Some of you may already be thinking, well, that’s obvious: through transpiration, plants give off oxygen, and they take in our carbon dioxide waste.
That’s true, and very important, but that wasn’t what I meant. What I’m talking about is the circulation of air in the garden.
For someone like me, who wants to cram as many kinds of plants as possible in a small place – somehow being artistic about it – the idea of air circulation came gradually. But if you see certain plants dying or just being morose all the time, you start to wonder.
Finally I read (probably in Graham Stuart Thomas, purveyor of articulate, observant, and good-humored rose information) – finally I read that roses need air circulation. They need air flowing all around them to thrive. So if you cram them in with plants of a similar height, after a while, they start looking cheesey.
They need more air.
When I thought about it, I realized that our wild roses grow with maximum air circulation. They form huge mounds, but those mounds of roses are dotted throughout a meadow – air circulation in between the bushes, and air circulation through the meadow (you only find California wild roses in clear areas, or areas that have once been cleared).
When I found out that my lilies weren’t doing well because I had too many tall plants mashed in with them, I changed my planting habits – and got more flowers and healthier plants. Lilies like their roots cool, so covering their ground with low plants is a good tactic. And this, too, is how I’ve seen lilies grow in the wild: most often in low ground cover or thick duff (the wilderness equivalent of mulch).
Mediterranean plants, such as herbs, like a lot of circulation, too. That makes sense when you consider they are basically chapparal plants, dotted over a stony landscape, often on slopes, where air circulation is even better.
Knowing how plants grow in the wild gives us useful clues about how they’ll do in our gardens – and incidentally, helps us know our plants better. If you have plants which are mysteriously languishing, you might consider giving them a little air.