Among my favourite childhood memories is one where upon walking into our family’s rudimentary greenhouse, I was hit by a wave of warm moist air and the rich, vibrant herbal smell of freshly turned earth and wet tomato plants . Looking up at sky through the rain spattered vitrine and crackled putty that just held the glass together I felt both part of, yet safe from, nature.
Today greenhouses have come a long way from their predecessors. Not only are they ingenious practical buildings that enable optimal conditions for growing plants, but they have actually become a backyard design feature. Naturally, the renewed focus on growing your own produce has also boosted interest in the backyard greenhouse.
The notion of the greenhouse functioning as an extended living space has become a reality for many. Greenhouses can even be part of a house if attached in a ‘lean-to’ fashion, as described by Christopher Alexander in A Pattern Language:
‘Imagine a simple greenhouse, attached to a living room, turned to the winter sun, and filled with shelves for flowers and vegetables. It has an entrance from the house—so you can go into it and use it in the winter without going outdoors. And it has an entrance from the garden—so you can use it as a workshop while you are out in the garden and not have to walk through the house.’
Greenhouses, however, are usually stand-alone structures in the garden and are by and large more about function than form.
Whether you choose a Do-It-Yourself greenhouse or custom build one to your specifications, here is a rundown of what you need to consider.
Greenhouses contain features that allow the atmosphere within to be adjusted for light, temperature and humidity. If you live in a cold climate (frost prone); you may need to consider a purpose-built heating option. Conversely, if you are already in a hot, humid climate; you may need additional ventilation, cooling or shade features (like a shade cloth if the sun is really intense). A nearby water supply is essential as is the consideration of the position of the greenhouse to ensure maximum exposure to sunlight.
Structure and Materials
Depending on the design you choose, a typical greenhouse should have a well-drained foundation with a gravel floor that is typically kept wet for humidity. The frame of any given greenhouse should be sturdy. Many DIY kits will use treated steel or aluminium frames but the key to longevity is actually in the quality of construction; its ability to withstand strong wind and constant wet conditions.
While glass remains the material of choice when it comes to aesthetics mainly due to its sheer transparency, there are actually a couple of options in cladding materials. Polycarbonate is a thermoplastic polymer that has the dual benefits of strength and lightness, whilst also blocking 99% of UV rays (which assists in avoiding ‘plant burn’).. Although twin-wall polycarbonate will block 20% of the light and give a translucent appearance to the greenhouse, it provides a double-glazing effect so can maintain steady temperatures better than glass. Alternatively, you can go for the reclaimed organic look by building a greenhouse entirely (or mostly) from old glass doors and windows. You can even make a greenhouse from a simple wooden frame, some cattle fencing and some polyurethane sheeting – although don’t expect it to last more than one winter.
Some research into what plants you want in the greenhouse will be useful before you build your greenhouse as this will dictate the way you arrange it. Be aware that costs tally up rapidly once shelving, potting benches, garden beds, vents (usually in the roof), guttering, shading systems, misting or watering systems, seed tray frames and possible heating systems are considered. Measures to conserve power usage and recycle water within the greenhouse system ought to be implemented wherever possible.
There are many possibilities abound when it comes to greenhouse ownership. For those with the space, a larger greenhouse can accommodate far more than just plants and can serve as a unique extended entertainment area. For many, the ability to harvest vegetables and herbs well into winter may be the main drawcard. Either way, you can be sure that you will reap many rewards from a well-kept greenhouse!