Buying a new house is very stressful, as is buying a new car and other expensive items, but over the years we do gain some experience with these major life purchases.
We deposit these experiences in own knowledge bank, ready to withdraw when we buy again. But this is not always the case with buying a greenhouse as many of us may only buy one in a lifetime, therefore we have no experience of a similar purchase.
Buying a greenhouse can be a fairly major purchase financially but also a major purchase in time. Greenhouses need a keeper, what you put in is directly proportional to what you take it, but you have to commit first, and try second. Getting it wrong can hurt.
Should I Choose a Metal or Wooden Greenhouse?
Wood was the traditional choice, in fact, the only real choice, in the middle of the last century. Red Cedar was probably most often used as it was hard enough to be long-lasting, but not close grained enough to be used for furniture.
Timber also has good insulation properties so keeps the greenhouse warmer in the winter and cooler in summer. Often they would feature a low wooden wall that may have kept out some light but retained heat. And of course, wood is very tactile and has a distinctive smell, with many people prefering its appearance and characteristics to any other building material.
So what's not to like? The cost initially, of course, and then the upkeep with the expense of preservatives and ultimately the threat of rot and decay. However, pressure treated timber has a lengthy guarantee against decay and newly introduced ThermoWood with practically all moisture extracted, does not require annual re-treatment and is warp and crack resistant.
Metal is the obvious alternative, in particular extruded aluminium. When designed correctly the bulk of the load bearing goes down the length of the aluminium bars where its strength lies, yet it is very lightweight. These are great properties to pack in a box which can then be relatively easily transported in part form. Aluminium gave birth to the modern greenhouse kit or hobby greenhouse as our American cousins like to term it.
Aluminium does not rust either, which is useful as it will stand out in the rain for many years, and when it doesn't rain we will make sure it gets wet on the inside with our hosepipe or watering can. Aluminium does eventually get a powdery exterior coating and dulls off when it oxidises with the air. Greenhouse manufacturers have found that the solution to this problem is to powder coat the aluminium. The powder coating can be a choice of colours, green is most popular, though black, white, brown and grey all have their supporters.
Another advantage over wood is that aluminium greenhouses can be taken down and moved relatively easily should the need occur. The biggest factor, however, is still probably pricing, as aluminium greenhouses are cheaper to buy than wooden greenhouses. They also tend to have more available accessories.
Once you have made your material choice you need to consider style.
What's The Best Style?
These let light in from all sides, there's plenty of room for staging and they are very practical. This style offers the most growing area. Modern styling has seen elegantly curved glazing introduced and a 'barn' style offers extra height for tall plants. 'Orangery' type constructions are as much about outside leisure as gardening.
Free Standing Circular or Lantern Shaped
These are attractive designs but space inside can be limited. They are most suited to the medium or larger gardens as a feature or a focal point.
Conservatory or Lean-To
Good if you have restricted space but unsuitable for north facing walls and can overheat if south facing. Light levels are less than a freestanding greenhouse so traditionally the back wall has been painted white to return any available light to the plants. The back wall retains heat and can also be used to train and support climbing plants. If there is an internal door, lean-to's are very convenient as essentially you don't need to leave the house. It should also be noted that you can only use toughened glass if there is an internal door leading to the lean-to. Read more about lean-to greenhouses on our 'Buying a Lean-To Greenhouse' blog.
Fixed against a wall and often featuring a series of internal shelves. They are often attractively styled and are are perfect when space is at a premium. You cannot enter most wall gardens so you simply have to lean inside and stretch your arms in. A great way to grow when space and budget are both limited.
What's The Best Position For My Greenhouse?
