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Citrus Cultivation

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 to be eaten fresh, squeezed for juice or made into tangy marmalade and other delicious food and drinks.

Many members of the MGS have become experts in citrus growing over the years and have offered their experience for all to share in articles printed below. For anyone interested in rare varieties Christoph Wieschus's article from back in 1999 is reprinted.
And since gardeners are nearly always interested in food there are a few recipes too.

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
See also: Growing healthy fruit in Spain, by Clodagh & Dick Handscombe, Santana Books, 2009  ISBN: 978-84-89954-62-5

A Collection of Rare or Hardy Citrus Cultivars
by Christoph Wieschus
From The Mediterranean Garden No 18 Autumn 1999

Oh! My Marmalade
By Mary Wilbur
From The Mediterranean Garden No 48 October 2007
The author describes the difficulties she has had finding 'sour' oranges in the US to make marmalade.
Here is her recipe.

Lemons, Lemons…and… More Lemons
by Helene Pizzi
From The Mediterranean Garden No 10 Autumn 1997
The author shares her delight in the lemon tree and its fruits.
How to make the liqueur limoncello and pasta with lemon sauce.

Citrus in California
California has areas of intense citrus cultivation, but amateur gardeners are also keen growers and naturally there is a wealth of information available and our Branch Head in North California has suggested these links.
Bracey Tiede writes: “I would recommend the 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. 

Another citrus source is Four Winds Growers, 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. The family is generous with speakers and answering questions online.”

Bracey also suggests a link to the Pacific Horticulture Society's magazine on-line for interesting varieties: Seizing Citrus Season and another with a little history: Orchard Trees of Rancho Los Cerritos: Lemon, Lime & Mandarin .

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.

This article is based on the pooled information of two such farms: Ca'n Frontera (Birger and Peta Jensen) and Ses Brises (Jaime and Sacha Ruiz) whose owners are members of the MGS, and amateurs in citrus-growing.  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.

When the Jensens bought Ca'n Frontera in 1986 there were nearly 300 citrus trees on their 8,000 square metres of land. About 30 were removed to allow for the construction of terraces, a garden and a pool. Since then citrus trees that succumbed to old age or disease have been replaced by four avocados, three peaches, one apricot and new citrus trees. The 260 remaining are:

  • 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


Valencia late


Peret

There was no Seville orange tree, so the Jensens planted one for marmalade. But the bitter oranges growing on the occasional branch of the original Mallorcan stock on to which other citrus types were grafted can also be used for marmalade.

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.


Peret orange tree

Photographs by Jaime Ruiz

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

Country/region

Cultivars/species grown

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.

A Collection of Rare or Hardy Citrus Cultivars

by Christoph Wieschus

Citrus species have been cultivated and hybridised for thousands of years, with the result that no one has been able to locate their natural place of origin with any certainty. The most probable area seems to be warm-temperate and subtropical Asia. The fruit is a berry-like hesperidium whose rind is dotted with glands that release ethereal oils, which may also reveal the type of tree when you crush its leaves. Another way of distinguishing citrus species is the size of the foliage and the wings along the stalk. Hybrids inherit such characteristics and thus often reveal their parentage by the appearance of their leaves.

In Western countries the genus has been divided into 16 species by W. T. Swingle, while the Asian classification of T. Tanaka lists as many as 157 species. Two hundred different cultivars were described by Battista Ferrari in 1646, and more than 3,000 types have been recorded in the following centuries. However, nowadays the choice is once again as limited as in the days of Ferrari since selection does not only mean improvement but also reduction of the number of varieties. The universities of Bologna, Naples and Palermo are now working in co-operation with the Blumeninsel Mainau (Lake Constance) to gather the relics of the age of orangeries.

Mainau Citrus Cultivars (rare varieties mostly with old cultivar names)

Citrus aurantiifolia ME

Citrus limon 'Neapolitanum'

Citrus aurantium ssp. bergamia

Citrus limon 'Perettone Canaliculata'

Citrus aurantium 'Bizzarria'

Citrus limon CA/10

Citrus aurantium 'Consolei'

Citrus limon CA/184/420

Citrus aurantium 'Corniculata'

Citrus limon CA/279

Citrus aurantium 'Crispifolia'

Citrus limon CA/375/7

Citrus aurantium 'Dulcis'

Citrus limon CA/56

Citrus aurantium 'Fasciata'

Citrus limon CA/67

Citrus aurantium 'Foetifera'

Citrus limon ´ medica 'Rugosa'

Citrus aurantium 'Horridus'

Citrus limon ´ medica CA/439/26

Citrus aurantium 'Listata'

Citrus medica 'Tuberosa'

Citrus aurantium 'Mutabilis'

