Acid lovers and cane fruits- Blueberries, cranberries, lingonberries, currants

The majority of soft fruits love moist rich soil, preferably well mulched with leaf mould, and many are acid lovers actually disliking lime in the soil. Though some such as the currants thrive on almost any soils and can be grown almost anywhere others are more specific. Unless you really have moist acid soil conditions then you will need to grow the true Ericaceous fruits in containers. However if you do have lime free soil, and preferably a stream or pond, then these are the crops for you. Remember though that most prefer moist soils not water-logging (some cranberries are true bog plants. Though I don’t generally recommend popular music as a horticultural guide if you remember the song “Blueberry Hill” it rather indicates these grow on small knolls rising out of swamps not down in muddy waters.

We have native varieties, the Bilberry a.k.a Blaeberry, Whortleberry or Whinberry, Vaccinium myrtillus, is found on heaths and moors but is a poor choice compared to true Blueberries except for those wanting native species. Likewise there’s a native Cranberry, V. oxycoccus, which is distributed all round the northern hemisphere. But as with Blueberries the American Cranberry, V. macrocarpon, has proved far more popular, and considerably more productive. We also have the Cowberry, V. vitis-idaea, sometimes used as ground cover in moist acid shade for which it’s eminently suitable though the fruits are sparse and not as palatable as others of this large genus. The Bog Whortleberry, V. uligihosum, is another native, rare with black bloom covered sweet berries that are edible but said to cause giddiness and headache if eaten in quantity. Indeed there are dozens of other Vacciniums, most with edible berries, if you wished to start a collection or to hybridise. This includes more tender but still surprisingly hardy such as the Mortinia, V. floribundum, from Ecuador, but which has long been grown in southern parts of the British Isles for it’s racemes of dense rose pink flowers more than for it’s edible red berries. And from the Himalayas, so surprisingly only just hardy, comes the choice V. nummularia, best grown in alpine houses it’s dwarf, neat, attractive with rose red flowers in dense clusters on the ends of the shoots and followed by black edible berries.

However for the majority of kitchen gardeners the American Blueberry is the premier choice- though confusingly even this in fact belongs to three, or more, different groups of species, all of which are similar but varying in height and treatment. This is further confused by interbreeding so many modern cultivars have mixed blood. And few suppliers tell you the species only the trade name- though the strains can often be distinguished by their height.

Blueberries are commonly Highbush, but sometimes Low-bush or Rabbit-eye. The highbush cultivars are derived from V. corymbosum and V. australe. They are the most widely cultivated as their berries are large, black and very sweet and tasty much resembling seedless grapes a tad more pasty than syrupy. Their foliage turns fantastic shades of scarlet in autumn and make these good value as ornamentals even if you didn’t want their berries. They make moderately large shrubs in natural conditions though tending towards a thicket of vertical stems. The berries conveniently do not ripen all at once but continue to mature over many weeks. Of course these need bird protection but otherwise there are remarkably few problems, even dryish periods do not cause total failure but merely reduce production and growth. Highbush blueberries are most in need of pruning as they can over-crop resulting in large numbers of inferior berries. Over harsh pruning results in much fewer but bigger and earlier berries so is practiced commercially but for home use lighter pruning is better ensuring even cropping. Remove old and twiggy growths, any lax branches that might be pulled down by a crop and muddy it, and thin the remainder- even removing some strong vertical shoots if there are too many. Leaving bushes totally un-pruned gives bigger crops initially with poorer ones after so regular light thinning is recommended.

The Rabbit-eye varieties, V. virgatum and V. ashei, are mostly from the more southern US states so less commonly grown here. They can grow even taller than highbush, indeed too tall to pick so some shortening may be necessary of the strongest stems. Other than this, they grow less congested than High-bush, so pruning should be light just removing the oldest and weakest growths.

