Citrus Varieties
Orange Citrus sinesis:Valencia Late (medium size, very juicy)
Orange Navel (large, thick skinned)
Lemon Citrus limon
Eureka Lemon (large, acidic juice, crops all year)
Meyer's Lemon (a lemon x orange cross, so sweeter juice)
Imperial Lemon (a lemon x grapefruit cross)
Tuscan Lemon (large glossy fruit)
Grapefruit Citrus paradisi
Star Ruby (pink flesh)
White Marsh (yellow flesh)
Lime Citrus aurantifolia /C.latifolia
Bears' Lime (large, seedless and sharp flavour)
Wikipedia has the Bears' lime as identical to Persian and Tahiti Lime.
Currently stocked at Dobies. £20 instore. £50 online
Sources of Plants:
Cross Common Nursery
(This company supplies young grafted starter plants)
Propagating Citrus
Citrus can be grown from seed, rooted from cuttings, layered, or grafted onto rootstocks.Seeds from fresh fruit are rinsed and sown 1-2cm. deep in free draining peat
compost with 25% perlite or vermiculite at 20 to 28oC. This is best done in the
early Spring. Germination takes a week or two depending on the temperature.
Some seeds are poly-embryonic and produce two or three seedlings. Cultivation
from seed is cheap but the plants are not guaranteed to share the parental
characteristics, and they could take 10 years or more to reach the fruiting stage.
Seed grown plants can however be used as rootstocks for grafting.
Stem cuttings from named varieties of citrus will root fairly easily in a
mixture of loam and vermiculite. Plants can also be propagated by layering,
either air layering or just pegging a low branch down into the soil or compost
in an adjacent pot. The plants will have the same fruit characteristics as the
parent but may not be as vigorous or productive as those grafted onto rootstocks
specially adapted for cultivation in the UK. Generally very cheap to buy.
Rootstocks are then used as the hosts for grafted buds or woody shoots from known
cultivars.
Grafting gives growers more control over factors such as the size of the trees, disease resistance and time to reach maturity.
Techniques of grafting are described here.
Ready grafted specimens of named varieties are the best way to start a citrus collection. Fruiting size plants will cost about £30-£50 but immature, grafted, starter plants are available for less than £10 from Cross Common Nursery in Cornwall.
Citrus generally will self pollinate, so only one plant is needed. Mandarin hybrids are an exception.
Planting and Aftercare
Citrus trees are adapted to a Mediterranean climate of hot summers averaging 27oC and mild winters rarely below 5oC. Protection from frost is therefore vital. Bearing in mind that they are expensive and long lived plants, it is very risky to plant them permanently outdoors in the UK, despite any suggestions to the contrary on the label.
Traditionally, citrus were raised in the specially designed orangeries attached
to larger country houses in Britain. This link gives a short history of
Orangeries
This is the magnificent orangery at Powis Castle with a row of citrus trees
just moved into position for the summer
Today citrus can be happily accommodated as evergreen pot grown plants,
overwintered in a conservatory or cool greenhouse at a minimum temperature
of 6 or 7oC. During the summer months they make sweetly scented and beautiful
patio plants. They normally require good sunlight, but in a greenhouse they
would need shading if the temperature goes above 30oC. Citrus tend to drop their
leaves if subject to sudden changes in temperature or light, so good ventilation
and circulating the air in the greenhouse all help.
Potting mixtures should be very light, well drained and slightly on the
acidic side. Citrus are shallow rooted so you can afford to put plenty of
crocks at the bottom of the pot. Mix equal volumes of peat based compost and
John Innes no 3. Then add 25% perlite or vermiculite to this mixture.
Careful watering is essential. The roots will quickly rot if the compost remains
soggy especially in winter when the plants are semi-dormant. In the summer, pots
can be watered whenever the compost dries, daily if necessary. A thorough
soaking until the water drains out the bottom is best. If you live in a hard
water area, use rainwater for the plants. Regular mist spraying with water
helps to regulate the temperature. Stand the pots on a water tray of pebbles,
and mist spray the leaves during hot weather.
In spring a high nitrogen fertiliser is useful to boost vegetative growth.
Later the more general fertiliser used for tomatoes can be applied once a week.
Watch out for iron deficiency where the leaves turn yellow but the veins stay green.
Plants flower and fruit continuously but the main mass of flowers opens in
early summer. They smell gorgeous. Bees will visit the blossom but, unusually,
in many varieties, fruit will set without pollination or fertililsation. This
parthenocarpy produces seedless fruit. Don't worry if most of the immature
fruits turn brown and drop off. The remaining ones will develop slowly,
taking up to 18 months to reach their full size and colour. Some support
may be necessary to prevent their weight breaking the thin branches.
Ripe fruit can be left on the plant for months without deteriorating.
In fact there is a theory that the ripe ones help to speed up the development
of the rest.
Pruning is minimal. Remove any thin leggy and leafless branches to preserve
a pleasing shape to the plant.
