Greenhouse Buying Guide

If you are a keen gardener or looking to flex your green fingers for the first time, a high quality greenhouse is an essential garden purchase. A greenhouse can extend your growing season, providing you with the optimum conditions in which to nurture your own vegetables, fruits and plants.

So, which is the best greenhouse for you? Follow our guide to learn more…

This guide will cover the topics below. Click a topic to go straight to the information you need.


Greenhouse Decision 1: Design and Size

Greenhouse Decision 2: Frame Material

Greenhouse Decision 3: Glazing

Greenhouse Decision 4: Doors

Greenhouse Decision 5: Vents

Greenhouse Decision 6: Staging

Greehouse Bases

Greenhouse Installation

Greenhouse Delivery

Our Customer Service Team



Greenhouse Decision 1: Design and Size


Greenhouses come in a wide range of designs and sizes to suit your garden and the growing capacity you require.

Mini Greenhouses


These tend to be lean-to greenhouses or freestanding half height greenhouses that provide growing room for those with small gardens or even balconies. These small greenhouses are also ideal for those just starting their journey into grow your own gardening.


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Mid-sized Greenhouses


Mid-sized greenhouses: 6x4 and 6x8 greenhouses are the most popular sizes for the average gardener who enjoys growing tomatoes, peppers and cucumbers or who enjoys growing from seeds and plug plants before transplanting them out to their garden borders.


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Expansive Greenhouses


10x12, 8x20 and 10x20 are just a few of our largest greenhouses. They offer the professional grower or keen horticulturalist plenty of space for growing and overwintering. These large greenhouses even have enough room for garden furniture.


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Lean-To Greenhouses


Lean-to greenhouses are designed to make the most of your available garden space by sitting against another object, such as a fence or wall. They usually come with a pent roof, which gradually slopes downwards, from a high point at the back of the greenhouse.


Lean-to greenhouses are far more versatile than you might think. Those with a back panel can be positioned anywhere in the garden, while larger models are often suitable for use as conservatories too.


What size is best for your space?


Of course, you will be guided by what room you have available in your garden.


As a greenhouse relies on sunshine, you will want to choose an area which receives the majority of sun over the day. Remember you will need space around the greenhouse for light and for maintenance.


Beware! Growing can be addictive so, before long, you’ll be wanting more room.

Top Tip: Check the precise measurements in the specification


Not all 6x4 greenhouses are exactly 6x4. The same goes for all other sizes. These are just approximate measurements that act as a general starting point.


ALWAYS check the specification guide on each product page for precise, detailed measurements. Our friendly UK-based call centre will be happy to answer any queries you may have.


Greenhouse Decision 2: Frame Material


Aluminium frame


The vast majority of greenhouses have aluminium frames. Aluminium is a strong metal which is also rust resistant, so very low maintenance. Aluminium frames will often have with a powder-coated finish. Many aluminium greenhouses have integral gutters as part of the so you can connect your own water butt.


Look out for extra framing on the larger models.


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Wooden frame


Wooden frame greenhouses are a beautiful garden feature in their own right. The natural timbers make them a superb choice for blending into your garden.


Look out for pressure treatment and 15 year guarantees as this will mean you won’t have to treat the greenhouse for over a decade – leaving you more time to enjoy nurturing your plants. A dip-treated greenhouse will need annual treatment.


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You do have a choice when it comes to the colour of your greenhouse. Aluminium frames can come in their natural silvery metal or with a powder-coated finish in traditional green, modern grey, or striking black.


Wooden greenhouses can be painted or stained in a whole host of colours. This will take time, due to all the glazing to avoid, but can produce a striking result.


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Greenhouse Decision 3: Glazing


Toughened glass


Because standard horticultural glass is only 3mm and shatters into sharp shards, most manufacturers will offer an upgrade to toughened glass. Toughened glass or safety glass is designed to break into larger, safer pieces.


Offering the highest light transmission, glass lets through around 90% of light which supports your plants’ growth. It is direct light, rather than diffused or scattered. This is helpful for regions that tend to have lower temperatures even in the height of summer. Be aware that – for most regions - shading will be essential.


Glass greenhouses are not as well insulated as polycarbonate ones as they heat up and cool down quickly. You will require a greenhouse heater as well as shading. Also, glass requires regular cleaning throughout the year. However, as long as it is not broken, durable glazing can last forever.

Polycarbonate panels


Polycarbonate is the most common form of greenhouse glazing. It is a specialist form of plastic which, when used in a greenhouse, is UV protected to prevent it from yellowing or becoming brittle. The superior brands of polycarbonate will also break down harmful UV rays to protect you and your plants.


Another benefit of polycarbonate is that, as a light material without sharp edges, it is easier, safer and quicker to install. Though it is prone to scratching, it only needs cleaning one or twice a year so is a much lower maintenance option than glass.


