Wow, it’s dry this year! This is a common refrain among visitors to the Botanical Garden. Straw-coloured lawns greet us when we arrive at the Garden, and one doesn’t have to look very far outside of the Garden to see crispy perennials and shrubs, and stressed trees. People are quick to point to Metro Vancouver’s water restrictions, and certainly, the rules make it difficult to keep plants thriving in hot weather, but this is not the whole story. There’s no denying that prolonged drought can be hard on garden plants and that as a society we don’t make the connection between water conservation and weather—that is, until we’re faced with serious water restrictions. And again, we have to admit that many established landscapes in Vancouver are absolutely dependent on summer irrigation. Vancouver’s soils, especially around UBC, are shallow and well-drained, and a good number of our garden plants (many rhododendrons, for example) hail from parts of the world that experience considerable summer rainfall. In some years in Vancouver, summer rainfall is only an unexpected treat. The next time someone you know curses our winter “monsoon” be sure to remind them those rains fill our mountain lakes, which is the only thing that allows us to water our gardens in the summer.
Trees, perhaps more than any other kind of plant, define our landscapes. Can you imagine the city or the Botanical Garden without trees? They are our most important planted assets. When we grow trees, we are doing so for the future. The leafy canopy that cleans the air, gives cooling shade and a home for birds, is provided by a tree that was planted by someone years ago. Even in the depths of drought, most of our established trees can find enough moisture to hang on, but small trees and especially, young ones are a different matter. In times of water shortage, these trees often need our help. Luckily, good summer maintenance of younger and smaller trees usually means merely deep, infrequent watering. This ensures that roots grow down, where they’re better insulated from drought (and freezing in winter) and where there’s a higher probability of finding moisture. The car will survive a few months of not being washed. The sidewalk can be swept with a broom. The lawn is going to recover with the onset of rain in the autumn. Without watering, some of our trees may not survive. Hopefully, if we all do our part and the weather cooperates we can avoid moving to Stage 4 water restrictions.
There is plenty of plant interest in the garden despite the dry conditions. You can see photos in our forum here.
Article submitted by Douglas Justice, Associate Director, Horticulture and Collections, July 31, 2015.