Do not position the greenhouse:
- Where it will fall into deep shadow of a building
- Under trees (falling leaves will block light and fallen branches will damage the greenhouse)
- In a frost pocket or in a position exposed to cold winds
Do position the greenhouse:
- On a firm well drained site that is easily accessible
- In the sunniest part of the garden with the longest side facing south (although with smaller greenhouses, that are practically square, this isn't important)
- In a sheltered position away from high winds, making sure the door is facing away from the prevailing wind
- If it is a 'lean-to' style, always locate on a south facing wall
- As near as possible to sources of water and electricity (always have a store of water in the greenhouse so you use it at the ambient temperature)
Does The Greenhouse Need A Base?
A pre-formed base is not essential, after obtaining the base dimensions you can construct one. However metal bases come as standard with many greenhouses or can be bought to save you a lot of time and trouble. Any base should be securely attached to a foundation, definitely not soil or turf, this may be slabs or concrete, overlapping the edge of the greenhouse by about 6 inches.
To lay the strongest foundations, you can excavate the ground around the perimeter of the greenhouse to create a strong foundation. Dig out a spades width to a depth of 5-6ins around the edge. Fill the bottom 3-4ins with rubble, hardcore, stones etc. and crush it in. Either add 2-3ins of concrete mix on top, if you want concrete, or add a few more smaller stones, firm down & top with 1ins sand, on to which you can lay slabs (maybe 18ins x 9ins). Alternatively fill all the hole with hardcore, crush in firmly and top with a sprinkling of sand to level it off.
What Are The Different Types Of Glazing?
Greenhouses normally come with two or three glazing options:
Standard Horticultural Glass
- Cheapest option
- Clear glass for maximum light
- Splinters into shards and can therefore be dangerous
- Breaks easily under slight pressure eg when cleaning or fitting
Toughened Safety Glass
- Much stronger than standard
- Disintegrates rather than breaking into shards
- Clear glass for maximum light
- Should conform to all safety standards
- Ultimately the most safe option
- Similar to double glazing, offers better insulation
- Harder to break than standard glass
- Transmits 85% of light with good diffusion
- Cavity between glazing can attract condensation and algae
- Lets in less light
- More vulnerable to wind damage
Does The Greenhouse Need Staging?
It is really useful to have staging and shelving along least one side of the greenhouse, on which to perform a number of tasks and where you can place plants and seedlings nearer the light. Pots and other equipment may be stored underneath.
Is There Sufficient Ventilation?
You must control the temperature in a greenhouse keeping it below 80ºF/27ºC. During the summer this is achieved mainly through ventilation. Always check that there are sufficient roof and side vents, 10sq ft of ventilation for every 50sq ft of ground area. During hot weather louvres near ground level allow in cool air that will then heat up and rise, exiting through top ventilators, thus providing an effective throughput of air. If you are away for any length of time, automatic vernt openers will prove very useful.
Do I Need To Invest In Heating?
Heating will be a deciding factor on the variety of plants you are able to grow and the number of plants that can be kept over winter. Temperature during the winter shouldn't dip much below 7ºC and throughout the year the daily variation shouldn't be more than 10ºC, this can be controlled by a combination of heating, ventilation and insulation. The main types of heating used in a domestic greenhouse are:
- Easy to use, reliable
- Clean, no odour or fumes
- High temperatures can be achieved
- Temperature can be controlled by accurately and cost effectively with a thermostat
- Fan heaters provide uniform heat and good circulation
- Fans can also be used to cool in warmer months
- Professional installation is required to install waterproof cables and sockets
- Propane and butane are easy to use
- High temperatures can be achieved
- Temperature can be controlled by a thermostat
- A spare cylinder must always be available
- May give off harmful fumes
- Causes condensation
- Cheap to buy but running costs may be high
- Temperature control is difficult
- May give off harmful fumes
- Requires frequent re-fuelling and daily maintenance
- Creates humidity and condensation
Solar energy or wind turbines may become a consideration in the future but at the moment they are far too expensive due in part to the poor heat retention qualities of a greenhouse. Spent cooking oil is used occasionally commercially but is messy, smelly and not really suited to small scale production.
What Are The Other Optional Extras?
