Characterization of selected growing media for greenhouse-grown strawberries

Soilless greenhouse-grown strawberries are a relatively novel crop in North America, allowing for optimization of water and fertilizers management and better control of soil-borne pathogens. Coir often appears as the standard growing medium in this industry. This study aimed to compare the performance of peat-containing to coir-based growing media (GM) for soilless strawberry cultivation under GM-adapted fertigation. Nine GMs, representing the diversity of typical components mostly used (bark, coir, peat, perlite, wood fiber) were tested in a controlled-environment greenhouse over two cultivation cycles (C1: Oct. ‘20–July ‘21 and C2: Oct. ‘21–July ‘22). Mini-tray (C1) and tray (C2) strawberry plants (‘Albion’) were transplanted, then fertigated similarly (EC and pH). Mineral fertigation provided was based on plant demand (determined by volumetric dry down and tensiometers), which represented an average of 47 to 71 L per plant and an EC*L m^‑2 of 2.55 to 3.46. Although shoot and root dry masses did not differ between GM, significant differences were found for total crop yield, fruit size, and sugar content. Total fruit yield ranged from 8.93 to 11.24 kg m^‑2 (893 to 1124 g plant^‑1), and plants produced between 70 and 81 fruits; fruit size fluctuated from 13.1 to 14.9 g and degrees Brix from 6.8 to 7.6 between GM. The highest fruit yield was achieved in peat/wood fiber/perlite GM whereas presence of coir and wood fiber favorably influenced degree Brix. Peat/wood fiber/perlite GM presented physical properties (highest total porosity, highest buffer capacity, highest container capacity), which led to the highest rate of energy used (crop efficiency), appearing highly suitable for strawberry production. GM containing up to 25% V.V^‑1 wood fiber did not affect nitrogen availability in this study. Although 100%-coir GM showed physical properties (i.e. important air-filled porosity) beneficial for the control of pythium and reported the fewest Pythium sp. oospores, no statistical differences were found with peat/wood fiber-based GM. Peat/wood fiber/perlite-containing GM have demonstrated characteristics allowing them to equal or even surpass the horticultural performance of coir-based GM for greenhouse-grown strawberries.