Soilless Cultivation For Herbs

The production of crops without soil, typically by hydroponics, using nutrient-enriched solutions with or without growing media, offers a unique opportunity for the Welsh horticulture sector. Hydroponic systems are particularly beneficial when producing herbs which can achieve high marketable yields and be sold at a premium to retailers for local consumption.

Fresh herbs such as basil, parsley, coriander and mint, are increasingly demanded by consumers as tastes broaden and there is a sustained focus on healthy, nutritious food. Herbs are well placed to benefit from this trend. Small quantities of fresh herbs can greatly enhance the flavour of any dish and while these may be integral to many regional cuisines such as Asian cookery, many consumers seek to use herbs for flavouring a range of salad or sweet dishes.

From a horticulture perspective, herbs represent an ideal locally produced product: it is a high throughput, high value product which can exhibit rapid drops in flavour and quality in extended supply chains. By increasing the availability of locally-grown, high quality herb products, growers will be able to exploit an increasing consumer demand and increase the profitability of their growing enterprise. Welsh-grown fresh produce also aligns with the long-term vision of the Welsh Government for horticulture, to diversify traditional horticulture output that meets consumer demand for local produce. Welsh-grown herbs are a sustainable commodity that can either be eaten fresh or used in Welsh-made food and drink products.

Herbs are a fast return on investment crop for a hydroponics enterprise, either as a new business or as a development from an existing business. Herbs can be grown in many existing glasshouse or polytunnel structures, including those developed for ornamental use allowing growers to seamlessly expand their existing enterprise. Herbs grown in hydroponic systems can be grown at high density with short crop cycles, producing 3-to-4-fold increases yield per unit area compared with traditional methods. Guttergrown basil can yield 1.5-2kg/m2 cropping within 45 days for mature plants, while parsley can achieve 3 – 5 kg/m2 within a 28 day growing period.

High planting densities also increase the efficacy of biological controls for pests and diseases in both the root and shoot zones compared with growing in the soil. Low labour costs associated with stacked or table-height production, and the ability to control the growing environment means that optimum resource efficiency can be achieved while offering a highly uniform and consistent product that has the potential to be grown year-round under protection, with supplementary and replacement lighting.

While soilless cultivation methods can be started on a small scale using simple technology, these techniques can be combined with innovative growing technology such as lightemitting diode (LED) to promote photosynthesis and extend daylength; crop sensing to monitor temperature, water use, crop health and pest and disease outbreak; carbon dioxide enrichment to increase carbon fixation by photosynthesis and stimulate high marketable yields and excellent crop quality. When technologies are combined very high yielding and efficient crop production systems can be developed.

This toolkit has been written as a practical guide for growers who are seeking to diversify their business using hydroponic techniques.