How to Repair an Old Greenhouse

Greenhouses are an odd possession. When they’re new and in perfect working order there can be few more pleasant things to own. They’re the perfect opportunity to get seeds started early, to grow crops you otherwise couldn’t, and to extend the growing season late into the year.

The problem comes when greenhouses start to get a little old and frail. Grass panels can break. Aluminium frameworks get tired and bent. Before long that dream greenhouse turns into an eyesore – and a growing annoyance.

After all, how do you remove a greenhouse that you no longer want? All that glass is just waiting to get broken, while the frame is big and bulky and almost certainly won’t fit in your car. For this reason, many people end up giving away unwanted greenhouses to anyone daft enough to come and collect it.

This was certainly my own experience of greenhouse ownership. When I took on my allotment the previous tenant had taken almost everything they could with them – tools, barrows, railway sleepers and even fruit trees. What they couldn’t be bothered to take, however, was a tired old greenhouse that had been slowly left to fall apart. What a waste.

But also what an opportunity!

In this article I want to talk you very quickly through how I managed to transform a tired, bent old greenhouse frame with only a couple of panels of glass left, into a fully-working greenhouse.

Oh, and I did it on a budget…

Glass Removal

You don’t want to cutting yourself in the garden if you avoid it; the host of bacteria to be found there can make for an unpleasant experience. With so few panes of glass remaining in my “adopted” greenhouse, and most of these being cracked or chipped, I took the option of removing them all entirely.

Start off by getting yourself a study container, such as a plastic bin or a Really Useful Box. We can then place the unwanted glass into it, preventing broken glass from getting into your soil.

Carefully remove the metal clips that attach the glass to the frame and, wearing sturdy gardening gloves and goggles, gently remove the panes and place them into your chosen container. Take your time on this part, as you don’t want broken glass everywhere.   

This can then be disposed of it is broken, or gently cleaned if you plan to re-use what you can.

Frame Assessment

Now you’ve eliminated the risk of broken glass the next step is to assess the all-important frame. Ideally, the frame will be in tip-top condition, but aluminium frames in particular can become bent and buckled over time by weather or physical damage.

Personally I was able to use a hammer to gently straighten any bent elements, but if necessary remove damaged sections and replace them. Many better garden centers sell spare greenhouse frame pieces, or even easier they can be bought online and delivered to your home within days.

General Cleaning

Greenhouses attract a lot of dirt over the years. From cobwebs, to bird mess, to dead, dried-up old plants, an unloved greenhouse can quickly revert to a very wild state.

Use a stiff brush to remove dust and dirt, chop away any unwanted plant material, then scrub the frame with hot soapy water and a brush. You’ll be amazed at just how much a difference this can make; not only aesthetically but also to ensure all the parts of your greenhouse run smoothly.

For example, in my case the greenhouse door was unmoveable. I removed it and cleaning the runners thoroughly, also oiling the wheels that make contact with the runners. After reattachment the door moved like new.   

Cheap Greenhouse Glazing

Possibly the most challenging part of the whole process was how to reglaze the greenhouse. After all, the frame alone has no real value to me; I need my greenhouse to keep out the rain and keep in the warmth.

After some discussions with local glaziers I made two decisions. Firstly, ordering panes of glass for your greenhouse is an expensive proposition. Secondly, of course, glass has a nasty habit of getting broken. And I don’t want broken glass all over my vegetable plot. If I’m honest, there had also been some thefts of greenhouse glass on local allotments too, and the last thing I wanted to do was to spend a load of money only to have all the glass stolen a few weeks later.

What I needed was a different solution; something cheap, practical and sturdy. And I found it in twin-walled perspex.

I chose twin-walled plastic for a couple of reasons. Firstly, it’s much, much cheaper than glass. Secondly, the “double glazed” design means that it is fantastic at trapping hot air inside. Thirdly, and just as importantly, it can be cut to size with a craft knife – no skills needed.

The process was therefore pretty simple. I measured up the panels that I needed, then found a plastic-supplier online. For a 10% surcharge they cut all my plastic to roughly the right dimensions, and a week or so later all my panels arrived. The total cost? Less than £70 (~$100) for the whole lot.

All I needed to do was to make a few minor adjustments with my craft knife, then use greenhouse glass clips to attach the panels to the frame. I also added some strong gaffer tape to parts of the frame that seemed a little misshapen – to ensure my panels didn’t blow away in the wind.

And that is it! From arriving with the package, to having everything set up, took just an hour or two. Even better, this plastic has been doing its job for over 5 years now without a problem. All I do is remove it at the end of the season (as we get some strong winds here during the winter) and store it in my shed. In April each year out come the panels and everything is set up again in record time.

The way things are going, that initial investment in plastic will work out to be less than £10 per year for my fully-functional greenhouse. Quite a bargain I think you’d agree!

Back in Business!

In closing, I wanted to show you a few photos. Below you’ll see the state of the greenhouse frame when I inherited it, and what it looked like after a little work.

And to prove just how effective this plastic glazing is, here are a few examples of crops that I have successfully grown in my greenhouse. Each year I pride myself on my crops of cucumbers, peppers, tomatoes and melons that I’m able to produce – all from this tiny greenhouse in chilly old England and a one-off investment in lightweight plastic panels.