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Congratulations, you’re taking the exciting next step in your gardening journey and you’re looking to buy yourself a greenhouse!
We have here outlined some of the key things to be considered when first entering into the greenhouse market.
You’ll want to think carefully about how your greenhouse will best fulfil your greenhouse goals.
Is it all about the plants, making sure you have the best possible growing environment?
Is the look of the greenhouse important to you?
Or is engineering your key point of concern?
Once you have considered the answers to these questions, you will be on the way to finding your dream glasshouse.
In this guide, we will go over the following considerations for buying your greenhouse:
- Base Options
- Location & Environment
- Ventilation & Shading
- Water Collection
“How big?” is always the first question to consider when looking to purchase a greenhouse. Answering this question will help give you an indication of many further considerations: physical limitations, budget and gardening plans.
How much ground space do you have in your garden? Physical limitations are obviously going to be key. And it’s important to remember that a perimeter is needed too, so take this into account when taking your measurements.
How tall do you want your greenhouse to be? Are you planning to grow fruit trees inside or just potted succulents? You may require greater height if it’s the former. And if you are going to spend a lot of time there, you will probably want a greenhouse you can stand up straight in, so consider your own height when looking at the eave and ridge measurements.
If you’re squeezing in a larger greenhouse into a small space, other space-savers should be considered, such as sliding doors rather than swing-doors. Or perhaps a lean-to greenhouse would serve you better, than a free-standing greenhouse as it can be snuggly placed alongside a fence or wall.
1a. Small Greenhouses
If you’re really limited by space, consider getting an urban or patio greenhouse. These smaller glasshouses are ideal for those with small gardens, balconies and gardening novices looking to expand their horizons.
If you are going small, think vertical and go for a model with taller eaves that will allow you to hang things from above, perhaps get an extra shelf in higher up. And never underestimate the advantage of being able to stand up straight inside if you plan on spending any length of time inside your glasshouse.
1b. Large Greenhouses
If, on the other hand, if you have plenty of space available, always take the opportunity to go bigger than you think you’ll need. The main complaint new greenhouse owners have is that they wished they’d gone bigger. Once you get the greenhouse bug, you’ll be sowing and growing more than you ever thought you could.
And there are opportunities to further customise when you have more space:
- Double Doors
- Doors at both ends for easier access
- A Partition that can allow you to use either end for different purposes
- Staging Options – Free Standing Staging as an island in the centre, as well as wide integral or free-standing staging down the sides
If you plan to use your greenhouse for a pleasant seating area, you will want to be sure you’ve got enough head room and floorspace for milling about and hosting garden parties – even when it’s cold outside, a greenhouse can make for a charming alfresco venue.
2. Base options:
Deciding what kind of base you want to go for is a choice made early on in the buying process, and will determine how much labour goes into the installation process.
Most common options:
As a general rule, metal bases are considered to be easier to install and more reliable long term. Brick bases and dwarf walls require a lot of labour and precision at the time of installation, but some choose to take this option for aesthetic reasons – or when a metal alternative isn’t available, it is perfectly serviceable.
2a. Metal Base Options
2ai. Integral Base
This is by far the easiest option, as it does not require any further building or construction, as it forms part of the frame itself. The greenhouse can be set straight down onto a level, solid surface and secured into place. No mess, no fuss, job done.
The other benefit of an integral base is that it adds structural integrity to the entirety of the greenhouse.
Integral bases are less common, but when found can often be relied on as an indicator of quality and strength.
This is a common option, as the majority of metal greenhouses do not have an integral base. A separate base is therefore purchased that fits the exact specifications of the greenhouse. This is generally assembled separately and anchored in place before the greenhouse itself can be mounted.
This is still an easier option compared with brick bases, as all the measurements have been taken care of.
2b. Brick Base Options
2bi. Brick Plinth
If you don’t have a metal base, you will need a brick plinth to lift the frame off the ground and to anchor the greenhouse into position. You’ll need to build a level plinth to the exact measurements required so the frame can be mounted on top, with the lip of the frame sitting down over the top.
2bii. Dwarf Wall
There are those who prefer a brick dwarf wall for aesthetic reasons. A dwarf wall is a striking visual choice on a greenhouse – not the same as a brick plinth that is only for the purpose of levelling and securing a greenhouse into position. It more nearly resembles a traditional style of greenhouse and can be suited to more rustic locations and premises.
