In the Garden:
Agastache 'Blue Fortune' is a magnet for pollinators, including this black swallowtail.
Plants for Dry Times
When it rains, it pours, but when it stops ... we waste a lot of time watering our gardens. I call it a waste of time because I'd rather be doing just about anything other than standing with a hose or lugging a watering can. Even with automatic watering systems, there's still the issue of whether we should be providing a lot of supplemental water, with droughts becoming more prevalent around the country. I read recently that the month of August was the second driest in the Boston area in the past 100 years.
We all have tropical annuals in our gardens that are extravagant water guzzlers (impatiens come to mind), but do we need them? If we can't live without them, do we need to blanket the ground with them or would a few choice plants in a prime spot create enough of an impact?
When I lived in Colorado I fell in love with the grey-green foliage and masses of tiny flowers common to many dry-climate plants, and even though I now garden in the traditionally moist Northeast, I'm still drawn to them. I mix gravel into my clay soil so I can grow lavender and agastache, and try to keep the mulch away from the crowns so they don't rot in winter. But if dry times lie ahead, these plants may be the stalwarts of the garden.
Xeriscaping is the official term for water-wise gardening (coined in Colorado in the early 1980s), and using this water-conscious lens involves taking a second look at native plants that have proven their adaptability to periods of drought, as well as plants that are native to other regions of the country where rainfall is less abundant. There's lots of information from Denver Water, Colorado State University, and other Western organizations about planning and planting with xeriscaping principles in mind. But for New Englanders it's not as simple as taking plants that thrive in the arid West and plopping them into our gardens. Not all of them will be able to tolerate the moist conditions that alternate with the dry times here in the East. There are many plants generally adaptable to both situations, and you likely grow many of them already.
Trees and Shrubs
Junipers are well known for their drought tolerance, but there are many more interesting low-water-use plants available, including beauty bush (Kolkwitzia amabilis), blue mist shrub (Caryopteris spp.), chokecherry (Prunus virginiana), cotoneaster, flowering quince, lilac, ninebark (Physocarpus spp.), potentilla, rugosa rose, Siberian pea shrub, and staghorn sumac.
I love all the agastaches, with their licorice-scented foliage and tall, hummingbird-magnet flower spikes, but I've killed a few by planting them in a low spot where it stayed too moist. Some varieties -- 'Blue Fortune' and 'Desert Sunrise', in particular -- are tolerant of occasionally moist soils.
Other adaptable flower choices are bergenia; brunnera; columbine; coreopsis; dianthus; echinacea; echinops; gaillardia; gaura; gazania; bearded, German, and flag iris; penstemon; rudbeckia; Russian sage; salvia; veronica; and yarrow.
Many drought-tolerant perennials have grey-green foliage that complements many colors of flowers and even holds its own without flowers. A friend planted short dianthus (don't know the species) as a ground cover, and it's eye-popping. Other drought-tolerant choices: artemisia, catmint (Nepeta spp.), coralbells (Heuchera spp.) hens-and-chicks (Sempervivum spp.), lamb's ears (Stachys spp.), lavender, snow-in-summer (Cerastium tomentosum), and thyme, especially woolly thyme.
Ornamental grasses blend beautifully with many of the billowy and bushy drought-tolerant perennials. Choice options are 'Karl Foerster' feather reed grass (Calamagrostis acutiflora 'Karl Foerster'), blue fescue (Festuca glauca), blue oat grass (Helictotrichon sempervirens), and maiden hair grass (Miscanthus sinensis).
If you've grown cosmos you know they rarely need water. The same goes for globe amaranth (Gomphrena globosa), lavatera, nasturtium, portulaca, and Zinnia angustifolia.
Group the Guzzlers
As for favorites that are less water thrifty, such as astilbe, filipendula, cardinal flower, and tropical annuals, plant them in a low spot or against a north- or east-facing wall or on a north- or east-facing slope. At the very least, group them together in the same area of the garden. Then if you do have to water them, you won't waste time and water on those that don't need it.
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