Citrus Cultivation

The photograph at the top of this page shows lemon in fruit and flower at the same time (Photo Wiki Commons)

Citrus growing is a subject which interests nearly everyone who gardens in mediterranean-climate areas. Old gardens in town and country will almost certainly have at least one lemon tree and probably a Seville orange tree as well, while those of us planting new gardens will want to try out some of the many interesting citrus varieties. What could be more appealing – compact trees with bright green leaves all year round and wonderfully scented blossom, as well as fruit which can be harvested over a long season.
Many members of the MGS have become experts in citrus growing over the years and have offered their experience for all to share: two of their articles printed below.

Two Citrus Orchards in the Sóller Valley, Mallorca
by Peta & Birger Jensen and Jaime & Sacha Ruiz

Lemons In Mediterranean-Climate Gardens
by Dick Handscombe
From The Mediterranean Garden No 74 October 2013

Citrus in California 
California has areas of intense citrus cultivation and our Branch in North California has suggested these links:
University of California Integrated Pest Management pages on citrus. These pages address cultural tips, invasive pests (California centric) and other pests, disorders and diseases that affect citrus. Really for the citrus lover. Four Winds Growers, is a local legend in citrus. The Dillon family originated the Meyer Lemon, a cross between lemon and orange here in California that many people love. Their pages are full of excellent information about growing citrus in a mediterranean climate.

Citrus in Italy 
Oscar Tintori in the Arno valley east of Pisa has an astonishing range of different varieties of citrus. He also offers therapy for distressed citrus plants.

For additional reports and articles on this subject please check out the (non-responsive) MGS Archive.

Two Citrus Orchards in the Sóller Valley, Mallorca
by Peta & Birger Jensen, Jaime & Sacha Ruiz

In Mallorca there is a sunny, humid and fertile valley, between the Tramontana mountains and the sea, where traditionally orange trees are grown. Frosts are practically unknown here as the valley is well protected from all winds by the surrounding mountains. All these factors, together with its favourable soil (a mixture of clay and limestone), as well as a reasonable distance from the seashore, make it an ideal location for growing citrus trees. A century ago the fruit was exported from its port (Puerto de Sóller) to the south of France and, through many of the local families, strong commercial and cultural links were established between the two countries. The citrus orchards were small and worked by family members, some of whom were sent to handle their interests in France.

In recent years, many of the younger generation have preferred working in hotels or moving to the capital in Palma and some of the farms have passed into the hands of 'forasteros' and 'extranjeros' – i.e. those coming from mainland Spain or further afield.
Two such farms: Ca'n Frontera (Birger and Peta Jensen) and Ses Brises (Jaime and Sacha Ruiz) are owned by members of the MGS.  During the past fifteen years the Ruizes have set up a tropical fruit section at Ses Brises (3,000 square metres with 140 citrus trees), described in TMG 69 and 70.

The Jensens at Ca'n Frontera have 260 citrus trees:

• Mandarins - harvested from November
• Clementines - November
• Navel oranges - end of December/January
• Navelina - February
• Canoneta - March
• Navelate - April to June
• Valencia late - Summer
• Peret - Summer
• Lemons, Mallorcan - Winter & Spring
• Lemons, Murciana - Spring to the end of the year, but less fruit in winter
• Grapefruit – pink and white - December until March, but fruit will last on the tree until May
• Seville orange - February/March

Watering
The average annual rainfall in Sóller is 800 mm, occurring from October to April. Intensive watering is therefore necessary during the long dry season. During their first five years at Ca'n Frontera, the Jensens used the traditional method of watering basins and channels made with a pharaonic spade. These were filled with water once a fortnight, with back-breaking effort, from May until after the first rains in September/start October. Now a drip system waters every tree, except for some lemons, for three hours three times a week at night from May until rains start in October, depending on heat and lack of rain.

Fertiliser
Twice a year, in May/June and September/October (after the rains start), all trees get two or three kilos per tree (depending on the size of the tree) of a citrus fertiliser compound which is sprinkled about one metre from the trunk (it must not touch the trunk). This is a mixture of: nitrogen (20 per cent), phosphorus pentoxide (12.2 per cent), potassium oxide (10 per cent), magnesium oxide 2 per cent), and sulphur trioxide (10 per cent). In addition to this, occasionally when trees seem to need it (yellowing leaves or general weakening), they get an additional small amount of magnesium.

Pruning
Every three years, after the fruit has been picked, branches are thinned out to maintain the strength of the trees and to facilitate light and air entering at all places. This includes clearing out the tree's interior and suppressing strong vertical shoots. Pruning often requires the removal of some large branches. (The jury is out as to whether cut areas should be treated with sealant.)

Spraying
The trees are sprayed annually with agricultural paraffin oil. This is done on a dry day after the first rains at the end of August or in early September. There must have been sufficient rain to arouse the leaves from their summer moisture-retaining mode. 

Pests
Fly-traps are installed at the beginning of the dry season, strategically distributed around the orchard, to capture the fruit fly Ceratitis capitata.

