In this article. Keep reading to find out the optimal greenhouse materials and sizes to the best features, accessories and heaters, plus our top tips on how to build a greenhouse. Make more of your garden - get our free Gardening newsletter for top tips from our experts. We run through the pros and cons of some of the most popular greenhouse types:. Most people opt for a 6 x 8ft or 8 x 10ft freestanding greenhouse.
Typically square or rectangular with an apex roof, you can get them in a variety of sizes and they allow light in from all four sides. Consider making use of a back or side wall with a lean-to greenhouse. The initial purchase costs are similar to a freestanding model, but it takes up less space and you only need access around three sides. It is also cheaper and easier to keep warm. A mini greenhouse is like a glazed cupboard with shelves that sits on a patio or under a window, using a house wall or garage as protection — perfect if space is limited.
It will protect trays or pots of young plants from late frosts in spring, and encourage borderline crops such as peppers to ripen. Ideally, a mini greenhouse should face east or west. South-facing ones overheat in spring or summer unless shaded and north-facing ones suit only shade-loving plants.
We've trialled lots of tomatoes using greenhouses to grown them in. Find out everything you need to know about how to grow tomatoes in our expert guide. Most greenhouse frames are made of aluminium, but wooden greenhouses are also available and many gardeners find them more attractive to look at, although they need more maintenance than metal frames. Wooden greenhouses are less common and typically cost more than their aluminium counterparts. Softwoods, such as deal pine , are vulnerable to rot, even if the timber has been treated.
Naturally durable timber — usually western red cedar — can be left to age to a silver-brown. For looks, a western red cedar greenhouse is hard to beat. Look for manufacturers that offer a guarantee against rot. Here are some other pros and cons to be aware of. If a shed is more suited to your needs then here's our expert shed buying guide. Horticultural glass is inexpensive and easily replaced, but if you are concerned about breakages or safety, you can opt for a plastic greenhouse.
Plastic greenhouses have twin-walled polycarbonate sheets. Polycarbonate greenhouses let in sufficient light for plant growth initially, but, over the years, they can become cloudy and do not age well. Toughened glass is a better option, particularly if the greenhouse is on show.
Toughened or safety glass is stronger than horticultural glass and, if it does break, the resulting pieces are not so sharp. Another option is self-adhesive safety film. This is a transparent film that is applied to horticultural glass.
Greenhouse gardening may be brand new for you and you might want to start with something small and inexpensive. Perhaps you already have a beginner greenhouse and you are ready to invest in something more substantial. Whatever the goal, you should take thoughtful consideration before you decide to purchase a greenhouse. You may be asking yourself, with so many hobby greenhouse kits to choose from, how do I select a greenhouse kit? This article will highlight some important features to consider during your quest for a greenhouse, and help you select the greenhouse kit for your plants and your lifestyle.
Look for a greenhouse that provides the right amount of light for your plants Everyone knows that sunlight is important for plant growth. It may surprise you to know, however, that natural sunlight is not the best light for plants. In fact, direct light may even damage plants. The same harsh rays that cause sunburns in people also can burn your favorite foliage.
Studies show that diffused light, the same light provided by Solexx greenhouse panels, is the best light for growing. Growth rates increase 20 to 30 percent under diffused light when compared to plants grown under more direct light. Diffused light reaches your plants from all angles and produces fewer shade spots.
As a result, the plants develop healthy, compact growth in your greenhouse. Light diffusion of greenhouse coverings differs greatly. Glass and most single-walled greenhouse covering materials provide minimal, if any, diffusion.
Polycarbonate greenhouse covering provides more diffusion than glass, but far less than Solexx. Solexx greenhouse panels provide the best diffused light available. Even on a cloudy day, a Solexx greenhouse is bright inside. Unlike other greenhouse covering materials, Solexx greenhouse covering reflects the light throughout the entire greenhouse structure.
Too much light causes excessive heat in the greenhouse. As a consequence, plants waste energy through transpiration, much like sweating.
This stresses plants and reduces photosynthetic rates. More plants actually die in a greenhouse from overheating than from the cold. Some garden centers provide UV-stabilized polyethylene bubble wrap for this purpose.
We recommend that you choose wrap with large bubbles as this has better insulating properties and lets in more light. Some greenhouses are designed with clear coverings or panels, while other models have translucent or opaque coverings. And some greenhouse models have semi-diffused covers which provide some of the benefits of both clear and diffused models. Clear panels deliver direct light while opaque panels provide diffused light. If you want to buy a greenhouse to germinate seeds and grow starters which will be transplanted outdoors, then a clear covering has the advantage of bringing full, direct light to the starter trays.
This warms the soil and encourages germinating seeds to sprout and develop into a vigorous starter plants for transplanting. Examples of clear-covered greenhouses are the Nature and Snap and Grow greenhouse models. If you plan on growing the plants to maturity in your greenhouse, a diffused covering has the advantage of providing even light for balanced foliage growth as well as preventing hot spots within the greenhouse.
While it may seem counterintuitive, diffused light provides superior light for growing plants. Diffused light may appear to be less bright than direct light, but the light that generally produces the most efficient photosynthesis is not visible to the human eye. With diffused lighting plants develop a more balanced, compact structure. The Solexx greenhouses all have diffused covers.
For gardeners who want a dual-use greenhouse, the semi-diffused cover provides the benefits of both clear and diffused covers. The semi-diffused covers provide an all-purpose greenhouse. As a general rule, clear greenhouses provide warmer, direct light which benefits seed propagation. Greenhouses with diffused coverings are ideal for growing crops full-term. Greenhouses with semi-diffused covers provide the benefits of both. Some greenhouse designs have diffused covering on the roof and clear covering on the sides, which offers some benefits of each.