The Lowbush varieties, V. angustifolium, V. lamarckii and V. myrtilloides, are from the northern states and well suited to the UK climate. However apart from Top Hat and Blue Pearl which I believe may be Low bush most varieties offered are highbush. Uniquely where Lowbush blueberries are grown on a commercial scale they are ‘pruned’ by burning every three years or so rather than by hand cutting. Hay or straw is loosely packed around the bushes when the ground is sodden wet or frozen and the top growth burnt off, either in autumn or spring. The plants respond with strong re-growth free of pests and diseases, give huge crops the second and third year after burning, then the cycle is repeated. Fortunately you can hand prune instead treating these much like blackcurrants. So either cut them completely to the ground every third or fourth year or remove about a third of the oldest branches each year.

All Blueberry varieties need a moist acid soil and Ericaceous compost in big containers, a mixture of lime free garden compost and leaf mould works well with mine. The commonest, usually highbush varieties, really need a large planting tub apiece, though I find I can just squeeze three in an old bath they would be happier with a bath each. They can also be grown in suitably filled punctured, plastic lined pits (and redundant ornamental pools rendered safe - I converted mine when my twins arrived). Obviously you need to water with rain not tap water if you live in a limey area, regular feeding is not needed though every few years give a top dressing of leaf mould, compost and/or well rotted manure.

The Cranberry is a real bog plant, a mat forming spreader and can be grown in much wetter conditions than blueberries. They don’t need drainage more a moat. Indeed they are flooded commercially to float off the berries for collection and for frost protection in very cold regions. Large relatively shallow tubs are best as this is a runnering prostrate shrublet which flowers and fruits on short vertical shoots. For economy I grow them in the same containers with blueberries. The Cranberry crops on short vertical shoots and as with raspberries if these become too congested the quality suffers. Commercially they’re mown so simply shear back the most crowded portions every few years to renew their vigour and get better fruits.

The Lingonberry, V. vitis-idaea, is similar to our native Cowberry, but an improved Nordic form. Both resemble box hedging and bear cranberry type fruits. The Lingonberry should be popular as it’s relatively drought tolerant and a fair cropper. The berries need to be frosted for the best flavour which requires serious long term bird protection.

The Dwarf Lingonberry though is yet another American form also known as the Mountain Cranberry. There are even more Vacciniums known as Huckleberries such as V. Parvifolium and V. membranaceum, (these are better than the Solanum species sold us). Then there are the true Huckleberries, Gaylussacia species which you could grow, or even several Arctostaphylos species which are very similar in every way.

Indeed there’s a host of acid loving plants that bear edible fruits yet most are grown only for their ornamental value. Arbutus unedo, the Strawberry tree frequently bears edible fruits but luscious they’re not and it probably needs crossing with say the Madrona the Californian species A. menziesii. The Amelanchiers are grown for their shows of white flowers giving them the common name of Snowy Mespilus, though June Berry is more appropriate for A. canadensis as the berries can be sweet and quite tasty (better when dried) but there are no improved forms. Again it may be worth crossing with the most lime tolerant species, A. alnifolia which also has sweet edible berries.

Our common Blackcurrants though not strictly acid lovers as the above are happy in such conditions and love peaty and leaf mould rich wet soils. Blackcurrants will still crop in shade and take exceedingly wet conditions as with bog plants around the sides of ponds. The flavour is then ranker compared to those grown in drier sites though. Blackcurrants are well known for their high vitamin c levels and only became popular when sugar was cheap enough to sweeten their strong flavour. (If you want to see how strong it is look at the label to see the tiny amount of juice included in any commercial blackcurrant cordial- and that’s why home made does not taste the same; it’s invariably made too concentrated.) Anyway blackcurrants are much underrated. Do get new virus free varieties, feed heavily with compost or well rotted manure and prune hard. Prune one third of each bush away every third year. View it like a pie or cake then prune out a fat one third slice removing all shoots right down to a bud or less at ground level.

And the Red & White currants should not be overlooked. So reliable and easy anywhere, even on acid soils, but they are often over-looked. Yet their fruits are just as good as cranberries, especially if they are let hang until late autumn when they’re much the better. And unlike the others above these can be trained to almost any shape you wish as bush, cordon, espalier or whatever. But you know we really could do with a bigger sweeter form, it’s sad nobody has yet crossed these with gooseberries for example.