If you follow some basic rules, growing citrus fruits in containers can be productive, ornamental and aromatic, writes Mark Abbott-Compton
One of the great things about growing citrus fruits is that you get both the fruit and flowers on the plant at the same time, and they will flower right through from spring to autumn for a really long and productive growing season. One of the other main reasons for growing citrus fruits is the absolutely beautiful scent, which is almost as wonderful to have over this extended period as the delicious fruit.
EASY… BUT TRICKY
Citrus fruits are not difficult to grow and are also remarkably tough and very resistant to neglect and abuse. That said, it can be quite tricky to keep them growing well. The plants can survive quite cold temperatures, but they will stop actively growing below 11.5°C, and at below 10°C lemons will shed their leaves, whilst kumquats will shed their leaves at below 5°C.
Perhaps somewhat surprisingly, citrus plants also dislike very high temperatures, and these, too, can lead to leaf yellowing and dropping. The plants will certainly benefit from spending summer outdoors on a deck, patio or in your garden from around the end of May until the end of September. The best way of doing this is to move them outside into the shade, then, over a period of ten days or so, gradually move them into full sun – once they are acclimatised, the more sun, the better.
LIGHT IS THE TRICK
The main requirement in winter is to provide them with as much light as possible, and if they are in a greenhouse, it must be kept frost free; this will suit citrus plants perfectly. The main reason for plants failing to flower in summer is a lack of light during the winter months.
Citrus plants can be kept in an unheated conservatory during the winter months, so long as they are away from draughts. They dislike fluctuating temperatures, which are actually more likely in heated conservatories due to the central heating being switched on and off, when temperatures can drop considerably, causing leaf-fall, together with buds dropping off and the plant possibly suffering later in the growing cycle from a lack of flowering.
Paradoxically, citrus plants don’t like a dry atmosphere, so I would recommend filling a waterproof saucer with horticultural pebbles, which you can then keep topped up with water whilst ensuring that it is kept separate from the pot while the pot actually stands on it – or rather above it – ensuring that the plant has a moist microclimate, which helps to keep it healthy.
Citrus plants will be quite happy in relatively small-sized pots or containers, and terracotta is the best option because there will be less temperature fluctuation around the roots, less chance of wet roots, and they do not get as hot as plastic pots. Traditionally, they were grown in square wooden tubs made of oak or chestnut, which could be moved in and out of an orangery with relative ease.
Don’t be tempted to ‘overpot’ your citrus plants – they are best moved up a couple of pot sizes at a time, and March is normally the best time to do this. It is also worth taking care with your compost, as it will need to be free draining. A great mix would be:
- 50% soil-based compost (such as John Innes No. 3),
- 25% leaf-mould
- 25% perlite or sand
They should really thrive with this mix, but if you don’t have any leaf-mould, then a 50:50 mix of John Innes and perlite also gives great results. They also need lime, so John Innes No. 3 is a very good choice, as it contains all of the essential trace elements the plants will require.
FEEDING LITTLE AND OFTEN
As an evergreen, a citrus plant stores most of its starch in its leaves, so the denser and leafier the plant, the more fruit it will produce. It therefore requires feeding, and responds best to a specialist citrus, high-nitrogen feed with an essential trace elements fertiliser specially balanced for good leaf canopy development. I feed my citrus plants with a weak feed on a weekly basis from April through to September.
DRY AND DRENCH
Citrus plants will benefit from being watered with tap water, as it supplies the plant with much-needed calcium.
Water at ambient temperature is always best, so leave your watering can full in the greenhouse. When it comes to actual watering, a good rule of thumb is to water every day during the heat of the summer, and possibly every fourteen days during winter. Let them become dry to the point of almost drying out, then give them a really good soaking, but as the commonest cause of their demise is overwatering during the cooler months, always err on the side of caution in autumn and winter – if in doubt, just don’t water!
CITRUS AS A SIGN OF WEALTH
One of the most famous collections of citrus plants can be found at the Palace of Versailles, where there are over 1,000 trees, some over 200 years old. Citrus trees have been growing there since 1686, and are grown in wooden ‘orange boxes’, which are moved outside for the summer, and by clever feeding and pruning they produce fruit all year round.
In Britain, orangeries can be found at Kew, Hanbury Hall in Worcestershire, Ickworth House in Suffolk, and at Margam Park, which at 100m is the longest one in Wales. Citrus plants, especially oranges, were so revered when first introduced that mediaeval cookbooks told exactly how many orange slices a visiting dignitary was entitled to consume. Today, the rind of ‘Fantastico Bergamot’, a variety of orange, produces oil that is used for aromatherapy and to perfume Earl Grey tea – contrary to what most people believe, it is this oil and not the herb bergamot, which is the source of its perfumed aroma.
PLANTS OR SEEDS
You can grow lemons from seeds. They will take 3–6 years to fruit, but you are unlikely ever to know the variety, so their value will be one principally of novelty. I would always recommend acquiring 2–3-year-old trees as a better investment than growing them from seed, as even if the variety is known you can still get a lot of variation when growing from seed, which is why a lot of commercial citrus is grafted. Varieties I would recommend are:
- ‘FOUR SEASONS’
This lemon is a good all round fruiter, which can flower several times a year, gives good scent and year-round fruit. It is great for that G&T at Christmas.
This is grown mainly in Spain, and about 70 per cent of all the lemons grown there are this variety. It can flower up to three times a year. The tree is of spreading habit, and a good beginner’s plant.
This orange produces small, sour, orange-like fruit, and is rarely without both fruit and flowers. It is wonderfully ornamental, and the fruit makes a great marmalade. It is ideal as a beginner’s plant on a windowsill, or in a greenhouse or conservatory.
This kumquat variety is normally found in supermarkets. Oval in shape, the fruit has a sweet skin and a sour flesh, and can be eaten whole or used in cooking.
Possesses leaves that are essential for many Thai recipes. Picked fresh off the plant, the leaves of this lime are many times more aromatic than the imported leaves. It is also not difficult to grow and will soon pay for itself.
Grown well, citrus plants suffer from very few problems. The main problem is root rotting due to overwatering, but they can also be attacked by pests such as scale insects, mealy bug and red spider mite. Visit http://www.learn-how-to-garden.com/scale-insect-and-sooty-mould-infestation to learn about the best way of tackling them.