Winter injury - Watch out for waterlogging in outdoor containers. Drought damage can occur on evergreens on sunny days when their root systems are frozen.
Apply an anti-transpirant (avoiding frost) to prevent unnecessary water loss. Make sure that vulnerable crops, including spring-flowering species, are suitably protected from strong winds by windbreaks, Cosytex or fleece. Plants that are pot-thick will have better root protection because less pot surface is exposed.
Heathers - Ericas and callunas can suffer from Rhizoctonia now, particularly protected crops and young overwintering plugs. Control with Prestop, Rovral WG or Switch. Include a wetting agent in the spray tank for better compost penetration.
Winter wash - Certis Spraying Oil will provide dormant-season control of spider mites, mealy bug and scale insects. Avoid frost to prevent foliar damage. Consider applications onto hedges that suffered insect damage earlier this year. Good foliage penetration will be required for some conifer species.
Rust - Check Mahonia 'Apollo' during December. Control infections with Signum (EAMU 2012-2141) avoiding frost before and after application.
Weed control - As well as Flexidor and Butisan S, other products can be applied during the dormant season to control weeds that have built up on compost surfaces. Devrinol can be used between 1 November and the end of April. Products containing glufosinate-ammonium provide good contact control of pearlwort. Avoid drift onto nearby crops showing green tissue. For bittercress, willowherb, pearlwort and mouse-ear chickweed, HDC project HNS139 found that Skirmish (not on buddleia, escallonia, Hebe or veronica), Sumimax (EAMU 2008-2881 - not on escallonia, Hebe or vinca) and Chikara worked well as winter treatments. Chikara and Sumimax (EAMU 2008-2881) worked well on groundsel.
Vent gear - Grease up vent gear - motors, racks and bearings can get damaged during the busy summer months through lack of maintenance. Get your staff to read Health & Safety Executive leaflet AIS12 - it provides good safety advice for glasshouse work.
Heaters - Use paraffin with low sulphur content in direct-fired heaters. Vent glasshouses and polytunnels at least once a day to reduce risks of foliar damage from sulphur fumes (paraffin) or ethylene (gas) as well as Botrytis infections.