From the archive - hothouses

The early scientists, (alchemists? wizards?) who turned sand into glass did us modern-day hothouse growers an enormous favour. Everyone who’s ever looked through a window; from Good King Wenceslas on the Feast of Stephen, to Her Royal Highness in her golden horse-drawn Coronation coach, should thank those glassmakers of yesteryear, for providing the portals through which we can view the world without having the world come in and snow, hail or blow on us while we do so. But it’s us under-cover growers who should be most grateful, for it’s us who make the most of the opportunities provided by glass. We don’t just take in the view that glass offers us, we use it’s sheltering characteristics to grow food – surely the noblest of all behind-glass activities (I realize this claim is highly debatable; the owners of aquariums filled with tropical fish might want to dispute the ‘most noble’ claim, as might oceanographers looking out at the marvels of the deep through the toughened-glass portals in their bathyscaphes, but this is a column about glasshouses, so I’ll stick to what I’ve said).

Things might have gone the other way, of course. If the fusion of silica hadn’t been stumbled upon/discovered by those proto-glassmakers, we might even today be trying to grow our tomatoes behind shaved and stretched sheep skins or oiled birch-bark. Glass is a magic material. It’s tough stuff, though scientists say it’s not solid, and can withstand surprisingly vigorous attacks by hail, woodpigeon and errant Christmas kite yet allows the gentlest sunlight through – how, I’ve never understood – light’s a particle and a wave I’m told and that’s supposed to explain it. But let it through it does, and we gardeners exploit that feature to the max. What glass can’t easily do; bend, fold, succumb to being cut by a pair of kitchen scissors, we use plastic for. Modern skins of clear plastic are tremendously versatile and allow the engineer/designer (that’s you, homegardener-with-initiative) to build a hot house in any and every form imaginable; any shape, any size, any anywhere. If you can fashion a frame, you can swathe it in plastic. I think we New Zealand under-cover growers have yet to get jiggy with our tunnels. We’ve kept, in the main, to the basic ‘loaf’ form, utilizing commercial frames and not rocking the design boat even when we make our own tunnel houses, but there’s little stopping the bold artist/gardener from sticking/gluing/clamping together a completely original pleasure-dome for the purpose of raising tomatoes and chillies. I’ve seen some good efforts in both plastic and glass house-construction; children’s climbing frames appropriated for the purpose and wrapped in plastic, tight as a drum, bamboo poles of the widest caliber, arranged geodesically or in the shape of a tipi then covered in clear plastic to make a hothouse John Lennon would have been proud to own.

I’ve been invited to inspect add-ons as well; lean-to’s and ad hoc conservatories where an unused east, north or west wall has been converted into a hot-spot for limes, tamarillos and cape gooseberries, by the clever arrangement of second-hand window frames, old French doors, even lengths of black alkathene pipe, hooped and secured then enveloped in clear plastic. I like them all but still yearn to come across the Fantastical Hothouse of Previously Unimagined Design.