Citrus microcitrus CA/387

Citrus aurantium 'Myrtifolia'

Citrus reticulate

Citrus aurantium 'Salicifolia'

Citrus reticulata 'Aurantifolia Da Semi'

Citrus aurantium 'Virgatum'

Citrus sinensis 'Comune'

Citrus aurantium 'Volkameriana'

Citrus sinensis 'Limetta Forma Diversa'

Citrus grandis 'Conifero'

Citrus sinensis 'Limetta'

Citrus grandis 'Maxima'

Citrus sinensis 'Oblonga'

Citrus grandis 'Pyriformis'

Citrus sinensis 'Pyriformis'

Citrus hystrix PA/98

Citrus sinensis 'Sigillata Forma Macrocarpa'

Citrus limon 'Bimammillata'

Citrus sinensis ´ limon 'Canaliculatum'

Citrus limon 'Cajetanum'

Citrus ´ paradisi CA/152

Citrus limon 'Canaliculatum'

Citrus ´ paradisi CA/443

Citrus limon 'Dulcis'

Citrus ´ paradisi CA/454/64

Citrus limon 'Duplex'

Citrus ´ paradisi ´ Nr.1

Citrus limon 'Foliis Variegatis'

Citrus CA/448/1

Citrus limon 'Inganna Villano'

 

This collection was started just a few years ago, with its focus mainly on Italy. The Sicilian nurseryman Dr. Messinas propagated many cultivars found in private gardens or in tiny nurseries run by part-time gardeners. In Malta the range of cultivars grown in nurseries is reduced to a few common types. If you are looking for treasures such as the Sweet Lemon (Citrus limon 'Dulcis') you would do better to ask a local farmer to supply some budwood for grafting. I assume that this situation is nothing new to most readers, and I hope that the above list will be of some a help in finding a specific citrus tree you might have been looking for.

Most varieties of citrus tree are grown for their delicious fruit but there are many others which produce ornamental fruit that may decorate the tree or the table. The bitter orange 'Corniculata', for instance, is one such eye-catcher with segments that do not all combine in a rounded fruit but sometimes grow attached as a horn. Grooved rind like a melon covers the fruit of 'Consolei'. The Swiss Guards of the Vatican wear trousers that resemble the cultivar 'Fasciata', while variegated foliage, grooved rind and green lines along the fruit make 'Listata' a very curious attraction; Citrus limon 'Fol. et Fruct. Variegatis' also has variegated rind together with green and white leaves. One of the most common oranges, the cultivar 'Washington Navel', grows a tiny fruit at the inner bottom of the large one, and such a double or ”pregnant” fruit is grown by the bitter orange 'Foetifera'. The ethereal oil of the bergamot (Citrus aurantium ssp. bergamia) is used to create perfumes or to flavour Earl Grey tea. Citrus grandis 'Maxima' grows “Jamboas” 15cm/6in in diameter with a tender taste which resembles that of the related grapefruit. The shrivelled lime of Citrus hystrix has been used by goldsmiths to clean jewellery. It has also been added to the water in which clothes are washed – in order to perfume rather than to clean.

Nowadays breeders try to produce plants that withstand pests, diseases and even frost. The hardiest citrus-like trees are Eremocitrus glauca (-8°C), Fortunella spp. (-8°C), Poncirus trifoliata (-25°C), Citrus ichangensis (-12°C) and Citrus reticulata ssp. unshiu (Satsuma, -6°C).

Hardy Citrus Cultivars

Edible Fruit:

'Segentrange Curafora' (-10°C, fruit sweet, thin rind, easy to peel, few or no seeds, evergreen, F2-parents: (Poncirus trifoliata x Citrus sinensis) Cultivar 'Sanford' x C. reticulata ?)

'Segentrange Hybrid 119' (-12°C, fruit sweet, juicy, 7cm/3” diameter, early, evergreen, F2-parents: (Poncirus trifoliata x Citrus ´ paradisi 'Duncan') x Citrus sinensis 'Succory')

'Segentrange Thomasville' (-10°C, fruit sweet, juicy, egg-shape and -size, evergreen, F2-parents: (Poncirus trifoliata x Citrus sinensis) Cultivar 'Willits' x Fortunella margarita 'Oval')

(Segentrange = Second Generation Citrange)

Fruit for Lemonade (resembling a Lemon):

Citrus ´ wilsonii 'Ichang Lemon' (-10°C, fruit sour, juicy, scented, 10cm/4” diameter, yellow, thick rind, many seeds, evergreen, F1-parents: Citrus maxima ´ Citrus ichangensis)

Fruit for Marmalade:

'Citrandarin' (-18°C, shrub, trifoliate leaves, semi-deciduous, fruit juicy, round, bitter, sour, early, thin rind, F1-parents: Poncirus trifoliata 'English Large' x Citrus reticulata 'Changsha')

