IMPROVING GARDENERS' UNDERSTANDING OF WATER MANAGEMENT IN PEAT AND PEAT-FREE MULTI-PURPOSE GROWING MEDIA: AN ASSESSMENT WITH FUCHSIA

UK gardeners need sound, evidence-based advice regarding water manage-ment of peat-free growing media. However, our understanding of water relations in peat alternatives is relatively poor compared to our knowledge of peat, which has been acquired over many years of practice and research. This experiment aimed to address this knowledge gap and examined the performance of fuchsia ‘Snowcap’ when grown in four different commercially available products based either on peat, coir, wood fibre or green compost. Five different irrigation regimes, determined by regulated deficit irrigation over the preceding 24 hour period, were adopted. The control treat¬ment replaced water lost in this period while the other application rates increased or decreased that amount by 25% and 50%. Growth index, flower counts, upper plant biomass (dry) and two forms of visual plant assessment were undertaken. Growth index of peat- and coir-grown plants were generally comparable across all irrigation regimes and significantly larger (P<0.001) than plants grown in wood fibre- and green compost-based media. Flower number in both peat- and coir-based media declined significantly (P<0.01) when under-watered. Flower number in wood fibre- and green compost- grown plants declined in both over- and under-watered plants compared to the control watering regime but this was not always statistically significant (P<0.05). There was no evidence (P>0.1) of inferiority of coir-grown to peat-grown plants across any of the irrigation regimes for either marketable size or quality. For wood fibre-grown plants, only the control regime produced plants close to marketable quality but these were not considered as good as the peat- and coir-grown plants. No green compost-grown plants were considered marketable.