Best Tips for Growing Blueberries in Acid Soil
The very name almost prompts you to burst into patriotic Rodgers and Hammerstein, for the blueberry is a plant that has truly wound its way into American folk culture.
It finds its greatest glory in blueberry pie, but it also makes a very worthwhile garden plant if you have room and patience. Patience is certainly needed, because it will be at least two years before the plants begin to crop and five or more before they are in full bearing. The fruits do genuinely appear pale blue, because the waxy bloom lightens the dark blue-black skin colour. For those more used to seeing their wild European relative, the bilberry ( myrtillus), blueberries are large, 2cm (1in) or more in diameter and, although less than exciting when raw, they do cook wonderfully well. While you wait .for the bushes to come into full bearing, however, the beautiful yellows and reds of the autumn leaf colours will provide ample enjoyment and I have always felt that this is a plant worthy of a place in the ornamental shrub border in its own right.
It is, of course, thethat is the key to growing blueberries. It must be moist but well drained (and preferably, therefore, in a high rainfall area) and above all, acidic, with a pH of 4-5.5. The ideal is an acidic sandy loam; a garden where the soil is rather too acid to grow good vegetables will generally be a good blueberry prospect. Given a natural pH of up to about 6.5 and otherwise good conditions, it is worth adding sulphur to increase the acidity. Otherwise, they may be grown in large containers about 45 x 45 x 45cm (18 x 18 x 18in) of ericaceous compost.
Blueberries require a sunny position, with adequate shelter from strong and cold winds and also freedom from late frosts that will damage the blossom must be taken into account. The bushes themselves can be damaged by cold, penetrating winter frosts. As birds do not usually present a problem, blueberries need not be grown in a fruit cage or with any other special type of protection.
PLANTING AND SPACING
Blueberries should always be bought as container-grown plants for they do not transplant satisfactorily if bare-rooted. Two-year-old plants will establish best and should be planted in winter, in soil well supplied with organic matter, at a spacing of 1.2-1.5m (4-5ft) between plants and 1.5-1.8m (5-6ft) between rows. Don’t plant the bushes any deeper than the soil mark on the stem. Water thoroughly.
FEEDING AND WATERING
Blueberries must be mulched and this is best done with coniferous sawdust which breaks down slowly and increases the soil acidity as it does so. Somewhat ridiculous depths of mulch are sometimes suggested but 15cm (6in) is reasonable. They require little feeding: I7g per square metre (1/2oz per square yard) each of potassium sulphate and ammonium sulphate in the early spring. Maintain the soil in a moist state during dry periods.
More than almost any other soft fruit, blueberries resent root disturbance, so weeding between the bushes must be performed very carefully. The sawdust mulch should maintain the area close to the plants weed-free.
Blueberries are grown as stooled bushes and theiris identical to that applied to blackcurrants, the main principle being to stimulate the regular production of new shoots and growth from the base of the plant
Blueberries are slow to come into full bearing but after about six years, a bush should yield 2.5-3.5kg (6-8lb) of fruit. They should continue to crop for 20 years or more.
HARVESTING AND STORING
The cropping season is a long one, from late summer until early autumn but the fruit don’t ripen uniformly and the bushes must be picked over every few days. Place a hand under each cluster of berries and roll them in the palm. The ripe fruits detach easily. Blueberries will keep fresh for about three weeks in a refrigerator and freeze very well.
Blueberries are almost trouble-free. Leaf yellowing can occur if the soil pH rises but can be checked by applying a fertilizer containing sequestered iron in the spring. The only significant disease problem is a canker that appears as dark stem lesions with red and yellow margins. Affected parts should be cut out and destroyed. Botrytis grey mould may affect the fruits as they swell but can be checked by spraying with sulphur or a proprietary systemic fungicide.