Decorative Fruit:

'Citrange Rusk' (F1-parents: Poncirus trifoliata x Citrus sinensis 'Ruby')

'Citromelo Swingle' (F1-parents: Poncirus trifoliata x Citrus ´ paradisi)

'Citradia Brownell' (F1-parents: Poncirus trifoliata x Citrus aurantium)

Understock:

'Troyer Citrange' (F1-parents Poncirus trifoliata x Citrus sinensis)

'Swingle Citromelo' (F1-parents Poncirus trifoliata x Citrus ´ paradisi)

Unless you do not give supplementary watering, budding should be done in early autumn, whereas irrigated shrubs do best when grafted in early summer. Usually it is recommended to prune shrubs and trees before or after dormancy. However, when flowers overlap with the previous year's crop it is difficult to define the time of rest. In the Mediterranean climate late spring is the season to thin out citrus, bearing in mind that they do not like much trimming. Blooming can also be forced by some cold or carefully applied drought. Dropped foliage is not replaced by latent buds. Raising the pH to above 6.5 is usually indicated by chlorosis; iron chelate is an essential nutrient for citrus planted in lime. If grown in pots citrus require lots of humus (compost rather than peat) and should not be relocated without marking and maintaining the plant's alignment to the sun. Citrus rind decomposes easily when no chemical pesticides have been applied although the rind of citrus fruit bought in the supermarket will not be humified but will rot and reduce the number of organisms in your compost heap.

Oh! My Marmalade

by Mary Wilbur

Seville orange marmalade

8 medium bitter oranges
2 lemons
8 cups water
sugar to taste (6 to 8 cups)

Cut oranges and lemons in half, remove seeds and squeeze juice into a large bowl. Put seeds in a small bowl and cover completely with cold water. Slice oranges and lemons (thin or thicker, according to taste) and add to juice in large bowl. Cover with the 8 cups of water. Let both bowls stand, covered, for 24 hours.

Transfer contents of large bowl to preserving pan. Pour contents of small bowl through a sieve, mashing the seeds to extract the pectin. Discard the seeds and add the gelatinous remains to the pan. (Alternatively, pour the seeds and liquid into a bag of cheesecloth and add to the preserving pan.)

Simmer mixture gently for about one hour, until the peel is soft and the contents of the pan are reduced. Add the sugar to the pulp and bring to a boil, stirring until sugar dissolves. Boil rapidly for about 45 minutes or until two drops form on the edge of a spoon and drop off simultaneously. For a stiffer marmalade, continue cooking until the drops run together as they fall off the spoon. Pour into sterilized jars and seal.


Lemons, Lemons … and … More Lemons

by Helene Pizzi

Two recipes from the article

Limoncello

First of all, this delicious lemon after-dinner liqueur has been sipped on the island of Ischia for a long time, but only in the last decade has limoncello suddenly become a fashionable ‘must’ all over Italy. The fragrant liqueur should be kept in the freezer, like vodka, and served in tiny chilled glasses. For several years I tried to get the locals to share their fatto in casa recipe, but no one would give out their family secrets. Finally Rosalba Andriotti, who yearly makes a trip to Sorrento just to get huge unsprayed lemons for her liqueur, kindly agreed to share her ‘secret’ recipe… which is surprisingly so very simple to make.

Peel just the yellow rind of 1 kilo of lemons (the white pith is bitter). Place the rinds in a glass bowl together with 1 litre of pure 95% proof alcohol. Cover and set in a dark cupboard for 10 days. Boil 750gm sugar with 750gm water to make a syrup and cool completely. Pour the syrup into the alcohol and rinds. Stir well, then strain through a sieve and pour into pretty bottles (the bottles are important; choose interesting ones). Serve iced.

Elena’s Pasta all’ Limone

This very quick pasta dish is as delicious as it is easy to prepare. Put a large pot of water on the stove, and while you wait for the water to boil, prepare the sauce.

In a large serving bowl place the juice of 1 lemon, ¼ teaspoon freshly grated nutmeg, ½ teaspoon freshly ground black pepper, 2 tablespoons vegetable oil, 2 tablespoons butter and 50gm (about a teacup full) of freshly grated Parmesan cheese. When the water comes to the boil, salt to taste and cook 500gm (1lb) spaghetti (or short macaroni, or shell-shaped pasta), tucking the pasta under the water with a wooden fork and then giving it a good stir to separate the strands while cooking. Just before the pasta is cooked, add 2 spoons of the pasta water to the sauce. When the spaghetti is al dente, quickly drain in a colander, pour into the serving bowl and toss well. Serve hot, with extra Parmesan and black pepper, with a bottle of chilled white wine.

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