How to Grow Cranberries in Acid Soil
I suppose the fact that cranberry sauce is so frequently served with turkey, explains why the plant has become so important in North America.
It is a pretty little thing, especially when in fruit, its wiry stems winding their way over thesurface and studded at regular intervals with bright red jewel-like berries, each slightly over 1 cm (½ in) in diameter.
It isn’t easy to grow in gardens, the key to success being to remember that its natural habitat is close to acidic bogs; and bogs mean water.
SOIL AND SITE
The soil should be as for blueberries but, if anything, even more acidic (as low as a pH of 3.5), organic and wetter but still free-draining. This necessitates either a high rainfall or a supply of soft water to supplement it. It’s worth bearing in mind that even if your garden soil is very acidic, you may still have hard (limey) tap water that is piped from an area of alkaline rocks so stored rainwater should be used. An ideal position for a cranberry bed would be in a bog garden on a peaty soil.
PLANTING AND AFTERCARE
As with blueberries, always buy container-grown young plants and never allow them to dry out. Plant in winter no deeper than the soil mark on the stem. Spreading a layer about 2cm (1in) deep of lime-free sand over the bed after planting will help the plants to establish and prevent the surface organic matter from drying out. The sand should also be used to hold down the trailing stems until they root. Space the plants 30cm (12in) each way and you should obtain a yield from an established bed of about 0.5kg per square metre (1 lb per square yard) .
Cranberries will grow well with no artificial feeding although 17g per square metre (1/2oz per square yard) of sulphate of ammonia should be given in early spring if growth in the previous season has been poor. Nois needed but any aerial shoots should be trimmed in spring.
HARVESTING AND STORING
Cranberries are extremely fiddly to pick so it is wise to wait until more or less all of the fruit have ripened, and then pick them in one session. Despite their fragile appearance, they keep very well — for two months or more in a refrigerator — and keep their shape if frozen.
Slight aphid infestation is the only pest and disease problem likely to be encountered on cranberries growing in Europe.
From limited trials in Scotland, the best cranberries for garden conditions have proved to be the American varieties, ‘C.N.’ with large red fruit and a free mat-forming habit, and ‘FRANKLIN’ with smaller, darker fruits and a less vigorous spread. Most specialist suppliers should have at least one of these, although you will have to make do with others if these are unavailable. ‘EARLY BLACK’ and the late season variety ‘McFARLIN’ are probably the best of the rest.