Higher prices means less heating and fertilization. In this newsletter attention is given to effects on plant growth and possible actions.
Some lower costs on fertilizers is possible but always keep in mind that plant quality is much more important than a little lower direct cost of fertilizers.
- The first step is to re use the recirculation water. Do not let the drain water run away. Also make sure there is a good mix between clean water and the feeding solution.
- Phosphate is relatively one of the most expensive fertilizers. Phosphate is important in the plant for energy balance, flowers and fruits. In many cases the phosphate level in the feeding water can be a little lower. In case of pot plants P in the feeding may decrease below 1.0 mmol.
- At a good pH in the substrate the uptake of phosphate and micro elements is a lot better. Precipitation of elements is also lower. The amount of fertilizers can be lower.
- At the end of the cultivation period fertilization can be reduced. In case your are growing on slabs many salts stay behind in the slab, in soil salt levels also often increase especially in the top layer. At the end of growing period the fertilization can be reduced with about 20%. A good EC during growth and no salt accumulation is of course even better.
- Well water and lake or ditch water contain several useful elements. In some cases these elements can be used when calculating the feeding solution.
Fertilizer uptake at low temperatures
Especially the uptake of the elements P, Mg, Fe, is difficult at low root temperatures. Magnesium is a good example, in case of deficiency it shows as a yellowing between the veins. Another danger at low temperatures is a long wet period of the substrate. A wet substrate contains less oxygen. Oxygen is necessary for the roots for an active uptake of elements.
Disease sensitivity at low temperatures
The biggest danger with low temperatures is less plant activity. An active plant is stronger, has a better resistance mechanism and takes up more nutrients.
A plant in stress, low temperatures cause stress, is more sensitive. Also water condensation on the leaves increases the chance for infection by Mildew, Alternaria and Botrytis. Spraying has some effect but a good climate is the best way to prevent infection.
A fungus which is often found at lower temperatures, <15°C, is Thielaviopsis (Chalara). We see this fungus in crops like Lisianthus / Chrysanthemum in soil and in Primula / Viola in pot. The symptoms are black root and base stem rot, it looks like Phytophthora but the treatment is different. When the weather is cold and wet and the substrate has been wet too long Cylindrocladium can show up. This can be on leaves, in Buxus, or on the stem or roots, in for example Rose and Spathiphyllum.