Greenhouse Buying Guide
From overwintering frost sensitive or tender plants, growing cucumbers or chillies, to propagating from seed or cuttings, a greenhouse is a great addition for any keen gardener.
A greenhouse opens a world of exciting options, and by offering protection from late frosts, it means your growing season can start much earlier and extend well into the autumn or even winter. No matter how small, or large, your garden is, there’s a greenhouse that will be the perfect fit.
When choosing the most appropriate greenhouse, there are a number of things you need to consider, such as size, location, and the materials from which it's constructed. This guide will help you make the right decision based on your needs.
Which greenhouse is right for me?
The first thing to decide upon is where you are going to position your greenhouse, as this will often determine what size you can accommodate. Don’t forget to allow enough room to access the sides of the structure for cleaning and maintenance.
The ideal position would have no shade, so be aware of any shadows cast by trees or buildings.
A greenhouse running north to south offers maximum summer light, whereas, east to west offers marginally more winter light.
If you intend to use electric heaters or lighting, then bear in mind the access to power.
Ideally, a greenhouse should be situated in a sheltered spot, which offers protection from the prevailing wind. Choosing a flat area will make laying a base simpler.
Having identified the most appropriate location in your garden, you can now measure up and decide what size greenhouse you want.
- The taller the eaves, the better the light distribution is, so aim for a height of at least 1.5m.
- Be sure to allow enough headroom so you can stand and move around comfortably.
- A width of 6 feet or greater will allow for staging or beds on both sides of the greenhouse.
- It’s best to go for the biggest size you can accommodate and afford.
- Double sliding doors are both space saving and very practical for moving large plants in and out of the greenhouse.
Different frame options
- Strong and sturdy
- Tends to be better at maintaining a steady temperature
- Higher cost
- Will require maintenance from time to time
- Softwoods will need treating, but may still rot over time
- Better for light than plastic alternatives
- Easily replaced if damaged
- Most easily damaged type of glazing
- Shatters into large, sharp pieces so dangerous if broken
- Better for light than plastic alternatives
- Stronger than horticultural glass
- Toughened glass is more robust and shatters into smaller pieces when damaged, therefore making it safer around children and pets
- Higher cost
- Virtually indestructible
- Better insulation than glass so can save on heating costs
- Lower cost than glass
- Double wall panels can reduce light transmission
- Can suffer from condensation
- Can become cloudy over time
Learn more about
Heat and light
Good ventilation is essential for regulating temperatures, encouraging healthy plant growth and helping to combat pests and disease. The most effective form of ventilation is roof vents, ideally on both sides of the roof. Louvred side vents can be useful too. A great way to keep your greenhouse at the correct temperature is through automatic vent openers; these are especially useful if you are unable to get out to your greenhouse on a daily basis.
Plants can easily be scorched by direct sunlight, so to reduce the intensity of the sun you can introduce shading. There are a number of options available, including external or internal blinds, shading netting, which is a convenient and low-cost choice, or you can paint your greenhouse with shade paint, which is usually applied from late spring and washed off in the autumn.
Tender plants will require a heat source as they need to be kept at a minimum temperature of 7°C all year round. Whilst gas and oil heaters are very portable and cost-effective, they do require regular ventilation, so electric heaters are the best and safest solution. You can minimise your heating costs by insulating your greenhouse with bubble polythene in the winter, sealing any drafts and by replacing cracked or damaged glass.
Most greenhouses are supplied for self-build, although the price of some timber models does include professional assembly.
Ensure that the greenhouse is securely anchored to whatever foundation or surface it's positioned on. Palram offer an anchoring kit for its range of greenhouses that can withstand winds of up to 100mph.
Aluminium greenhouses are generally supplied with a base, usually around 5”/12.5cm high, but not all timber frame models are, so check before you buy.
Most greenhouses sit on concrete, paving slabs or gravel over a base of hardcore and sand, which provides good drainage and is particularly suitable if you intend to grow plants in containers or gro-bags. However, if you intend to grow crops in your greenhouse, it can sit directly onto soil.
Unless you live in a listed property or a designated area of outstanding beauty, it’s unlikely you’ll need to seek planning permission as long as the following apply:
- The greenhouse is for your domestic use only
- Along with any other outbuildings, the greenhouse covers less than 50% of your property’s land
- It is less than 4m in height
- If within 2m of the property’s boundary, the height of the eaves can’t exceed 2.5m
- The greenhouse is not nearer to a public highway than the original house
These are not definitive guidelines, so it’s best to check with your local planning authority if you have any concerns.
Aluminium frames will need little ongoing maintenance, other than cleaning with detergent or a damp cloth from time to time.
Timber frames will need regular application of stain or oil as required.
Guttering should be cleaned, checked and any debris should be removed when necessary.
Glazing should regularly be cleaned, both inside and out.
Internal surfaces should be cleaned annually with a disinfectant to help protect plants from disease and pests.
A wide variety of shelving, known as staging, is available to maximise the growing space for any greenhouse.
A potting bench is a useful addition, especially if you intend to grow plants from seed.
A greenhouse can require a lot of water during the warmer months, so it's a good idea to install a rain collection kit and a water butt.