Which is better, wood or metal, for greenhouse construction?
For ease of maintenance, aluminium is the best although I still think that apart from the most costly power-coated aluminium, wood looks better.
Aluminium greenhouses are cheaper to make and, so usually cheaper to buy than a wooden house of comparable size. A wooden greenhouse usually has thicker glazing bars than an aluminium building and this results in less efficient light transmission, Against this, however, must be balanced the fact that the wooden framework retains heat better than the aluminium one. The maintenance of a wooden greenhouse is greater than that of an aluminium one because of the need to apply paint or preservative to the timber.
Wooden greenhouses are sometimes claimed to be harder to clean and disinfect but this is only marginally true. I always used to argue that aluminium greenhouses were more difficult to keep warm effectively in winter because of the problems associated with attaching insulating materials to the framework. This situation has now improved, however, and efficient clipping systems are available. Structurally, an aluminium greenhouse is less stable and is more likely to be damaged by severe winter gales.
Is it worthwhile installing a greenhouse heating system?
Yes, as otherwise you aren't gaining the greatest benefit from a costly investment. We have a range of greenhouse heating systems to choose from.
The most efficient and easy to control greenhouse heating systems are thermostatically controlled electric fan heaters. If you don't have mains electricity nearby, then I recommend bottled gas. Paraffin heaters are the cheapest type of heater but least readily controlled and some plants such as orchids, can be damaged by the fumes. It is important to decide carefully exactly what temperature you require in your greenhouse as raising the temperature by around 2.5 ° C will approximately double your heating costs. Finally, do consider fitting internal partitions in order to heat only part of the greenhouse and don't forget the value of modern plastic insulating sheet (especially of the bubble type) in cutting down heat loss.
How frequently should a greenhouse be disinfected?
Once a year, ideally in autumn after tomatoes and other summer crops have been removed. Used plenty of warm soapy water and a proprietary garden disinfectant.
There is no point spending time and money on raising plants if you don't take sensible precautions to minimise the likelihood of them succumbing to pests and diseases. The greenhouse must be completely stripped of its plant life if the cleaning is to be done properly; partly to facilitate access to all the nooks and crannies, but also because most of the disinfectants that you are likely to use are potentially damaging to green plants.
What are cloches and what are they used for in the garden?
Cloche is a French word that means a cover, a bell or a bell-shaped object. Although no longer bell-shaped, a cloche in gardening is a translucent cover usually used for placing over plants with the objective of lengthening the growing season. It is used especially with certain types of vegetable and with strawberries. We have a range of cloches to suit gardens of all sizes.
Cloches achieve the result of lengthening the growing season simply by providing protection from frost and enhanced warmth at the beginning of spring and the end of autumn. So, vegetables such as lettuces can be sown or planted outdoors several weeks before it is safe to place them out unprotected, whereas, in the autumn, by placing cloches over growing plants, it is possible to extend the cropping season well beyond the time when frosts and lower temperatures generally have taken their toll. Where I believe most gardeners miss out on the use of cloches is in not using them to pre-warm the soil outdoors before spring sowing. Quite frequently, you will read directions on seed packets to the effect that the seeds should be sowed outdoors in late March or early April 'as soon as the soil begins to warm up'. In many years, in many parts of the country, the soil has barely begun to warm up by early April and so seeds sown then will stay, ungerminated, for a considerable time, at the mercy of insect pests and fungal diseases. Placing cloches over the seed bed ten days or so in advance of sowing will make a great deal of difference to the subsequent seedling emergence.
What is the answer to keeping greenhouse plants healthy when you go away on holiday?
There is no need to rely on the good nature of your neighbours. Choose from our range of automated watering systems and greenhouse ventilators so you can leave your plants with every confidence that they will thrive in your absence.
Few gardeners go away long enough for their plants to starve in their absence so feeding can await their return, but keeping them cool and well watered is a necessity. If you have manual vents, leave them all open therefore; in the middle even of a British summer, little serious harm is likely to ensue as a result of the night-time drop in temperature. If you don't already have them, fitting automatic vents is well worth considering. Ensure also that the greenhouse has adequate shading; various types of blinds (some automatic) are now available and another option is white paint-on shading . Do use a 'paint' specially formulated for the purpose however; not only are simple emulsion paints liable to be washed off by the inevitable summer rain, but they may also filter out some of the beneficial wavelengths of the sun's radiation. Watering is best done by an automatic watering system , operating through a simple timer attached to the nearest tap. A system of trickle irrigation lines can then run from this to benches or individual plants. Less sophisticated, but no less valuable for pot plants standing on the greenhouse bench is capillary matting ; a plastic water-absorbing cloth that is laid over the bench and on which the pots are placed. A wick can be used to deliver water from a small reservoir tank and so ensure that the matting remains uniformly moist. If you have plants in growing bags, then simple plug in reservoirs are ideal to ensure that the compost within doesn't dry out unseen; even when you are at home.
Why do I never have good tomato crops in the soil of my greenhouse.?
Almost certainly because a disease called wilt has built up in the soil. Resting the soil from tomatoes will help it to die away but a better answer is to switch to some form of container growing such as ruing culture, pots or growing bags.
Whenever any type of plant is grown repeatedly on the same site and in the same soil, there is always a risk of running into problems. After a few seasons of growing tomatoes in the same soil of the greenhouse bed, the plants may show signs of poor and stunted growth, quite commonly with a very sad looking droop of the leaves. If you uproot one of the unfortunate plants and slice lengthwise through the stem, there will almost certainly be a dark stain within the tissues. This is the tell-tale sign of a disease called wilt which is almost impossible to eradicate. There are three main alternative methods; growing bags, pots and ring culture. Growing bags are the simplest, each full-size growing bag being used for three plants. The second alternative is to use large pots; 25 cm diameter filled with John Innes No.3 potting compost. The third alternative, ring culture pots , is probably the most popular and most efficient way of growing greenhouse tomatoes. The principle of the technique is to induce the plants to build up two different root systems, one within the compost of a bottomless pot that serves for feeding, and a second, lower down in a gravel bed on which the pots stand, for the purpose of taking up water.
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