First-time Buyer? 10 Things To Consider

In the last decade, greenhouses have become enormously popular in Ireland. Not only do they allow you to nurture shoots and seeds, cultivate exotic plants and flowers, and grow organic fruits and vegetables, but they also provide you with a tranquil space to relax in your garden. For anyone thinking of buying a greenhouse, the benefits are plain and simple. But for anyone starting out on their greenhouse journey, finding the right greenhouse is much more difficult. We have prepared a greenhouse guide to help first-time buyers to ask the right questions before they buy. 

Greenhouse sales on the up

Why you need a guide

Type “Irish greenhouses” into Google and you will find a long list of suppliers offering you hundreds of different models of varying price and quality – from the cheap and flimsy to the strong and overpriced. Not only that, but there are so many other variables to consider. Do you want a wooden or aluminium frame? Polycarbonate or toughened glass? Free-standing or lean-to?  For both novice and experienced gardeners alike, buying a greenhouse can be confusing. 

Below are ten things to think about before you buy. 

1. Site

Take your time to choose a site because it will impact on all of your subsequent decisions.  You should choose a site that is both firm and flat. Make sure you leave enough space on the sides to allow you to clean the exterior panels. Avoid positioning your greenhouse under trees or overhanging branches, and make sure you have easy access to your water and, if necessary, electricity supply.

Choose a site carefully

Above all, choose a site which receives ample sunlight. Even a state-of-the-art greenhouse won’t generate enough heat if it’s hidden in the shade. Some experts recommend facing the side of your greenhouse southwards. This is good advice if the length of your greenhouse is significantly greater than the width. But it’s not essential if you have, say, a 6 x 8 foot model. 

2. Size

The most common advice you will hear when buying a greenhouse is “buy the biggest greenhouse you can accommodate”. That this cliche probably originated with greenhouse salesmen shouldn’t put you off. Space is genuinely important – after sunlight, it’s your most important asset. Within a couple of seasons, you’ll be wishing you had some extra space to squeeze in an extra row of tomatoes.

Lastly, make sure your greenhouse has enough headroom under which you can work. Many cheaper greenhouses are built with a low eaves in order to keep costs down. If you intend to spend long periods in your greenhouse, you don’t want to end up stooping.

Small 8×8 Greenhouse

3. Style

Greenhouses come in many different shapes and sizes. Most domestic greenhouses are rectangular with a pitched roof. But you can also find hexagonal, octagonal, dome-shaped, and semi cylindrical models. You can also build customised greenhouses which are considerably more expensive than standardised models. For example, you can attach a lean-to greenhouses to the exterior wall of your house, or you can fix a greenhouse frame onto a customised dwarf-wall for aesthetic effect.   

Traditional pitched roof greenhouse

In Ireland, traditional pitched roof greenhouses are by far the most popular style. Not only do they look good but they can be positioned to maximise their exposure to to sun. In winter, their rigid structure stands firm against heavy rainfall and windstorms. 

4. Frame

The frame of a greenhouse is generally built from wood or aluminium.

Wooden frames are impressively sturdy and their soft organic features blend naturally into the greenery of any garden.  But they are expensive, require maintenance, and rot if not carefully protected. 

Aluminium greenhouse are strong, require little maintenance, and if powder-coated, they will last for up to twenty five years. They generally sell for a quarter of the price of their wooden counterparts and come in a wide range of colours that will suit almost any garden.

But be careful. Avoid aluminium framed that look flimsy or weak. A good quality aluminium frame has sufficiently thick posts and joints, as well as cantilever supports. 

Cantilever supports for roof and staging

5. Glazing

Greenhouse glazing is made from polycarbonate, horticulture glass or toughened glass. 

Horticultural glass is an old-fashioned glass which captures a wider frequency of light than polycarbonate or toughened glass.  It’s the cheapest glass you can buy, but it may cost you more in the long run because the panels often break and need to be replaced. When the glass breaks, it cracks into large jagged shards which is particularly dangerous if you have children or pets in your garden. 