- Insulating bubble wrap
- Capillary matting for watering
- Blinds or Mesh (internal or external) (essential during a hot summer) or
- Shading (a proprietary mixture that is applied to the glass to protect plants from direct sunlight)
- Water tank (to warm water to the ambient temperature)
- Min / Max thermometer to ensure temperature is accurately measured and can be controlled
- Rainwater collection kit
What Size Greenhouse Should I Choose?
For many of us this decision is already partly made as space in most British gardens is fairly limited, particularly for city dwellers. And cost is also a major factor. For these two reasons the 8ft x 6ft greenhouse and its smaller clones account for nearly 50% of all greenhouses sold by one major manufacturer.
A small or modestly sized greenhouse is so much better than no greenhouse at all and a great place to start a hobby, as your investment in time, space and money is proportionately small. Growing tomatoes, salad crops and flowers can be achieved quite easily providing your expectations are realistic.
The golden rule has to be to buy the biggest greenhouse your space and budget allows, as you always quickly fill the available space, Eight and ten feet wide greenhouses combined with extra length allow you room to develop, 12 feet wide is a semi-professional width, above this and you need to be growing commercially.
Now you have some idea of material and size for your greenhouses you need to choose a manufacturer or brand.
Which Make of Greenhouse Should I Choose?
You may already have a brand in mind, maybe a friend has suggested one, maybe your parents had one? Basing your choice on brand loyalty is not a bad place to start but if you have no brand loyalty or you want to review the options now is the time to take a look.
Halls Greenhouses are possibly the most well-known brand in the UK. They have been available in garden centres, DIY stores and multiple outlets in various guises for many years. When they joined forces with AGL (Aluminium Greenhouses Ltd.) they consolidated their position in the market, particularly in the 6ft wide greenhouse sector. The 8ft x 6ft aluminium model became the optimum size for the burgeoning UK market. They named it the Popular Greenhouse for good reason, as well as a cursory nod to Henry Ford and his production techniques from many years ago. The Halls Popular range expanded to accommodate the 6ft x 6ft version and the 4ft x 6ft version. This baby of the range would prove to be a massive seller and is still so today. The 10ft x 6ft version was the last to be introduced, representing the best value for money in my opinion. I have no hesitation in recommending any of this range.
The Supreme range is based on the Popular sizes but features a curved acrylic window at the eaves. There is no gutter on this model, it is all about style. Halls also sell the 8ft wide range marketed under the Magnum banner. Featuring double doors, extra height, strengthened joints as well as the extra width these offer massive potential at real value for money prices. Halls greenhouses offer lean-to models, mini greenhouses, cold frames and a wide range of spares and accessories. Delivery to UK and Ireland is available as well as a national dealer network to offer the type of service and backup you would expect from such a well known name. Installation is also available from Halls on new purchases in mainland UK.
Elite Greenhouses are a family run British manufacturer of many years' standing. This is enough to get them a seal of approval from many prospective clients but when you dial in the flexibility and innovation that they bring to the greenhouse market you can understand their success. The Hannant family play a large and active role in running the company with Phil directing and his father Richard overseeing. Richard is also a great designer and is responsible for the company's innovative range of Diamond staging and shelving that allow easy access underneath. This is particularly suitable for wheelchairs. The range is large and features the ever popular Belmont range of 8ft wide greenhouses. With standard lengths of up to 20ft available and longer if you want, the Belmont offers extra headroom, doors at either end, a low threshold base, the option to extend plus a full range of accessories. The 10ft wide Supreme and the 12ft wide Classique offer the same options in impressively sized units.
But it's not just big that is beautiful at Elite Greenhouses, take a look at the Elite Streamline range. Solid, compact and functional these 5ft wide greenhouses also feature double doors as standard.
Away from the freestanding range Elite also offer a very extensive range of Lean To greenhouses.Crowned as the Windsor range they are available in 4ft, 6ft and 8ft wide models. One of the great advantages of this range is you can position the doors virtually anywhere, and you can have as many as you need. Choose from an extensive range of powder coated colours or simply choose your own!
