The cultivation of small fruits currently represents, globally, a sector with a large margin for growth. In Italy alone, between 2016 and 2020, consumption increased by 64% and, in the first half of 2021, the growth rate was 40% compared to the same period of the previous year (source ‘Italian Berry Day’ – Macfrut Rimini 2021).
Of all the small fruits, after the blueberry, the raspberry is the one with the greatest potential and on which new farmers are focusing their attentions, driven by the increase in demand.
Raspberry cultivation in pots is one of the most successful substrate crops among fruit growers all over the world.
There are many varieties of this plant which, theoretically, would allow it to be grown in any type of soil.
Why, then, choose pot cultivation?
The lifespan of a small fruit plant (raspberries, blueberries, blackberries, etc.) is on average about 10 years and depends not only on the cultivation technique but also on the type of soil: this must not be too heavy or limey, subject to water stagnation or periods of extreme drought.
It goes without saying that the very ageing of the plants implies a reduction in the fruit yield, as well as the risk of the development of possible phytopathologies. And this is why the economic life of a plant is, as a rule, shorter than the physiological life of the plants.
To ensure that the life of a plant can be ten years, it is important to have a strict control of the soil as well as to check that the plants are healthy, free of virosis, mycoplasmosis and root phytophthora.
Cultivation in pots is undoubtedly more onerous but is amply compensated for by the high yield and quality of the fruit obtained as it allows scrupulous control of the health of the plant and, above all, to be able to respond to its needs in a precise and timely manner. Firstly, by using primary resources more responsibly, growing in pots allows a reduction in environmental impact.
Irrigation and fertilisation are two of the fundamental parameters for a good yield of the system: irrigation water must be filtered and acidified so that the pH is 5.5/6 (in the presence of calcareous water, citric acid can be used, which is very effective, non-dangerous and easy to use); the drip irrigation system must guarantee the possibility of irrigating, even 10 times a day, in the hottest periods.
Fertilisation should be carried out more frequently than for other types of plants and should be done with soluble fertilisers. Wherever possible, fertilisation with water-soluble fertilisers is highly recommended, (quickly assimilated by the plants, they are not wasted or dispersed in the soil) and should be done together with irrigation (fertigation), i.e. whenever the plant receives water. The composition of the fertiliser – and the ratio of nitrogen, potassium and phosphorous – will have to be adjusted during the flowering and harvesting phases and will be closely linked to the analysis of the irrigation water, the type of pot used and the type of substrate. The substrates used for raspberry cultivation are generally coconut fibre and white peat, more frequently a mixture of the two. Water management is made easier by the use of coconut fibre in high percentages. For raspberries, 5 to 8 litres of substrate are generally required, but these parameters can change depending on the variety of the plant. For an economical – and at the same time efficient – planting system, plan to use pots of around 10 to 11 litres with two seedlings placed 40 cm apart, so that there are 5 plants per linear metre. Each pot should be fed by 1 or 2 drippers. In the case of above-ground cultivation, it is imperative that a covering tunnel be created, as the raspberry must be placed in half-shade or protected by a shade cloth, as well as a rain cover; the latter is particularly important as this is a fruit that is prone to mould development and is mainly intended for the fresh market. In addition, it is necessary to use support structures for the plants – either with wood or iron – in order to support the growth of the outer branches.
Growing in pots makes it much easier to control and estimate the amount of water needed by the plant. As with field cultivation, high-precision instruments can be used, but also, more simply, the drainage coming out of the bottom of some pots can be collected and compared to the amount of irrigation water given to those pots: a drainage of 5%-10% is ideal. This check should be done at least once a week, or more frequently in case of rain or drought.
Plants grown in pots not only have the advantage of being healthier, but also of being able to be hypothetically planted at any time of the year as they have roots (grown for the minimum time of one year) that can easily and safely take root. Another, not secondary, aspect of pot cultivation is the simplicity and flexibility with which transport and handling can be organised. The transport of potted plants in the ORSA model, for example, is optimised thanks to the square-conical design of the pot and the dimensions that make it easily adaptable to the space on the Danish-trolley.
For smooth above-ground cultivation, it is necessary to use containers with a structure that encourages optimal plant development and maintenance in terms of oxygenation and root drainage, as well as ensuring optimum performance in hot and cold conditions without the risk of breakage due to drastic temperature changes or due to daily mechanical handling within the nursery.
ORSA, and the more innovative ERACLE FRUIT, with its cross-shaped bottom, numerous openings for easy drainage and the distance of the bottom from the soil to prevent stagnation, are the ideal pots for growing raspberries. ORSA is available in various capacities including 11 litres and 15 litres. ERACLE FRUIT is available in 6 litre and 10 litre capacities.