Toughened glass is a modern alternative to horticultural glass. It admits almost as much light, but it’s five times as strong and significantly heavier. Unlike polycarbonate, the panels won’t blow away in heavy wind, and the extra weight helps to reinforce to the greenhouse frame. It’s much safer than horticultural glass and can withstand the full force of a leather football without breaking. In the rare event that it does break, the panels shatter instantly into thousands of tiny pieces. At worst, you will end up with a minor scratch. 

Polycarbonate glazing is a material not dissimilar to plastic. It is cheap, safe, and good for insulation.  But polycarbonate greenhouses admit less sunlight than glass and they often blow away in heavy wind. The translucent glazing is noticeably synthetic and you may  find it looks out of place in the organic surroundings of your garden. 

If you are looking for glazing that is strong, elegant, and safe, toughened glass with a bar capping system is your best option. 

6. Clips or Bar capping

Once you choose your glazing, you must decide how to secure the panels to the greenhouse frame. On cheaper greenhouses, the panels are usually held in place by metal clips.  But these clips are fragile and should be avoided if your greenhouse is on a site that is exposed to strong winds. If you are looking for a more durable option, look for a greenhouse where the glass panels are held in place by bar capping.  Not only will it firmly secure the glazing, it will also add extra insulation and reinforce the greenhouse frame. 

7. Extra Features

A greenhouse is more than a roof and four walls. You need to equip it with the tools to help you make the most of your garden.

Most suppliers offer louvre windows, roof ventilators, automatic openers, staging, gutters, downpipes, and sunshades. But be careful. These extra features are not included in the initial asking price – and like hidden airline fees, they quickly add up. 

To novice gardeners, some of these features may seem unnecessary. But anyone serious about greenhouses knows they crucial. In particular, it is essential to have enough ventilation to allow you control the temperature of your greenhouse in hot weather.

automatic roof vents

8. Foundations

Like all buildings, a greenhouse is only as strong as the foundation on which it’s built. Greenhouse foundations are usually made of bricks, flagstones or concrete into which the greenhouse is firmly bolted.  They will stop your greenhouse warping and protect it from blowing over in stormy weather. Without one, your greenhouse simply will not last. 

Before you lay the foundation, make sure the ground is firm and level. If you are laying a cement foundation leave room in the middle to grow plants and drain water.  If you are laying bricks, consider using mortar to reinforce the brickwork. 

Concrete Foundation

9. Delivery & Installation

Most greenhouses in Ireland are imported from the UK and it usually takes six weeks for delivery.

It can be complicated and time consuming to install a greenhouse by yourself.  So if you’re not handy with a set of tools consider hiring a professional. Most greenhouse companies will provide provide installation services for a fee.

10. Price & conclusion 

There’s an old joke where a man walks into a specialist wine shop and says: “Can you recommend me a cheap bottle of red?”. The owner replies: “How much do you want to spend? Cheap could mean £15 or £150 – and I don’t want to offend.” 

Like wine, how much you spend on a greenhouse depends on what you’re looking for – and, to a large extent, your budget. But there are a few things that are important to remember. 

A cheap greenhouse won’t last more than a few seasons – some may even blow down in the first windstorm. On the other hand, a well-built greenhouse will last perhaps as long as twenty five years. 

Remember that most gardeners acquire expertise over the years so the longer you have one the more you will want from it. Think of the greenhouse you will want five years from now. 

Beyond that, the hallmarks of all longstanding greenhouse are the same: broad aluminium posts, toughened glass, powder coated aluminium, cantilever supports, cement base. 





The summer has been generally good so far.  The vegetable garden has flourished and the flowers have been marvellous. The only thing that has not done so well was the rhubarb.

Last year, I bought a GridGrow mat at Bloom in the Park  to grow strawberries.  The mat suppresses weeds which makes managing the crop much easier than usual. It also keeps ripe strawberries away from the soil. The mat helped me to stop runners taking root, and it allowed the plants to grow strong and well-established.