If you do wish to go for a dwarf wall, consider this carefully as it will have knock-on effects for building the rest of your greenhouse if the measurements aren’t perfect. You’ll need what is called a ‘Drop Door’ as well, which isn’t available on every greenhouse You may also find that irregular subsidence and shifting of the ground beneath can cause structural issues in the future.
3. Location & Environment:
3a. Weather & Climate
Do you live in an exposed area? Whether that be an open field, on the coast or up on a hill. Wind resistance is important if the answer is yes.
If you live in a coastal area, the salty air is also more likely to be corrosive to the frame, so think about protecting it with a powder-coat finish.
Are you in a very hot or cold place? Consider getting more ventilation if you live somewhere hot – although it is worth noting, that no matter where you live, it is always beneficial to have more ventilation rather than less. Temperature control is key for greenhouse gardening, so giving yourself the ability to ventilate more (or less) is invaluable.
3b. Siting your greenhouse
- Avoid Sloping Ground
- Keep Away From Overhanging Trees
- Maintain a Clear Perimeter
- Preparing the Ground
- Convenient Location
There is a saying that goes, “East to West is Best”, meaning that the ridge of your greenhouse should align east-west. The reason for this is getting the most sunshine in the winter. But this shouldn’t be considered essential for a domestic glasshouse, as there is generally less difference in the length and width than in a large commercial greenhouse.
If you are in a location that gets a strong prevailing wind, then it is best that the gable end of the greenhouse be facing the wind, as this is the strongest part of the greenhouse structure.
You need a level foundation on which to build, otherwise you’ll have no end of trouble when assembling and it will undermine the structural integrity. Moreover, it is best to avoid siting your greenhouse at the bottom of a slope, because you are likely to get more water collecting underneath, which can result in a waterlogged greenhouse and shifting soil beneath.
The reason for this is quite straightforward – whatever falls down is going to land straight on your greenhouse. So whether that’s the general detritus of leaves and guano, that will dirty the glass; or if there’s a storm that brings down a branch (or the whole tree), it could cause considerable damage.
When building the glasshouse, you need a good amount of space around the area so you can easily access every side. This space will also be beneficial in the years to come, when you want to access all sides for cleaning and seeing to any external issues. Keeping it away from walls and fences will also help to let in more light and help with airflow to louvre vents down low.
When doing the groundwork in preparation for installing a greenhouse, you need to ensure you are creating the most stable position for your greenhouse.
- Compacted Soil
- Hard Standing
Few greenhouses can be placed directly onto compacted soil, because to do so requires greater structural integrity than can be offered by cheaper brands.
Regardless, if the greenhouse can be placed onto soil, it must be firm and level and not prone to shifting. Consider the type of soil you have and take care to avoid placing your greenhouse on very wet or very sandy soil that could get waterlogged or move easily. A good level of loam is ideal.
The greenhouse will still need to be anchored into place, but this is easily achieved with a few anchors concreted into place.
If you are siting directly onto soil, you may well be wanting to use the ground area inside the greenhouse for growing. If this is the case, make sure that the top layer of compost is good quality.
Firm and level is all that is required here – concrete, paving slabs on cement, brick patio. The base of the greenhouse can then be drilled directly into place.
NB: Avoid gravel or shale when installing. It is very difficult to secure your greenhouse onto these surfaces, but should you wish to lay gravel after installation, you may do so.
It might sound obvious, but when deciding on where to site your greenhouse, make sure it is somewhere that will be convenient for you. Perhaps keeping it closer to the house so you don’t have to run far in pouring rain, or keeping it close to the shed so you don’t need to carry your tools too far.
Most modern greenhouses are aluminium, while traditional greenhouses were wooden.
When considering a long-term purchase, you will get far more years out of a metal frame – that cannot be disputed.
In order to both protect the frame and add some visual flare to your greenhouse, you should consider getting it power-coated or painted. This can be done on both timber and aluminium frames and will greatly improve the outward appearance of your greenhouse.
Generally speaking, there are 3 options when it comes to glazing your greenhouse:
- Horticultural Glass
- Toughened Safety Glass
We would always recommend going for the Toughed Safety Glass, for a number of reasons:
Firstly, as the name would suggest, it’s the strongest option. If you’ve got children playing football in the garden, or pets running rampant, the insurance of toughened glass is the best in terms of safety. It can take a beating in the first instance, and when it does break, it shatters into tiny fragments that are much safer to clear away and less likely to cause injury. When Horticultural glass breaks, you are likely to get large jagged shards that could easily cause harm.
Horticultural glass is what most greenhouses will have as standard included in the price.
