Just like our houses, greenhouses need regular maintenance to keep them in good condition and to maintain the necessary levels of cleanliness and hygiene. This really boils down to looking after the structure of the greenhouse – inside and out – its heating, ventilation and watering systems and perhaps most importantly, the growing environment itself.
The greenhouse should be regularly checked for any broken or cracked glass – especially after any high winds – and the panes replaced as necessary. The frame too needs to be routinely inspected to make sure it is in good order. While aluminium greenhouses are generally fairly low-maintenance, wooden framed ones will periodically need to be painted or treated with a suitable preservative – making sure that none touches the plants, of course – and any rotten areas repaired.
A regular clean helps preserve the structure of the greenhouse and dirty windows will reduce the light levels – which can lead to propagation problems, such as straggly seedlings. The best times to have a big clean-up are in the spring – just before you begin sowing – or in early autumn before half-hardy plants are brought in for the winter.
Cleaning the outside of the greenhouse is best done on a fairly breezy day, using warm water and a sponge, letting the wind dry the glass off and avoid leaving too much in the way of streaks. Aluminium framed greenhouses can be particularly prone to collecting grime underneath the joints between panes – a jet-wash attachment for the hose or gentle scraping with an old plant label will often shift the dirt very successfully.
Regular, thorough cleaning of the interior of the greenhouse is absolutely essential, not only to create pleasant surroundings in which to work, but also as a major part of controlling pests and disease. It has often been said that it would be difficult to over-emphasise the importance of cleanliness to greenhouse management – so doing a thorough job here can save untold hours of trouble!
When starting out, make sure that the electricity is turned off, the heaters and other electrical equipment unplugged and the sockets covered. Unless the temperature outside is too cold, remove all the plants, containers, pots and staging – protecting any tender or half-hardy plants with horticultural fleece or putting them inside a shed or garage while you work. This is an ideal time to inspect each plant carefully, picking off any infected or damaged leaves and discarding anything which is clearly dead or dying.
All the spent compost or grow bags should be discarded and the floor swept to remove fallen leaves and general rubbish and then any beds weeded. With the greenhouse emptied, the glass, paths and any brickwork should now be thoroughly cleaned with warm water and a suitable disinfectant, allowing them to dry thoroughly before returning the evicted plants to their rightful places.
Check the Equipment
Heating, ventilation and irrigation systems are vital to the greenhouse – so they should not be forgotten or neglected. Regular checks – and servicing as appropriate – of these key items are essential, whether you do it yourself or call in outside help. At the same time, pots, containers, staging, propagation benches, capillary matting and the like should also be regularly sterilised to reduce the risk of pests and disease and any lighting systems inspected.
Maintaining the Growing Environment
The warm, humid environment of the greenhouse is ideal for many pests and diseases, which can spread depressingly rapidly if given the opportunity, but keeping the greenhouse clean and tidy can significantly reduce the likelihood that they do become a problem. Supporting those plants which need it – and tying in their emerging shoots – coupled with a regime of pruning, pricking out, potting on and pinching out plants as necessary and a thorough weeding around the beds should help.
Providing some form of shade as appropriate can also be of great benefit – avoiding leaves getting scorched and the almost inevitable subsequent disease attacks that the weakened and damaged plant will suffer. It is important to be mindful that the ideal growing conditions for plants which the greenhouse offers are just as tailor-made for any number of bacteria, fungi and other unwelcome guests. Part of routine greenhouse maintenance also involves being constantly on the look-out for pests and diseases – such as aphids, red spider mite, mealy bug, mildew and botrytis – and being ready to treat them promptly.
Spring cleaning is, clearly, every bit as important to our greenhouses as our homes, but in addition to a one-off annual tidy-up, routine maintenance is essential to keep everything running smoothly. However, with a little attention to one or two key essentials, keeping our greenhouses in peak condition need not present too much of a problem nor take up too much of our time.