Swallow GB Greenhouses
Swallow GB Greenhouses have not been manufacturing for very many years but have already made quite an impact on the UK greenhouse market with their use of ThermoWood, Scandinavian timber that has most of its moisture and resing extracted by heat treatment. This means that the resultant wood does not need treating annually with preservative, as it is highly durable, weather resistant, and will not warp or crack.
They manufacture classic styled freestanding greenhouses, T-shaped structures and lean to's, together with combination and potting sheds. The greenhouses are all wonderfully well designed and built in the UK by craftsmen with ThermoWood used throughout.
Market leading specifications include at least one vent as standard sealed with machined timber capping, toughened glass fitted into a groove with silicone sealing, staging along one side, lockable door, a 20mm damp course along the base and, perhaps most importantly, delivery and installation is included in the price.
The frame can have an opaque acrylic top coat in a standard colour or one of your choice which is bacteria, mould and UV resistant, and there is a long list of accessories including rainwater collection systems and extra staging and shelving.
Eden Greenhouses have always been a perennial standard bearer in the UK greenhouse market. The name and the brand are well known and well respected. Very little changed over the last decade until the autumn of 2014 when the whole range was swept aside. Out went the Acorn, Monarch and Sherbourne to be replaced with a new state of the art range that features the trademarked Zero Threshold range.
Eden consulted with a design company that had previously worked in the Formula 1 motor industry to look at every aspect of design and usability of the humble greenhouse. Having a separate base that ran under the door has been a stable element of aluminium greenhouse design for decades, notwithstanding the introduction of the low threshold base from Elite Greenhouses several years prior. But the revolutionary new design has a ZERO THRESHOLD TM integral base which means no step over for pedestrian, wheelchair or wheelbarrow access. This is a major selling point as it removes a trip hazard in an environment that includes glass, as well as improving ease of access for transporting goods and produce in and out of the greenhouse. The integral nature of the base also adds strength to the overall structure.
Additional height at the eaves has also been built into the new range which is a real bonus for anyone working in a greenhouse that is 6ft tall or over, as I am.
Eden has also looked at the rainwater collecting system and beefed this up considerably with 80mm wide gutters. A strong ridge bar and superior door locking have also been incorporated into the new designs.
The new ranges are available in 4ft, 6ft, 8ft and 10ft wide models with a range of lengths available in each width. The 4ft wide Birdlip range and the 6ft wide Burford range are the most popular as they are designed for the smaller and average size available plot and the amateur gardener. The 8ft wide Blockley and the 10ft wide Bourton are for the more serious gardener that also have space and budget to spend on a high-quality hobby greenhouse.
Vitavia could be short for ‘value for money’ as that is exactly what you get when you purchase a Vitavia Greenhouse. In the current economic climate we all want good value and let’s not be shy here, but many potential customers have a budget. And there is nothing wrong in that as we all choose how we spend our own money.
A comprehensive range means that Vitavia not only accommodates the smaller plot but also offer large greenhouses so savings can be made across the range.
What is also good about Vitavia greenhouses is that the non-painted aluminium frames have a coating that helps reduce the oxidisation of the metal when in the elements. In short they remain shiny and new looking for longer.
The Orion and Saturn models that feature the curved eaves are also supplied with a gutter to collect rainwater which isn’t the case with many other similarly styled greenhouses.
If you are working on a budget and are looking for an everyday hobby or a starter greenhouse then the Vitavia greenhouse range certainly has something to offer you.
The Customer is King
This review is not exhaustive or detailed, but it's designed to be an introduction to help you make the decision that is right for you. Whichever type of greenhouse you choose, whichever retailer you buy from and whichever manufacturer gets your endorsement, if you are not happy, then nobody in the chain can be satisfied. This really should be a purchase where the customer is king!