The Polycarbonate option is often more expensive than getting Toughened Glass.
Stronger greenhouses are designed with Toughened Glass as standard – which is reflected in the price of the greenhouse (i.e. you pay more for the quality). However, because the Toughened Glass is less likely to break, you’ll be spending less money on replacement glass if and when you might need to – even Toughened Safety Glass isn’t invincible.
So, you are economically better off in the long run regardless.
It will better withstand changeable weather conditions – storms and strong winds. If you go for polycarbonate, the light-weight panels can be billowed out and shifted by the wind. You could well be chasing the panels around your garden, or even watching them fly off beyond the garden fence doing who knows what damage.
It is important to keep your greenhouse clean. If you let it get dirty, you won’t be getting enough light in and your plants will suffer. And the dirtier it is, the easier it is for pests and diseases to lurk in the crevices and spread.
So, you should be regularly cleaning the entire structure – at least once a year. This is easiest during the colder months when the greenhouse is emptier, and you’ll want to do it before the growing season starts to get the full advantage of a sun-filled glasshouse.
For that reason, it is important to consider the practicality of cleaning your greenhouse when you are selecting the glazing.
Polycarbonate is difficult to clean. The corrugated plastic and the twin layers have lots of nooks and crannies for grime to get into. And because the panels are liable to shifting and flexing, getting enough pressure into the grooves isn’t easy either.
Horticultural glass is reasonably easy to clean, but because the panes are easier to break, you’ll need to take care when leaning on the glass. Horticultural panes also tend to be smaller in size than Toughened Safety Glass, meaning that multiple panes can be overlapped with each other to cover the area. Again, this will gather grime that is difficult to clean away.
Toughened glass is the easiest to clean – both in terms of safety and practicality. No nasty grooves for dirt to get stuck in and sturdy enough to take a thorough scrub down.
The are two main fittings, when it comes to greenhouse glazing:
- W-Clips/Spring Clips
- Glazing Beads
W-Clips (also known as Spring Clips) are the most common and are so-called because of their shape. They hook underneath the flange of the struts and then press down over the glass to hold it in place; secured at intervals along each side of the pane. They are relatively easy to fit, but are quite flimsy and can pop out easily.
They are not going to offer a great amount of security, so is not recommended for anyone in an exposed area that might experience high winds.
Glazing Beads are long strips of rubberized material that go the full length of the pane of glass. They are designed to fit tightly between the pane of glass and the greenhouse frame.
They take a bit of effort to install, because of the snug fit. But this additional effort when installing is proportional to the strength and sturdiness of the glazing once secured. The beads hug around the panes and take a great deal of pressure, compared to the Spring Clips that can buckle easily.
Glazing beads are undoubtedly better for strength of the frame, and the security provides safety long-term.
STRENGTH IS KING
The stronger the structure as whole, the better, is the simple answer to all of the above. Having a secure frame and glazing method will enhance the overall durability of the glasshouse and give you a plethora of further options to later customize, should you so wish.
5. Ventilation and Shading
No matter what you’re growing, you need to be careful of overheating. Scorched plant leaves and soil as dry as sand is never ideal, so ensuring you have the option to ventilate more is always advisable.
It is best to have a combination of roof vents and side louvre vents, as it allows for air to circulate. This will help control temperature and help prevent the spread of pests and diseases.
Automatic vents are a great way to take the stress out of greenhouse gardening. Solar-powered wax cylinders are used in all Rhino greenhouse roof vents: - They warm gently as the sun shines down; the wax expands and contracts, gently opening and closing the vents.
Shading is a great way to further control the temperature inside your greenhouse. The easiest way to do this is with fitted blinds that can be easily pulled down as and when necessary. Alternatives exist – shading paint that can be applied directly to the glass and washed off later or breathable fabric can be hung around the interior – but fitted blinds will remove the faff from the process.
6. Water Collection:
Would you like to collect your own rainwater? If so, you’ll want some gutters and downpipes on your greenhouse. Some greenhouses come with these are standard and you can easily add a water butt or other container to start collecting that delicious H2O as soon as the greenhouse is installed.
It will be essential for wheel-chair users to ensure that their greenhouse has a low-threshold entrance. This will allow wheels to roll smoothly in and out – and is also great for coming and going with a wheelbarrow. It may also be worth considering a greenhouse with double doors, to allow for easier access.
Want to grow your own sumptuous greenhouse tomatoes?
A Rhino Greenhouse is the perfect environment for all your plants.