THE CULTIVATION OF CITRUS FRUIT - (Back)

Reads Nursery are the National Collection Holders of Citrus, Figs and Grapevines for the National Council for the Conservation of Plants and Gardens NCCPG.

"Home grown oranges, produced in light, airy, well heated and properly managed structures are much superior in flavour to imported fruit"

This statement by Horace Wright in his 'Fruit Growers Guide' is as true now as it was seventy years ago and is encouragement enough to grow the 'Golden Apple' of mythology and its many relatives, and obtain quite delicious crops. Citrus plants may fruit within a year of grafting but crops must be thinned to take account of tree si/c throughout its life. After a few years varieties such as Mover's lemon are in continuous production if grown correctly. British growers and gardeners have always been in the forefront of plant breeding and innovation and even with oranges - it needed the famous Rivers of Sawbridgeworth. Nurserymen for over 250 years, to show the Californian fruit growers of the 1870's which varielies suited their climate. Many of the varieties in our collection were rescued from Rivers when the Nursery- finally closed in 1982.

Citrus fruit may be produced in conservatories and greenhouses in this country providing the trees have adequate heal during the winter, the minimum temperature to aim for being 45F.(7C.) by night and somewhat higher by day. Higher temperatures are acceptable of course, but citrus dislike extremes and cannot tolerate being too hot in summer.then some form of light shade is beneficial to avoid scorching the young foliage. They do need well lit situations and are not suitable as houseplants,

COMPOST AND PLANTING

For a soil based compost use an equal mixture (by volume) of free draining loam, sharp sand peal and leaf-mould (or John Innes No. 2. but No 3 for large pots). A successful compost can be made with proprietary brands of normal potting compost with the addition of 20% by volume of sharp (gritty) sand A free draining medium is essential. Only use John Innes composts if you know the rootstock is lime tolerant.. Otherwise use lime free loam and a low NPK base fertiliser with trace elements When planted in a greenhouse border citrus can be rather vigorous and may require hard pruning from time to time. With roots confined to pots or tubs they are more easily managed in this respect and have the advantage that they are moveable and can be stood in a sheltered spot outside from mid July to early September. Citrus dislike being over-potted and we advise that repotting (back into the same pot) or potting on (into a larger pot) should be done in the late Spring. Pot size is increased by about 3" a time and a large plant (6ft - 8ft high) can be contained in a 20" or 24" tub almost indefinitely by top dressing each Spring. Every 2-3 years the plant must be removed from the tub, some 1 "-2" of soil removed all round, replaced in the tub and new soil tamped around the plant and well watered in.

WATERING

Newly potted trees require more frequent watering until they are established. If new growth wilts or leaves are dull you are waiting too long to water. Excessive leaf drop a few days after a good watering means that the tree became too dry before it was watered. In future be consistent, do not let the tree dry out Watering must take account of the plant's changing needs during the season. Citrus must never be allowed to become dry or continuously wet and to ensure this always water well (fill the pot) this may be daily in a hot summer but once a fortnight in winter. As a rough guide, one inch (2.5cm) of water on a pot will soak down six indies (15cm) in a soil based compost (See FEEDING.) In summer the foliage should be sprayed daily with soft rain water if available. (Water from water softeners is not acceptable to plants) This maintains healthy foliage & helps to ward off red spider mites and other pests.
Conservatory plants need a moist atmosphere that is relative to the temperature. Dry heat can cause leaf drop and twig die-back Capillary pebble trays part filled with water with pots standing on top and above water level - or room humidifiers will increase humidity considerably. During the Spring through to Autumn there is a natural day - night temperature difference in the conservatory. This should be maintained through the winter if possible and the day temperature should be 10F(3C) higher than the night one. This makes citrus fruits attain full colour and benefits many other plants bom flowering and fruiting.

VENTILATION

This is of paramount importance for all conservatory plants and if your conservatory has no roof vents consider the installation of an extractor fan that will keep the maximum temperature down to low 90F. Look at a Victorian built conservatory and you will see lots of opening lights in the roof and walls. If you are about to build a new one insist of roof ventilation (go to a manufacturer who offers them). Like an extractor fan they can be linked to a thermostat and will keep the temperature within reason whilst you are away. (See our catalogue for diagram) Condensation is caused by poor ventilation-tout is easily remedied with a controlled system of air movement in winter and summer.