Polycarbonate diffuses the light. Clear panels will diffuse light less than frosted panels and are best for germinating seeds and nurturing any plants you later want to move outside. Clear panels also provide views of your garden while you are working inside.

Frosted Polycarbonate panels


Frosted or opaque polycarbonate diffuses the light even further than clear polycarbonate. It is better for growing taller plants and vegetables you want to mature inside the greenhouse. The more diffused light will result in plants that aren’t so “leggy” having stretched to find the hot spots of direct light. Diffused light wraps around plants and reaches lower leaves as well as top leaves.


Polycarbonate naturally retains more heat than glass as glass is very quick to heat up and cool down. Look out for twin-wall polycarbonate as this provides the best insulation in the winter. The twin-wall design creates a buffer of air pockets between the glazing that decreases heat loss.


Be aware that standard polycarbonate only has a life span of around 10-12 years. Also consider a hybrid greenhouse which combines frosted and clear panels.


Greenhouse Decision 4: Doors


Single or double doors


This decision can be pre-determined for you based on size. However, if you do have a choice consider what you will be moving in and out. Are you likely to have large flower pots? Tall plants? Need to get a wheelbarrow in and out? Bear in mind that double doors may take up “wall” space.




Though greenhouses do not often contain highly valuable contents, you may – especially if your greenhouse is on an allotment – want to be able to secure your greenhouse door. This is usually done via a padlock through the holes of the handle though some models do come with a key-operated lock.

Sliding doors


Some gardeners prefer a sliding door as it won’t swing open in winds and is a space saving feature.


Look out for zero-threshold doors. These have no bar across the bottom, making it easier to manoeuvre items in and out and giving you one less thing to trip over.


Shop single door greenhouses


Shop double door greenhouses


Greenhouse Decision 5: Vents

Vents (roof windows) are important in your greenhouse for regulating temperature and creating the optimum growing conditions for your plants. Good ventilation is important in combating fungal diseases. A greenhouse should have at least one roof vent. The larger the greenhouse, the more vents you will want.

Look out for models with a louvre panel. This allows for fresh air to be drawn in at the bottom which will then rise and be released as hot air through the roof vent. Having vents on different levels maximises air flow and circulation throughout the greenhouse.


Look out for models which come with an auto-vent. This will gauge the temperature and open the vent once the heat increases. Autovents can either have electric motors (some of which can be programmed) or use the expansion and shrinkage of a heat sensitive material, such as wax, to move the piston. 


Greenhouse Decision 6: Staging


Staging is the term for work space in a greenhouse or shed. Full width benching or a potting table is essential for potting up, planting seeds trays etc.


Shelving can also provide space for storing plants. Individual shelf sections allow you to leave space for tall plants.


Look out for seed tray stands which maximise space by offering tiers of storage for your seed trays.


Greenhouse Bases


There are a variety of options for greenhouse bases. Whichever you choose, you must ensure the base is level and solid.

Plastic Bases


A plastic base comes in kit form consisting of a membrane and interlocking squares. For larger greenhouses, it requires pea gravel to fill the squares. The greenhouse will then sit on the plastic squares. Using a plastic base does not require a concrete surface and it can be placed straight onto a prepared, level grass area.



Full Concrete Bases


You can use poured concrete or concrete slabs to create a solid, flat base for your greenhouse – or you may have an existing level patio. If using concrete slabs, you can use shingle between slabs to space out the slabs which may be cheaper than buying a larger number of slabs. The shingle may also help drainage after watering plants.

Perimeter Bases


You can use slabs or bricks to create a perimeter base. A line of slabs or section of bricks is then placed down the middle of the interior as a pathway. This leaves direct access to soil for growing inside the greenhouse. You can choose to leave as much or as little soil exposed, as long as the perimeter is stable and unlikely to shift.


Greenhouse Installation


A few of our larger Forest Wooden Greenhouses offer an installation service. Though not all providing installation services at this time, all our greenhouse manufacturers provide comprehensive assembly instructions and customer support lines.



Greenhouse Delivery


How soon will delivery be available?


Many of our products are available on pick-a-day delivery. This means you will be able to select your delivery day before you purchase. This will be shown on the product page if available.


If pick-a-day is not available, look for lead times on individual products as these will tell you when a product will be available for dispatch. You will then be contacted by the manufacturer who will arrange a delivery date with you.


If you make any changes to your order once paid for, this can change your delivery date. Therefore, please check you have ordered everything you need.

What are the delivery charges?


Many of our products include free delivery. However, some more remote postcodes do incur delivery surcharges even where free delivery is available to others. Use the postcode checker to ensure we deliver to your area and to identify any possible surcharges.


Our Customer Service Team

If you have any other questions or require any clarification on any of the information above, please call our friendly, knowledgeable, UK-based Customer Service Team. We are always happy to help.