Lemons in Mediterranean-Climate Gardens
by Dick Handscombe
From The Mediterranean Garden No 74 October 2013

For two millennia or more, many gardens around the Mediterranean have had one or more lemon trees for their perfume, their fruit and their evergreen architectural effect. With the colonisation of the Americas and Australia, the lemon – like the olive tree – spread worldwide to all the mediterranean-climate locations in which MGS has branches today. The lemon tree could well be the emblem of the Society.

Choosing which variety to plant
Decisions on which lemon trees to plant need to take the following into account:

• The microclimate of the garden in which they will be planted. Lemon trees are less frost-hardy than orange, mandarin and grapefruit trees.
• Whether they will be planted in the ground or in a container. There are cultivars suitable for both.
• Whether you wish for a large specimen tree as an architectural feature or to hide an eyesore, a short tree from which you can harvest all lemons without needing a stepladder, or an open or tight hedge of lemon trees. Each option will need different kinds of pruning.
• If you are an absentee gardener, the times of year that you plan to be in residence to take advantage of the lemon crops. There are cultivars that flower and fruit once or twice a year or perpetually. This too affects their pruning needs. If you plan to be resident most of the year or have friends who would enjoy crops in your absence, we would always suggest one of the perpetual varieties so that fresh, ripe ecologically-grown lemons can be enjoyed all the year round for their zest, juice and whole fruits, with the added benefit of the almost continuous aroma of lemon blossom.

Pruning
If you have wisely planted a young one- or two-year-old perpetually flowering and fruiting variety, the following pruning pattern is recommended.

• For the first two years just remove low-growing braches to enable a thickening trunk to develop; also remove any suckers from the root stock on to which the chosen variety has been grafted. Do not prune the young framework of upper branches unless a branch is broken.
• After two years chose the two to four strongest branches as the basic framework for a mature tree. Remove the other main branches by pruning cleanly with sharp secateurs or a sharpened wide chisel and wooden mallet.
• From the third year, when fruiting will probably start, prune as follows:
• Trim back fruited twigs to the first healthy leaf as soon as you have harvested the fruit.
• In early spring remove most in-growing growth to keep the centre of the tree open in order to let the sun's rays in and to prevent humidity building up and attracting mealy bugs, scale insects and sooty leaves.
• In spring and summer trim back the tallest and widest growing branches to develop the shape and size you want and to stimulate flowering side shoots. If there are three shoots at the end of branches, prune out the middle one.
• At any time of year prune off any growth seriously affected by the citrus leaf miner, which causes curling leaves with holes in them and the hardening of the wood of young branches. An occasional ecological neem oil spray will help control this pest; give a monthly spray if trees are infected. Mix in propolis and you will remove and control sooty leaf attacks.
• Also remove any fast-growing water shoots as they appear.
• If your tree is likely to be exposed to frosts do not feed in the autumn or prune during the winter.
• If you experience severe frost damage, cut back affected branches to unaffected sappy growth in the spring after the risk of frost is past. A nettle infusion spray or a commercial eco foliar feed will help the tree recover. At minus two degrees Celsius many leaves will be killed, at minus four degrees branches will be killed and fruit frozen and at minus five to ten degrees trees will be lost.
• If you have a large tree such as a 'Lisbon' variety, do the main pruning in the spring before or just after flowering. Also trim lemon hedges at this time. If you want a large tree, lemons can grow to ten metres high with a twenty-metre diameter. At this size we have seen annual crops of over a thousand kilos!

Stunting
Unfortunately in spite of having purchased an appropriate tree and started to prune it correctly, many owners see a stunting and even dying back of the lemon tree after a few years. The most common cause is that the tree was poorly planted, especially if the tree was in a tall narrow plastic sleeve container when purchased at a nursery. In many cases the roots in these sleeves are squashed together and start to intertwine with each other in the form of a corkscrew. If not separated and spread out when planted, within a few years the young roots entwine into a tight corkscrew which eventually strangles the tree. So if you plant a young tree do prepare a good planting hole and plant in friable soil enriched with composted manures rather than just sliding the roots and soil from the sleeve into a narrow planting hole and then feeding with granular chemical fertilisers. The latter not only encourage the growth of the corkscrew but irreversibly burn the smooth non-hairy surface of young roots.
With care from day one, there is no reason why lemon trees cannot grow into specimen trees that survive for many decades.

Some varieties of lemon trees by country / region

Greece - Eureka*, Lisbon, Interdonata, Polyfora
Italy - Femminello*, Genova, Monachello
Sicily - Interdonata, Eureka*
France - Santa Teresa, Villafranca, Eureka*
Morocco - the Beldi lemon,  the bergamot
Israel - Eureka*, Villafranca
Spain - Berna/Verna, Fino, Lisbon, Luna*, Cuatro Estaciones*, Eureka*
USA - Eureka*, Bearss, Lisbon, Villafranca
Australia - Eureka*, Lisbon, the Meyer lemon**

*Indicates the perpetual flowering/fruiting varieties 
** From China: good for containers but with a single annual crop 
Note: 'Eureka' was developed in California from Sicilian seed.
In addition to the above, there is also the citrus sometimes called Citrus medica var. sarcodactylus (although this name is uncertain) which we grow in a container as a novelty for its strange-shaped fruit, resembling a half-open clenched fist – hence its common name of Buddha's Hand, or Hand of Allah in Spain and Morocco. This variety is said to have arrived in Spain during the Moorish period.

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