In this section, you will find the growing methods in use, the growing techniques, crop protection, disease control and variety choice of tulips, hyacinths and narcissus.

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4.8 Rooting medium The substrate most commonly used for tray forcing is a peat mixture with sand, which must meet the following standards: - The rooting medium must have the right composition. A good mixture is 40-80% 1-year-frozen black peat (garden peat) + 60-20% peat moss. Preference is given to a mixture of 60% garden peat and 40% peat moss. To make sure that the plants do not fall over and to improve the water-air ratio in the substrate, but especially to control the fungi Pythium Trichoderma and Botrytis cinerea, it is advisable to add disease-free potting soil or course sand (15%) to the mixture. - The structure should be neither too course, nor too fine. A rooting medium with a course structure is difficult to work and will lose water too quickly. A structure that is too fine reduces the water-draining capacity and the air content of the soil. Flooding must be avoided. During transportation moist soil will settle even more, resulting in even further deterioration in the soil structure. - Good water and air balance. Provide a maximum of 80% moisture content and minimum air content of 10% (at a suction tension of -10 cm). Rooting mediums processed with peats that have shrinking qualities are unsuitable. A maximum settling of soil of 30% is allowed. - The rooting medium should not be too acid. Low pH levels will lead to root rot. A pH level of 6-7 is ideal. Even if an analysis is supplied with the rooting medium, have it tested. If the pH level is too low, the medium requires additional treatment. 1 kg of calcium carbonate per cubic metre will raise the pH value by a factor 0.3. - The medium should not be too salty. High salt levels in the soil will affect the rooting of the tulips. A maximum of EC 0.5-1.0 at 25°C applies. This includes the addition of any fertilizer, which we do not recommend. - The medium should not be too light. 1 cubic metre of slightly moist rooting medium must weigh at least 300 kg. If this is not the case, the plants will not sit tightly in the trays. - The medium must be disease-free.