Strawberries growing on gridgrow and hand picked in bolwsMany greenhouse plants flourish in July – as long as you need to water them every day.  Dampen down the floor in the mornings to humidify the greenhouse.  

It is important to feed tomatoes, peppers, and cucumbers every week. I use a liquid tomato food to feed all three.  Be sure to water tomatoes evenly or they may start to crack or split. If the temperature fluctuates too much, they can also develop Blossom Rot (dark blotches on the ends).

Ventilation is very important in warm weather. Circulate the air in your greenhouse by opening the louvre windows as well as the front door.  The louvre windows draw in cool air near the ground and it escapes through the roof ventilators. 

Check for greenhouse pests too. Use sticky card traps to get an idea of  what pests may be about.  If a particular pest keeps landing on the sticky cards, you can look for ways to treat your plants. Be sure to keep your greenhouse clean of fallen leaves and spent compost.  This can prevent potential pest and disease problems.

For anyone growing grapevines, surplus shoots on a grapevine should be removed weekly to restrict the size of plant.  This will direct its effort in ripening the grapes.  If there are too many bunches of fruit none of them may ripen, so you should remove some of them.  Thin to 10 bunches per square metre of floor space.  This allows more space for the fruit to develop.  

Ventilating Your Greenhouse In June

June 21st is the longest day of the year, and temperatures can raise considerably.  Here are some greenhouse ventilation tips to get you through the summer months. 

Make sure there is enough ventilation in the greenhouse by opening the door, louvre windows, and roof vents.  If your greenhouse gets too hot, your plants may scorch. All Landmark Greenhouses roof vents open automatically once the greenhouse reaches a certain temperature.  This is particularly useful if you are away during the day.   The louvre windows draw in cool air at the base of the greenhouse it circulates around the greenhouse. The rising warm air escapes through the roof vents. Landmark Greenhouses roof vents open automatically once the temperature reaches a certain level.Louvres draw in air at the base of the greenhouse, which ensures better air circulation and growing conditions.

Other Cooling Tips

There are other strategies you can use to keep your greenhouse cool. If you are forecasting a hot day, dampen down the floor of your greenhouse. In extremely hot weather, you should do it twice a day – but never in middle of day because you may scorch the plants. At Landmark Greenhouses we damp down with rainwater collected from the gutters and downpipes. You can also hang netting from roof of your greenhouse. It protects them from direct sunlight. If you use this method, remember not to shade your tomatoes. There is also a screening wash that can be applied to outside of greenhouse and washed off in the autumn. Check all greenhouse plants regularly for aphids, red spider mite, mealy bug ad scale insects as these pests can increase greatly in numbers in warm weather.

Kathryn Sheehy 5 days ago

Here is a lovely review from a recent customer Kathryn Sheehy:

“My husband purchased a 10×16 foot greenhouse in 2018, so this is our second season with a Landmark greenhouse. We are delighted with both the product and the advice from Tony before and after purchase. We particularly happy with the extra features: staging, louvres, auto-vents, powder coating, 4mm toughened glass, and double doors supplied at no extra cost”.

“We live in Kerry about 2km from the sea and are subject to very severe south-westerly winds. So far the greenhouse has withstood the efforts of several storms – most recently Storm Hannah which decimated our apple crop for the year. My husband spent the entire winter researching greenhouse brands before deciding on Landmark. It’s the best available both in quality and price”.

“The advice we got from other greenhouse owners was to get the biggest we could accommodate. So true. The 6 ft.eaves height (on the 16 x 12 model) and the reinforcement brackets on the roof and eaves are a particular advantage. The staging is also great for growing vegetable and flower seeds prior to planting outside.

“With a greenhouse, you get two months of growing time either side of the season. At present, we have two grapevines, dwarf peach and nectarine, and a fig tree. And we have 15 tomato plants, 4 aubergines and 4 peppers all growing away happily.”

“We couldn’t be happier with the product & service from Landmark”.