Sunlight breaks down plastic over time. For maximum life expectancy, greenhouse framework and glazing should be UV-treated. Look for greenhouses that are UV-certified. Some greenhouse coverings have a UV coating on the outside and you have to be careful not to damage the outer coating. The covering material of your greenhouse needs to be strong enough to resist breakage from hazards associated with your growing region. If there are trees nearby, the covering should resist falling branches.
It should be impervious to hail and have sufficient impact strength. If you live in an area with winter snow or icing, the greenhouse covering must be strong enough to support the extra weight. The shape may also play a role in load strength and how your greenhouse will shed rain and snow. From classic peaked roofs to hexagons and geodesic domes , many different types of greenhouses are available. You should be able to configure the shelving to suit your greenhouse gardening plan. Shallow shelves are ideal for germinating seeds and establishing starter plants, but taller shelf spacing is needed for mature plants.
Some greenhouses are designed to accommodate extension kits which give you additional more growing space. Materials used for the glazing, or outer covering, of greenhouses have come a long way since the old-fashioned glass greenhouses. Different types of plastic, and tempered glass, are used today for greenhouse applications. These come in the form of sheets or panels, and range in clarity from clear to diffused.
Glass and clear plastic function in basically the same way, by allowing light to pass through while trapping heat inside. Plastics are generally lighter weight and less expensive, but not as durable to weather and age. Glass greenhouses cost more to build initially, but hold up better over time. If your region has cold winters, i. Tempered glass panes are very strong and impact-resistant, and will withstand expansion and contraction during seasonal temperature changes. Single-pane thickness of 3mm is adequate for greenhouses, but 4mm thickness is stronger and provides additional insulation value.
The edges must be protected during installation, as they will shatter the pane if hit with a hard object. Tempered glass is more expensive than polycarbonate panels, but it is more durable and scratch-resistant. Tempered glass is clear, and provides no diffusion. Fiberglass is translucent and provides well-diffused light. Fiberglass retains heat more efficiently than glass. Fiberglass greenhouses are usually corrugated to provide rigidity. The outer gel coat will become sun-baked, often within 6 — 10 years depending on exposure.
The surface eventually becomes etched and yellowed, and dirt and debris can collect in the valleys. UV-treated polyethylene film is commonly used to cover large commercial greenhouses because it is relatively inexpensive and easy to maintain. It is translucent, which provides a semi-diffused light, and retains heat well, especially when double-walled.
Polyethylene films only last 3 — 5 years in outdoor conditions, and are subject to stretching and sagging in windy locations or after being loaded with snow. This material can be poked through by falling branches, or torn during winds if not well secured. Twin-wall, high-density polyethylene sheets are more flexible than polycarbonate panels, more rigid than polyethylene film, and come in rolls or sheets as covers for greenhouses.
The material is 2-ply, with inner walls which separate the sheets and create an internal air space. This provides excellent insulation value. Twin-wall polyethylene is milky white, or opaque, in appearance. An example of twin-walled polyethylene is the Solexx line of greenhouses. Durable and lightweight, UV-treated polycarbonate is a modern, high-quality covering material for greenhouses. Available in different thicknesses, polycarbonate panels provide the clarity of glass but are not as strong or scratch resistant as tempered glass panels.
Single-walled polycarbonate lacks the heat retention and strength of multiwalled polycarbonates, and single-wall polycarbonate provides no light diffusion. Polycarbonate coverings have a relatively long lifespan of 15 years or longer in most regions. Multiple-walled polycarbonate greenhouse coverings are very popular because they have internal air spaces which provide added strength and excellent insulating values. Of particular importance, multiwalled polycarbonates provide diffused light.
This covering has all the benefits of twin-walled polycarbonate, but superior strength and heat retention qualities. It is especially useful in cold climates for year-round indoor gardening. Triple-wall polycarbonate will withstand heavy snow loads and freezing without cracking or becoming distorted.
Insulation values of polycarbonate greenhouse glazing — The image to the right above shows the construction and relative thickness of available multi-panel polycarbonate glazing used for greenhouse cover panels. Note: The vertical separators have three functions: they add structural strength to the panel, increase insulation value by providing an air space, and serve to break up, or diffuse, the light passing through the panels.
A greenhouse frame provides structural integrity and serves to anchor the greenhouse covering. Greenhouse frames are available in a variety of materials. Aluminum provides a strong, lightweight frame that will not rust. It is the most widely used material for greenhouse frames, and it has a very long life span.
Aluminum frames commonly have extruded channels which provide a perfect fit for inserted covering panels. Aluminum is not an insulative material, so there will be some heat loss through the framing. Powder-coated aluminum retains a smooth outer finish as well as providing different colors. Galvanized steel frames, usually tubular, are extremely strong, long lasting, and low cost.
Polyethylene film is often used for covering steel framing because other covering materials require fastening systems which do not lend themselves to steel frameworks.
Steel frames are heavy, which helps the greenhouse remain stable in windy conditions, but the weight makes transporting and assembling the greenhouse more difficult. Steel is usually used for large commercial greenhouses. Plastic frames have become popular because they are attractive, less expensive than aluminum and do not conduct heat out of the greenhouse as much as steel or aluminum. Plastic frames lack the strength of metal frames, so they are used primarily for smaller greenhouses which have shorter dimensions.
Plastic frames are often designed to be used with polycarbonate panels. Wood greenhouse frames are often used in do-it-yourself greenhouse building projects. Wood can provide an aesthetically pleasing appearance and sufficient strength and durability.
However, wood is susceptible to rot, so the construction should ensure that the wood does not contact the ground or any moisture holding surfaces. When you purchase a greenhouse, take into consideration what accessories are included in the purchase price.
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