Category: Polytunnels

Polythene Covers

Today I spoke with a customer. They had been a little confused about Polythene covers. They had seen both a 720 gauge and 800 gauge polythene sheets. At a glance both look identical. Which prompted the question, what are the differences?

There is a lot of options with polythene sheets which can cause confusion. However we recommend for most customers growing a variety of vegetables (or bedding plants and flowers) 800 gauge (200 micron) clear polythene. Most 800 gauge polythene covers give high light transmission which is most important in this country. It also is important that the polythene is ‘thermic’ meaning it is good at reducing heat loss on cold nights. You should always check with your supplier that there polythene has these features. While most of our customers grow organically we need to point out to those who use chemicals that their use around the polytunnels can affect the life of the cover.

At Polydome we give our film a 6 season warranty against UV degradation although it can last longer depending on the amount of sunlight it receives during its lifetime and the laying conditions during installation. A cover tensioning system in our Polydomes Tunnels helps to prolong the cover’s life. Being 800 gauge it is tougher than lighter films which helps protect it in storms and gives longer life than lighter films.

Polydome Blog

Hello All,

Welcome to Polydome’s new blog. We are delighted to be finally online.

Over the coming months we hope to use this source as a means to sharing with you our experience in the greenhouse industry. Over the past 25 years Polydome has become one of the largest suppliers of hobby polytunnels and glasshouses within Ireland. We now hope to pass on some of the knowledge and expertise we have gained over the years. We hope this information will help anyone making the next step in purchasing or making their own greenhouse.

So watch this space.

Irrigation In Polytunnels

The majority of vegetables are 80 to 95 percent water. So next time you look at your lovely vegetables in your tunnel or glasshouse think of them as little sacks of water, flavoured and full of vitamins.

But remember, if the supply of water fails your vegetables yield and quality will suffer rapidly. In the high temperatures found in polytunnels and glasshouses it’s very important to irrigate on a regular basis and guarantee a reliable supply.

The two most common methods of irrigation are overhead irrigation and ground level irrigation. Overhead is by far the simplest method. Water is released from sprinklers suspended from the roof of the tunnel or the glasshouse. These form a mist which saturates everything in the tunnel.

Some draw backs of overhead irrigation: water is wasted as it not only falls on the beds and plants, but also the walkways through your greenhouse as well as work areas: sun spots are more likely to occur as the result of droplets forming on the foliage: and a large number of plants prefer being watered into the root as appose to directly onto the plant itself.

Ground irrigation is a much more effective method. Lines of perforated pipe lay on top of the vegetables beds. Built in regulators in the perforated pipe leak out a set amount of water per hour. This allows even irrigation across the bed and more importantly directly into the root.

However it does have its drawbacks also. More pipes + more fitting = higher costs. Also, as the pipes sit on top of the beds they sometimes can be in the way during weeding and planting.

Don’t forget to automate your irrigation system if you’re away for long periods, therefore guaranteeing that your plants get their daily dose. Tap timers are a simple and effective solution. These can be gotten in many garden centres and DIY shops and are very easy to install.

If you require further information feel free to visit our website.

 

 

 

 

 

The picture on the left is of an overhead spray line. The picture on the right is drip irrigation.

Polytunnels vs. Glasshouses

For those taking the next step and investing in a greenhouse, it can be sometimes hard to find which option suits best. My advice is to find a greenhouse that compliments your garden while also being practical for its intended use.

Firstly you should avoid generalising about characteristics of Polytunnels vs Glasshouses (e.g. thinking Polytunnels are stronger than Glasshouses or Vice Versa).  There are a huge range of Polytunnels from extremely strong to extremely flimsy and the same applies to Glasshouses.  One generalisation one can usually make is that  something very cheap is probably very flimsy, and usually to have something strong is going to cost more that something weak. 

Sometimes customers ask which is better for growing plants – a Polytunnel or a Glasshouse, but if adequate ventilation is provided (and that depends on the features or model you choose) then the growing conditions are much the same.

Ultimately this debate boils down to personal choice, so instead of given my opinion on which I think is best I have listed below some pros and cons of both Polytunnels and Glasshouses. I hope this makes your search that bit easier…..

Polytunnel Pros

If you are looking for something quite large, the difference in cost between a Polytunnel and a Glasshouse is quite substantial.  Vegetables particularly take up a lot of space, so a Polytunnel will give you a larger area of protected space to grow for your money than a Glasshouse – all things in terms of strength and ventilation being equal.

