Planting
Having established the most favourable site with suitable soil, the grower is ready to begin planting. The grower must also choose a range of varieties, suitable for their location; for example, later flowering varieties can be planted in more frost susceptible areas, as they are less likely to be damaged by spring frosts during flowering. Most growers have at least 3 varieties in their plantations, as they want to spread their harvesting dates throughout the picking season.
Planting can take place from October to March. The soil must be reasonably dry and crumbly when cultivated for planting, so that the roots are not impeded when they start to grow. It is important to complete the planting work well before any buds begin to swell. Planting in autumn will lead to the development of some fibrous roots capable of supplying the moisture and nutrients required when growth commences in spring.
Blackcurrants are planted in rows as either rooted bushes or cuttings (literally 8″ long strong twigs cut from healthy bushes after defoliation). The first year they are cut back to promote further healthy growth; the second year they grow a sparse crop of ½ tonne/acre and it is not until the third year, or 30 months after planting that they finally yield a crop that begins to pay back the initial planting investment. Most commercial growers average about 100 acres and each acre has around 4,000 cuttings per acre. The optimum yields of 4 – 6 tonnes/acre are usually in years 4 – 8 depending on bush health and season after which time the yield starts to drop away.
Many plantations are planted with grass between every row of bushes – these have to be mowed on a regular basis and on a 100 acre plantation there could be as much as 80 miles of mowing at one time!
Blackcurrants are best established by planting a rooted 1-year old bush which must be from virus tested clean stock, or more commonly, by planting cuttings direct into the cropping site at the spacing selected. This is cheaper and quicker than planting “roots”. Planting cuttings can be done through black polythene mulch as this will help suppress weeds and conserve moisture. However, black polythene provides an ideal habitat for vine weevil, and therefore growers do not use this where this pest may be a problem.
Rooted bushes are normally planted in a furrow, deep enough to accommodate the roots, which is then covered with soil immediately to prevent drying out, and firmed prior to backfilling by tractor. After planting, the shoots are cut off just above the soil level. These shoots may be used to produce cuttings for further planting.
Cuttings are prepared from the basal portion of strong hardwood shoots, discarding the thin tip portion together with weak or mildewed growth. These are planted at a slight angle instead of bolt upright, to help promote rooting. The plantation sizes are generally between 5 and 10 acres. Cuttings, planted as 8″ twigs, never cease to amaze even the most cynical of growers; as in spring these buds break and burst into life, putting down their roots. By the end of the first growing season they may have grown as many as six new branches and up to 2 foot high.
Growing
Each year blackcurrants make new growth consisting of shoots or side branches that range in length from about 5cm to lm. The strongest shoots usually grow from buds at or below soil level, providing valuable replacement for older branches and contributing to the increase in the overall size of the bush. The number of new basal shoots produced each season is small by comparison with the total number of side shoots developing from the branch system.
In order to sustain high cropping levels, production of high quality extension growth has to be maintained to ensure that the total number of flower buds shows a steady increase from one year to the next. It is also important to have a high percentage of young buds, on one-year and two-year old cropping wood as they produce more flowers, larger fruit and normally are more closely spaced compared with buds on older branches. The causes of irregular cropping may be traceable to some of the factors listed below which may adversely affect the performance of the plantation or undermine its yield potential.
