With the unseasonably warm weather continuing this week, time is running out to prepare container nursery stock for the winter months ahead, warns ICL technical manager Andrew Wilson.
“Even during recent mild UK winters plants are often lost or rendered unsellable due to winter injury,” says Andrew. “The main causes being waterlogging, inadequate conditioning of plants pre winter and lack of effective winter protection. Take action now to help plants survive harsh winter conditions to minimise losses and optimise quality ready for the spring.”
Shorter cooler autumn days initiate plant dormancy improving resistance to freezing injury. However if a mild autumn is followed by a sudden cold snap plants may be insufficiently prepared.
“It is a good idea to keep irrigation to a minimum through autumn and winter and avoid high N feeds and late pruning, both of which encourage soft growth,” advises Andrew. “Switching to higher Potassium feeds will promote hardy compact growth. Incorporate Osmocote Exact Hi.End, ICL’s fourth generation controlled release fertilizer, in to the growing media ensures balanced nutrition entering winter, as the nutrient release slows down as temperatures drop.”
Andrew advises regularly ventilating polytunnels and glasshouses to reduce fungal infections, particularly Botrytis. To help avoid waterlogging he recommends using a specific nursery stock growing media with high air filled porosity, such as Levington Advance CNS. By promoting effective winter drainage, roots are healthier and at lower risk of diseases such as Pythium and Phytophthora. Entering winter it is important to ensure beds are well drained and sand beds are drained down, while hand watering can be extremely effective for keeping water use to a minimum.
Last but not least Andrew says it is important to ensure plants have adequate winter protection. “Ensure polytunnel skins are replace, as necessary, before winter and avoid plant desiccation, which occurs in cold windy conditions when roots are frozen and leaves dry out leading to brown scorched leaves.”