Flood table pack with 10 pots: system, grow medium and nutrients

The 10 pots supplied are 4-litre fabric pots, and the fabric lets air in through the walls. Your root balls therefore breathe over their whole surface instead of receiving air only from the top, which limits root circling against the sides. They also dry out through the sides, however: on a windswept terrace in midsummer, check the grow medium rather than applying a fixed frequency. On the 86 x 86 cm of genuinely usable tray space, the 10 pots leave room between the plants; you can fit up to 32 pots of 15 cm if you are growing lettuce or herbs, provided you keep them at the same stage, since they all share the same reservoir and therefore the same solution.

The TriPart range, available in mains and solar versions, splits the nutrition into three. Micro, an NPK 5-0-1, provides calcium, iron and trace elements and stays present from seedling to harvest. Grow, a 3-1-6, supplies the nitrogen and potassium for growth. Bloom, a 0-5-4, supplies the phosphorus and potassium for flowering. In full growth, allow for your reservoir 1.8 ml of Grow, 1.2 ml of Micro and 0.6 ml of Bloom per litre; in flowering Bloom rises to 2.4 ml. Pour each bottle separately into the water in your reservoir, never one concentrate into another. The Micro supplied is the soft water version, intended for water below 70 mg of calcium per litre, rainwater or osmosis water; with harder tap water, the hard water version of Micro takes its place.

Offered as a third version, Pro Organic comes in two bottles instead of three and replaces mineral salts with entirely plant-based materials. The dosing ceiling is 2 ml per litre: Grow goes from 0.25 ml at the start to 2 ml in growth, and Bloom holds at 2 ml in flowering. The fundamental difference lies in the pathway: these materials must be mineralised by micro-organisms before they can be absorbed, which makes the nutrition slower and more buffered beneath your plants. It also means you must maintain the reservoir and the pump more diligently. The range complies with European regulations on organic farming. This microbial activity slows markedly below 15 °C, so a solution kept at around 20 °C gives you nutrition that keeps pace with the plants' needs.

The 100 litres of solution circulate in a loop for 2 to 3 weeks. The plants take up ions unevenly, evaporation concentrates the rest, and the pH shifts from one day to the next. Outside the useful range, elements that are in fact present in your reservoir become unavailable, and you see your plants stall even though the solution is correctly dosed. Aim for 5.5 to 6.5 up to the growth stage, then 6.4 to 6.8 from pre-flowering, and always adjust last, once the nutrients have been added. The powdered corrector is dosed at around 1 g per 5 to 6 litres, dissolved before being poured in. The article on pH regulation explains how to follow its trend over time. As the pump only runs during the flood cycles, stir the reservoir after each addition before taking the check reading again.

The number of flood cycles is set by observation rather than by a ready-made table. With the coco fibre supplied, start with 3 cycles during the day, then watch: a grow medium that never dries on the surface calls for removing one, a pot that dries out in late afternoon for adding one. The season shifts this setting, as a plant in the full heat of summer drinks noticeably more than in March, and a table placed outdoors also reacts to wind. At night the cycles stop, as transpiration is almost nil and a permanently waterlogged grow medium ends up suffocating the roots. Finally, lift a pot at the end of the day: its weight tells you in a second whether the grow medium has dried between two flood cycles. In the solar version, the pump delivers 300 L/h with a head of 1.2 m and a 5 m cable, and its built-in timer sets the cycle at about 10 minutes per hour: the choice of grow medium is then your remaining lever.

A little solution stays in the tray between two cycles, and it is this that must be kept in the shade, as algae take hold within a few days on a lit surface. So cover the open surface with empty pots or a sheet. At the end of a crop, empty the tank, rinse it with clean water and run the pump strainer under water, since a clogged filter lengthens the filling time without anything signalling it. Finally, check the levelling of the tray before restarting, as a sloping tray leaves one side dry at each flood. Once a season, circulate diluted white vinegar if your water is hard, then rinse twice before making up a fresh nutrient solution, since limescale reduces the pump's flow long before it becomes visible on the walls.