FEEDING

Once the plant starts into active growth in the spring feeding may begin. If newly re-potted, leave a six week gap before feeding starts. Use any good general purpose fertiliser that contains trace elements (see notes on page 4) Nitrogen is the main requirement in spring and summer. Always use as directed. Yellowish foliage is usually a sign of lack of fertiliser or poor drainage. Foliar feeds may also be used fortnightly March - October when the new leaves are around half grown and onwards. The frequency of pot feeding will vary according to temperature, perhaps fortnightly in spring and autumn and weekly n high summer. At winter temperatures below 55F citrus stop growing and so should feeding - but above S5F continue through the winter.

PRUNING

Citrus are best grown in a rounded head form, either as bushes or standards or various heights. They may also be fan trained against a wall when planted in the greenhouse border. Pruning consists of pinching back branches which grow too strongly in summer, and the occasional removal or overcrowded branches in February/March. Hard pruning of old plants is sometimes necessary and can be quite severe with beneficial results. This will appear to mean the loss of flower buds, but citrus are very adaptable and the resultant new growth will flower within a few weeks. Strong short jointed wood is required to support the considerable weight of citrus fruits. This must also be borne in mind when thinning fruit, for most varieties will set tar too many. Clusters should be thinned to one fruit each on young plants to avoid branch damage through excess weight and overtaxing the plants. A young tree will grow much quicker without fruit for the first year
or two, a sacrifice that will be well rewarded in following years. Occasionally shoots will come from below the graft union, these will have a different leaf form and should be removed.

PESTS AND DISEASES

The main pests are:

SCALE, APHIDS & RED SPIDER MITES.

Scale insects start on the back of the leaf and can build up to smother the branches. After sucking sap from the leaves they excrete a sugary substance which encourages a black sooty mould on the leaf surfaces. Treatment with an insecticide is effective, only one spray being necessary if the trouble is seen early, but about three at fortnightly intervals clearing a quite bad attack This will also clear greenfly. As an alternative control leaves may be washed with soft soapy water, though this is most effective when the pest is at a young and vulnerable stage, regular inspection is important The sooty mould can only be removed by washing.
Red spider can also be troublesome, in the early stages it appears as small peppery spots on the underside of the leaves. The mites are mostly pale fawn with Mack spots. Soft soapy water can control them, but if insecticides are used the basic formulae must be varied to avoid a build up of resistance.
Red spider predators are now widely available and are very effective if used in the early stages. Predators are unfortunately less active at temperatures under 50F and prolonged periods below this in late spring or summer may allow red spider to gain a foothold. In this case a back up spray can be used to control them, but this must be of the type that is not harmful to the predator. We now use predators extensively.
We can be thankful that Britain does not number the beautiful Orange Dog butterfly amongst its species. The caterpillar is very partial to citrus and can eat a large leaf in a few minutes. In the standard 19th century book on citrus the treatment was to hand pick the eggs and caterpillars. As for the butterflies the recommendation was to shoot them!

Citrus Food. We have a specially formulated mix which reduces lime content in the water and contains all the nutrients and trace elements needed. As used by commercial growers, it provides a perfect balance for healthy plants.
Foliar spray 'Maxicrop'. Soft Soap 'Savona' (mix with rainwater)

Ccitrus fruits cover a wide range of types and flavours. –lemons, oranges, limes, grapefruit, limequat, tangelo, satsuma, Clementine, kumquat, calamondin, djeerook lime,kaffir limes and many others.

Their uses range from lemon , orange and grapefruit juices to culinary types such as the Kaffir limes used in traditional thai food. Lemons can flower many times a year ,holding small lemon fruits right through to full size lemons on the same tree. Blood oranges are particularly good as fresh fruit with a rich blood orange flavour.

Clementines and satsumas are best eaten fresh from the tree in winter and these satsumas will have a much tastier flavour than satsumas from the shops.Limes such as Tahiti Lime, are the choice for drinks and Tahiti will go well with the gin.Key limes crop prolifically and the sharp flavour of key lime makes a wonderful key lime pie. Tangelo fruits like Tangelo Ugli have distinctive shapes and Dweet Tangors ar best fro flavour.

SECTION of lean-to conservatory showing roof light, side light wall ventilator & slatted bench &. air flow direction. The roof light is opened first. In winter this may be enough, when father cooling is required open the side lights - orjust the wall ventilator (a small sliding panel) Avoid cool drafts at all time A slatted bench is shown for the display of small plants

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