citrus Troubleshooting

These are the most common questions asked by readers about growing citrus trees, especially lemons.

Q. Why have I got ugly bumps on my lemon leaves?

A. A pest called citrus psylla is responsible for the unsightly bumps on the leaves of lemons. It is caused by the young psyllids when they hatch and start feeding. It will only be the leaves that are infected and not the fruit unless the infestation is severe. Ladybirds, wasps, lacewings and birds can help reduce infestations and control citrus psylla. Spraying can help but will also kill off the good insects. Psylla can also be controlled by using Oleum – by smothering the psylla – this method of control means that you can continue to harvest the fruit all year long.

Q. My tree doesn’t fruit. What could be wrong?

A. There may be a few reasons for a citrus tree to not fruit. It could fail to form flowers due to wind, cold or damage, a lack of nutrients, or insufficient water. It may also be the case that the tree is not yet old enough. Lemons, for example, will only start setting fruit after 3-5 years of growth. Any of the new hybrids will set fruit in the first year.

Q. My lemon has yellow leaves, what is wrong with it?

A. This is often caused by chlorosis, which is caused by a lack of nutrients. However, the most common problem resulting in chlorosis is overwatering. This essentially suffocates the roots, preventing them from taking up nutrients in the tree. Chlorosis is an iron deficiency and should be treated with chelated forms of iron as a soil drench.

Q. Can I grow citrus indoors?

A. The short answer is yes, you can grow citrus trees indoors. The longer answer says that there are a few conditions and you may not get the results you want. Most indoor trees are dwarf varieties or those that produce sour fruit. The sweeter-fruiting varieties need plenty of sun to develop the sugars in the fruit. Citrus indoors needs at least 6 hours of sunshine a day, and if that can’t be achieved with its position indoors, then you will need to invest in grow lights.

READ MORE: Learn more about pests that affect lemon trees in this article.