Preparing the Ground for Growing Soft Fruit
With two very significant exceptions, the preferredfor all types of soft fruit is similar and can be satisfied in most gardens. A well drained medium loam with a pH of around 6.5 (that is, one just on the acidic side of neutral) is ideal. In general, a soil that is slightly wetter than this will naturally produce better crops than one that is on the dry side, but both can be improved by digging in quantities of well rotted manure, compost or other organic matter.
A dry soil is, of course, a soil short of water and as it is water that causes soft fruit to be soft, those produced on drier sites tend to be small, hard and tasteless. On naturally heavier, wetter soils (which also tend to be colder), you are likely to achieve the best success with blackcurrants, followed by raspberries, blackberries and related hybrid berries; as much as anything because they are more tolerant of the root-rotting fungi that are prevalent in wet conditions.
Problems will occur with most soft fruit, and especially with raspberries and, when they are grown in a chalky soil. This is because the important element, iron, is difficult for plants to take up in alkaline conditions. Iron is needed in the manufacture of the green photosynthesis chemical, chlorophyll. Iron shortage causes chlorosis which is manifest as the development of pale coloured leaves with dark green veins. Because of the shortage of chlorophyll, the leaves and the plant as a whole fail to function properly. It’s very difficult to acidify a naturally chalky soil and when the pH is very high (above about 8.0), soft fruit growing will be particularly difficult. In only slightly alkaline conditions, however, it makes sense to apply sequestered iron once a year in spring. This is iron in an organic form that can more readily be taken up by plants from chalky conditions, and several specially formulated proprietary fertilizers provide this.
ACID SOIL FRUITS
The exceptional soft fruit to which I referred above are blueberries and cranberries. These are often grouped together, as I have done, under the name ‘acid soil fruits’; the term ‘heathland fruits’ is also sometimes used. The conditions they require are truly those of a natural peat-rich heathland; extreme acidity, with a pH as low as 4.0 or even 3.5. Unless your soil is naturally of this type, therefore, it is not worth trying to grow these plants, any more than it’s worth trying rhododendrons, azaleas and summer-flowering heathers.
I have said on many occasions that time and effort spent on improving your garden soil will never be regretted. But ‘improvement’ doesn’t mean the same thing to all gardeners so perhaps I should outline what can and should be done to soil and what can’t and shouldn’t be attempted. By and large, while soil structure can be changed, soil texture cannot. For texture is an expression of the relative amounts of sand, silt and clay particles that the soil contains. You can add many tons of sand to your garden soil but it will be, to use a familiar metaphor, just a drop in the ocean. Soil structure however expresses the manner in which these particles are associated with organic matter or humus to produce a blend of larger, pellet-like crumbs with holes or pores between. And by adding organic matter, you can certainly increase both the number of pores and crumbs, a process that paradoxically will increase the moisture retentiveness of a free-draining sandy soil just as readily as it will improve theof a heavy clay.
Organic matter can be added to soil as a surface mulch, a beneficial enough process in itself that cuts down water loss through evaporation and suppresses weed growth. In due course, worms will drag down the surface mulch into the body of the soil. But as a method of adding large quantities of organic matter, double digging is far more efficient, although of course this can only be done in advance of planting, not among established bushes.
Even if all weeds have been removed before the fruit garden is established, it’s an inescapable fact that more will grow but they must be kept under control if the fruit plants are to give of their best. Persistent weedkillers must not be used because they will remain in the soil and damage the fruit but non-persistent total weedkillers such as the translocated chemical glyphosate or the widely used proprietary contact mixture of paraquat and diquat are perfectly safe if applied exactly as the manufacturers direct. Glyphosate will be needed for deep rooted perennial weeds and a contact weedkiller for annual or seedling weeds, although I only use chemical control for annual weeds when the soil is very damp and unsuitable for hoeing. And of course, the organic mulch placed close to the plants to retain soil moisture will also be beneficial in keeping annual weeds in check close to the plants.