As a group, gardeners are generally aware of the cycles of nature, the seasons, and the weather. Gardeners are also the ones who are the first to notice when we seem to be going into a drought. But even non-gardeners must be aware that the climate has become unpredictable. As the frequency and amount of rain has become one of the most erratic elements of nature, we often wonder what we can do to reduce our angst as we watch our prize-winning petunias shrivel up and die from lack of water.
On the East Coast, we take water so much for granted. I spent some time in Colorado this year and saw up close how fortunate we are. Denver has on average only 17 inches of rain a year as opposed to our average of 41. Denver Botanic Gardens is leading the way in educating the public about more appropriate drought tolerant plantings that will be able to survive both the harsh, long winters and the erratic arrival of moisture in Colorado. What can we learn from Denver and other places across the country?
In my own garden, I have been experimenting with low water use perennials. I was inspired to do this not just because of the threat of imminent global climate change, but also in order to grow many of the silver-leaved herbs that I love, which were not growing well in my traditional herb garden.
While visiting Provence, France one summer, I noticed that the rosemary, thyme, and lavender were growing in the grit by the side of the road. I realized that I was being too nice to my herbs; they needed leaner soil and less water to thrive. So was born my gravel garden—ordinary top soil mounded into little hillocks and then mulched with two to four inches of river stone. Now in its third growing season, the garden’s plants are watered in and then they are on their own. Although, I have watched some plants die, in general, the gravel garden has been a huge success.
So, what are these amazing plants that survive without additional moisture? Many of them are common. Silver-leaved herbs thrive, as do other silver leaved Mediterranean plants, and Agastache, variegated Yucca, Knautia, Blue Fescue, Helianthemum, and Pasque flower are now jostling for elbow room, where once they were isolated islands in a sea of gravel. The sedums have also done well, but no surprise there; these are the plants that put the “green” into our “green roof” on top of the Intercollegiate Athletics Field House on campus.
I am very pleased with the results of my experiment and would strongly suggest that you try a similar one in your own garden. Also, try to reduce water use. Choose plants that require less regular watering and think about your whole lawn care regime — reduce or cut out chemicals, fertilize wisely, and water less often. Watering deeply encourages the development of the deep, water-seeking roots, which may allow the plants to survive drought conditions. Also, try gravel as mulch instead of organic material. For container gardens, move up a pot size and use ‘soil moist’ or other water-holding gel with your potting mix. This will allow you to water less often.
We should plan ahead to make sure that our gardens are prepared for unpredictable drought conditions. If you plant sensibly, you will not only save water, you will also have more time to enjoy your gardens.
— Jenny Rose Carey, Director, Ambler Arboretum of Temple University