I don’t have a greenhouse, but Peter Henderson had several. So I’m going to him for information on how to save water in a greenhouse.
Those of you who look askance at this old information: think about how much energy modern greenhouse systems often take. Should we turn up our noses at simple solutions if they work, and cost us less in water, time, energy, and money?
Henderson, one of the up-and-coming plantsmen of the 19th century, had an avid interest in solutions that saved all of those things. Managing a thriving nursery business in New Jersey, he felt he was growing in a climate most garden books don’t address, one that was hot and arid. Really, he was comparing his climate to Britain, where English-language gardening books came from. In 1874, U.S.-oriented garden books were still a novelty, though they’d been around since the 1840s (Henderson himself was one of the first in the field). Britain was the standard of reference for the English-speaking gardener.
OK, so compared to Britain, New Jersey is certainly hot, but arid? Anyone who’s sweated softly through the hot steam that is summer air in New Jersey, and seen the basement dehumidier tank fill in half a day, will wonder at that idea. I think he meant that it rains less than it does in Britain. The state of New Jersey’s climate is useful information when considering Henderson’s greenhouse methods, because you know they work in very humid and hot environments.
“A point indispensable in our hot and arid climate is, that all plants in the green-house should stand on close benches, overlaid with sand or ashes, or some such material. This keeps plants moist and prevents the plants from suffering, if any omission occurs in watering. We know that the practice in many places is entirely different from this, the plants being stood on benches of open slat-work. No plant can be kept healthy in such a place, unless with at least double the labor of watering necessary with those standing on sand. This, like many other of our mistakes, is copied from a mode pursued in England, where a colder, moister, and less sunny climate may make it a necessary practice.”
Interestingly, most greenhouses still use the open slatwork benches, or something akin to them. Maybe the U.S. is still in allegiance to England, at least as far as gardening is concerned. Or maybe there are climates where Henderson’s method just doesn’t work. But it sure seems worth a try in places where greenhouse plants suffer from heat and dryness in summer.
For keeping the plants cool, Henderson recommended a then-new ventilation system which opened greenhouse sashes, a single crank-lever serving them all. I’m not sure if Henderson used this method, but old-time greenhouse keepers often painted whitewash on the windows in summer for shade. (Whitewash is a combination of powdered lime and water, and was used as a cheap-and-easy paint on farms for ages.) Whitewash is easily scraped off when cold weather comes again; it’s basically just sprayed-on lime powder, and whatever scrapings are left will actually be good for your plants.
What are your own low-tech greenhouse secrets? When I have a greenhouse, I don’t want it to be a water and energy hog. So I’m collecting information.