A Drought-Tolerant Garden

Moving to an area of the country that receives, on average, around 52 inches of precipitation a year gave me little incentive to think about drought when I began to plant. In fact, just last year the month of May brought severe flooding that damaged much of downtown Nashville.  But summer has been a very different story the past few years. Even though the air is usually humid during the months of July, August and September, those months brought many weeks without any measurable rainfall. After surveying the yard and gardens at the end of the growing season, it occurred to me that most things had come through the heat and drought well. That got me to thinking about what had been planted and the great variety of plants that are actually considered to be drought-tolerant.

First, let me say this is not about cacti and succulents or xeriscaping or rock gardens. Those are all great topics to explore, especially if you live in or near an arid area of the country or in any area where there are restrictions on the use of water. When you say the words drought and tolerant together in the same sentence, people often do think of the plants and topics just mentioned.  Although I am very fond of succulents and cacti, many people are not.  For some, they bring to mind a hot, barren environment full of thorny things that seldom bloom and that are always situated in a sea of gravel and white rocks.  This is definitely not about that.

While not purposely setting out to plant drought-tolerant gardens, it appears that is what has happened.  And I am very pleased with the results, especially since the yard now contains lots of bloom color over a long period, lots of lushness, and lots of interesting growth.  All this has been achieved by planting things that are termed hardy.  Love that word.  I now look for anything for sale here that bears it.  The USDA plant hardiness zone map and its designation of hardy are used to indicate that a plant is at least root-hardy to a certain temperature and will most likely survive over the winter in a particular location.  It seems many of those cold-hardy plants are also heat and drought tolerant as well.  Recently, some agencies and organizations have begun to develop plant heat zone maps as well as to provide information about a plant's expected heat and drought tolerance. 

Sometimes gardeners, including me, zone-push just for the fun of it.  We plant things that are are not categorized as hardy in our zones.  With just a little mulching, many things can be grown here that I initially had thought wouldn't make it through the winter.  On the other side of the coin, there are also a lot of plants that will provide color and interest over a long growing season which includes high temperatures and drought and still remain looking good while doing so.  Pictured below are some of them.

Since I am interested in perennial gardens, most of the plants pictured are perennials; a few are annuals from which it is easy to collect seeds for replanting the following year.  These have all proven to be no muss, no fuss plants . . . and all are hardy and drought-tolerant here as well as in many other locations around the country.  Additionally, the plants shown below are growing where they receive full hot summer sun for 6 or more hours a day.  New plants will require more watering the first year until they are well-established.  Fortunately, once established, many plants will do just fine without frequent watering.  Hover over the pictures for names and additional information.

Planting for dought tolerance and climate change can be challenging but also very important.  It's no fun at all to put a lot of time, energy and money into planting things that don't survive.  While every yard contains its own micro-climates and no plant is guaranteed to always thrive in any location or zone, it pays to double-check plant hardiness zones or maps before choosing what to plant.  To illustrate that point, my current zone changed from zone 6 to zone 7 over a period of 15-20 years.  Zones have tended to become warmer and sometimes drier or wetter.  Not all hardiness zone maps reflect those changes.  It's a good idea to check several different maps or guides before planting.  Additional information about climate zone changes can be found here.      

Other drought-tolerant perennials include African Daisy, Asclepias tuberosa, Baby's Breath, Baptisia, 'Becky' Shasta Daisy, Black-eyed Susan, Blue Fescue, Broom Sedge, Bronze Fennel, California Poppy (not cold-hardy but a heavy reseeder), Celosia (not cold-hardy but reseeds easily), Coreopsis, Nepeta, Morning Glory, Eryngium, Fountain Grass, Gaura, Golden Aster, some Iris, Hardy Lantana (moderate cold-hardiness), English Lavender, Liatris, Heuchera (sun and shade varieties), Horseradish, Rosemary, the Mints, Penstemon, Santolina, Leonoitis (moderate cold-hardiness), Kniphofia, Ruellia, Oregano, many Salvias, Miscanthus, Armeria, Natives and Wildflowers, Valerian, Vinca, Wild Ageratum, Yarrow.  Remember to check cold-hardiness before planting any of these in your zone.

Lastly, a word about roses since so many people love them and enjoy growing them in their yards and gardens.  In most literature about drought-tolerant gardening, there seldom seems to be any mention of drought-tolerant roses.  However, a number of roses have their ancestry in dry areas and many of the original garden roses were brought from the Middle East, a notoriously dry region.  In my own experience, the 'Knock Out' variety of roses, the rugosas, and Rosa banksiae have flourished with little care and infrequent watering.  In fact, it is thought that the largest rose in existence is a white Lady Banks Rose (Rosa banksiae) located in Tombstone, AZ, which receives an average yearly rainfall of just 14 inches.  The rose was planted in 1885 and now covers over 8000 sq. ft. with a trunk circumference of over 12 ft.  Lady Banks Rose is a thornless climber and is also available in a yellow variety (Rosa banksiae 'Lutea'). 

Rosa rugosa seems to do fine in poor soils, high heat and drying winds while producing an abundance of spicy-scented flowers followed by bright red hips, attractive to birds, in the Fall.  While 'Knock Out' roses are not scented, they are very easy-care roses that provide an abundance of single or double blooms over a long period. 

Another non-thirsty rose is 'Iceberg' which can be grown as either a floribunda or a short climber.  This somewhat shade-tolerant rose is available in white, pink and burgundy colors and is considered by many to be one of the best floribunda roses of all time.  It is mildly fragant and hardy to at least zone 5.