Citrus trees include Lemons, Oranges, Tangerines, Limes, Grapefruit and Kumquats – In Britain these are best grown in pots and given protection from frost in winter.
Position & Growing Conditions
The secret to growing citrus trees is to aim for a constant regime as they resent extremes of temperature and moisture. Using open free-draining compost and terracotta pots are important factors to success.
In winter citrus trees can be grown in either a cool or warm regime.
Cool Growing Conditions
If citrus trees are almost dormant and making little if any growth, cool over-wintering conditions are best. With cool growing conditions plants need to be first acclimatized to the cold conditions and kept frost-free. Night time temperature of between 5 & 10C (40-50F) is ideal. Good light is essential so a sun room or conservatory is perfect. They should be kept as dry as possible without wilting, this avoids root rots.
Warm Growing Conditions
If you keep your citrus trees in a warm environment all winter, then 80-90% humidity is required. Avoid hot dry air and draughts, (this is often the cause of leaf fall but plants do recover). To maintain humidity stand your plants on a saucer filled with gravel with the water level just below the gravel surface.
Occasional misting over the leaves with rainwater will also help.
In summer they are much happier outside when all chance of frost is gone. [late May until end August]
Citrus trees prefer soft water; so use rainwater whenever possible.
Water when the surface of the compost has started to dry out but wilting has not started. Give them a good soak, then do not water again until they are dry.
Water regularly in summer but very sparingly in winter unless they are making new growth.
Compost & Feeding
Soil-based compost is the norm for home gardeners. Use a John Innes potting compost No.3 with 25% extra lime free grit added to keep the compost open and free draining. Alternatively, use a ready made Citrus compost which we sell. The ideal pH for citrus is around 6-6.5 (neutral).
Plants that do require re-potting should be potted one size up in spring. Do not over pot them as they do not have a vigorous root system! Just move into a pot with a diametre of 3-4 cms bigger than the root ball.
Those plants that are not re-potted can be top dressed with new compost including a slow or controlled release fertiliser. Osmocote granules can be incorporated into the potting compost and gives up to 6 months of steady fertilizer release.
Should the plant show any signs of nutrient deficiency then a top up with liquid feed.
Use a specific Citrus feed such as Maxicrop Citrus fertiliser. This contains a balanced ratio of all the elements essential for good plant health and growth.
Citrus do not require very much pruning. When pruning is required this is mostly carried out during the summer. It would consist of trimming back straggly and strong growing shoots to maintain shape and to avoid over crowding. This allows for good air movement aiding healthy plant growth.
Suckering can occur and tearing a shoot from the root rather than cutting them off should be practiced to avoid additional suckering from any cut stump left behind.
Pests / Bugs
Citrus trees can be attacked by aphids, red spider mites, mealy bug and scale insects.
Aphids can be controlled easily with an insecticide containing rape seed oil or a soap based insecticide.
Red Spider Mite, Mealy Bug and Scale insects are not so easy to control and should be treated early with either (but not both), an insecticide or biological controls from Agralan. SB Invigorator is worth trying to control these [and aphids] and is one of the safer insecticides available. – Ask in store for current recommended products. Low scale infestation of mealy bug and scale insects can be brushed off with cotton buds dipped in 50% surgical spirit and 50% water. Red Spider Mite can also be deterred by keeping humidity high.
Very few diseases attack citrus plants.
Sooty Mould can develop on the leaves and is an indicator of the presence of scale or aphid on the leaves above. To control eliminate the pest and wipe the mould off with moist cotton wool.
Canker can be very troublesome and if seen affected branches should be cut out taking care to sterilise tools to avoid spread.
Use Pesticide safely, always read the label.
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