There is more flexibility to customize your structure to suit unusual needs. i.e. widening the doors for machinery or coping with sloping ground, a Polytunnel is much more easily modified than a Glasshouse.

Straight sided tunnels provide a very pleasant working area internally as a result of the height. If your 6’ 2” like me, this is an added plus. It also means taller crops are less likely to be touching off the polythene cover.

Polytunnel Cons

Although Polytunnel Covers are UV stabilised to give long life, they do need to be replaced periodically (depending on the grade chosen usually every 4 or 5 years, but some customers getting much longer – it depends on many factors such as how much sunlight the cover get.   With larger structures this can be a bit of a headache, it requires the customer to think ahead and test the polythene when coming up to its expected end of life so to anticipate when to recover it rather than having the cover fail in the middle of a period of inclement weather.

Polytunnels can prove slightly harder to construct as it involves holding a large sheet of polythene, so any wind at all makes covering tricky. Tensioning the polythene to the adequate tension is a developed skill. It is very achievable by all but takes patience and planning when covering ones tunnel for the first time

In a glasshouse if you break a pane of glass you can replace that pane. Do the same with Polytunnels cover and you have to try and tape it (not the best or most permanent job). In the worse case situation you might even have to recover the full tunnel if needs be.

Prone to attack by cats and dogs (and birds pecking at insects at the ridge). Not the most common of problems however I have heard of it occurring on more than a few occasions. Therefore worth noting if you have pets around.

Polytunnels are not an item of beauty to most, so generally people want to keep them out of sight in the vegetable plot.

At present there are not as many options for ventilation in Hobby Polytunnels as there are for Glasshouses.  Ventilation is usually only supplied by opening doors at both ends whereas a Glasshouse can have roof vents, louvre vents and these can easily be fitted with automatic opening devices which do not need electricity to work.

Glasshouse Pros

 
Glasshouses are available in very attractive designs that compliment a garden, such as Orangeries, Victorian style Models and Dwarf Wall Greenhouses, with the frames being available in a range of colours.  They do not need to be kept out of sight so can be situated nearer your house and this can be an advantage in terms of making use of it.

Glasshouses will need periodic cleaning as do Polytunnels but you don’t need to replace the covers every few years.

Aluminum has a very long lifespan and powder coated models protect the aluminium from oxidising and so retain the good looks of the Greenhouse for longer.

Glasshouses are available with a wider range of ventilation options  than Polytunnels and also there is an abundance of shelving and other accessories for them that are not widely available for Polytunnels.  For example rainwater collection from a Glasshouse is simple as they nearly all have built in gutters, it is just a question of ordering downpipes and a water barrel for it. 

Glasshouse Cons

A flat and level base is required for a Glasshouse, so generally speaking the preparation of the site is a bigger job than a Polytunnel.

The lead time for supplying some Glasshouses can be up to 3 months, so you need to plan ahead  (unless it’s a standard model, these are normally in stock by glasshouse suppliers).  Most Polytunnels that are produced in Ireland can be manufactured within days of order.

To summarise

Joking apart, many customers get both a Polytunnel and a Glasshouse.  The Polytunnel is at home in the vegetable patch out of sight, doing a fantastic job of protecting the vegetables from excess rain and wind, providing excellent growing conditions, the Glasshouse up near the house, a feature in the garden and used for propagation, flowers, bedding plants and perhaps a few tomatoes.  So the question does not have to be Polytunnel or Glasshouse, it can be which Polytunnel and which Glasshouse (probably not all at once).

Grow your own

Grow your own

The difference will amaze you. Free from the ravages of the weather you can create ideal growing conditions for all sorts of vegetables and flowers in a Polytunnel or glasshouse, avoiding the frustrations of growing outdoors. No more plants being drowned by torrential rain, frozen and battered by the wind.

In a Polytunnel or glasshouse you will enjoy an extended growing season, being able to plant earlier in the season with less risk of frost (and even earlier again if you use a frost protection heater) and enjoy plant growth longer than is possible outdoors.

If you are new to growing you will be able to enjoy producing healthy organic crops and if new to growing your own vegetables you are in for a surprise as the taste of fresh vegetables picked and eaten the same day is really fantastic.

Lastly, if you have found Murphy’s law to be true that whenever you have a day off to escape to the quiet of the garden and the weather is most likely to be awful, with a Polydome Greenhouse your personal space will be available to you year round to forget about work and enjoy your hobby no matter what way the weather is.