Still dry

As of September 1, most of Massachusetts is officially suffering from severe to extreme drought conditions. How are plants and people coping with the drought?

    What I see happening to plants around town is sad and alarming. Leaves of some trees have turned completely brown and dropped off early. 

A pin oak (Quercus palustris) cuts its losses

Sometimes it’s hard to see why one tree or shrub is suffering, while another nearby seems to be relatively unscathed.

    The reactions of two hydrangeas about ten feet apart in my front yard are puzzlingly different. One wilts almost every day, has dropped all leaves from some branches, and looks as if it’s near death, despite my watering efforts. 

This hydrangea can't catch a break

The other is still just as perky as it was this spring, holding its bright green leaves up to the sun as if there were no problem at all.

This one is doing fine

    I went to the Internet to find out what’s going on. North Carolina’s Cooperative Extension provides a useful article on plants’ response to drought. The author, Barbara Fair, PhD, explains that when plants can’t get water from the soil, they go into crisis mode, jettisoning important functions. Wilting, letting leaves hang vertically when not enough water comes from the roots, changes the angle at which the sun’s rays strike the leaves, reducing water loss. 

     In these conditions plants send chemical signals to their leaves to close stomata, pores that let water out. If the stomata stay closed too long, preventing evaporation and water flow through plant tissues, the plant can suffer from both over-heating and nutrient deficiency.

    Next desperate measures include sacrificing some leaves, twigs or branches to save energy and stopping production of chemicals that protect the plant from attack by insects, fungi and bacterial diseases.

This horse chestnut (Aesculus hippocastanum) prioritized making seeds over saving leaves

    My hydrangea’s problems could be multifactorial. It may be an especially thirsty cultivar. It may be in a slightly hotter, sunnier, or better drained spot than its compatriot, though both are in part shade. Roots of a nearby oak could be capturing the minimal water available, leaving the drooping hydrangea dry.  The shrub could even be suffering from a wilt disease, to which drought stress makes it more susceptible. 
  
    The drought response of the people around me varies. A valiant member of the Holden Garden Club, faced with an outdoor watering ban, has been collecting the not-yet-hot water from her shower in a bucket for her plants. Meanwhile, neighbors in my city, under no watering ban, are proceeding with sprinkling newly seeded lawns as if there were no drought. 

Watering during sunny days maximizes loss to evaporation

    I’m no water hero either. I’ve stopped squandering water on my lawn, but I’ve continued irrigating garden beds—less often--and watering container plants by hand. As the drought drags on, I too have resorted to saving water from indoors for some thirsty plants. In my case it’s rinse water from the kitchen sink. 

     While I think reseeding a lawn right now is going too far, I can sympathize with the impulse. It’s hard to watch your garden dry up and die.

Late-breaking news--it rained today! The water barrel is filling up at last.

Dry and thirsty

The recent heat wave following on a months-long drought displays the many mistakes I made regarding water when I designed my garden. In hindsight, it’s easy to see better choices I should have made.

    Most basic was plant choices. Xeriscape, a water-conscious approach to garden design, provides guidelines for selecting plants that don’t need supplemental watering. Some tips: smaller leaves generally need and lose less water, grayish or fuzzy foliage usually means a plant is drought-tolerant, low-growing plants avoid drying winds, and plants with a scent, such as lavender, produce aromatic oils that help plants hold onto water. I did end up with some plants with each of these characteristics, but not out of any conscious plan.

Gray, fuzzy leaves of lambs' ears (Stachys byzantina) conserve water

    Next, I should have grouped plants based on their water needs. Putting thirsty hydrangeas next to water-sipping catmint, with its small gray leaves, might have looked nice, but it meant I under-watered the hydrangeas and probably used more water on catmint than it needed—though it didn’t complain.

 

Hydrangeas need a lot of water

    Then there was my choice of irrigation method.

Sprinklers lose water to evaporation

The sprinkler system we installed was standard for our city, but I could have saved on evaporation by using soaker hoses, which sweat droplets of water, or drip irrigation, with small emitters that deliver water precisely to the spot its needed at the base of a tree or shrub.

    My rain barrel is a small step toward collecting rain to irrigate the garden. 

The rain barrel is great--when it rains

I wish I’d thought to install an underground cistern to store all the rainwater that falls on the roof before I planted my garden. If I had, in an average year the cistern could have supplied my garden’s irrigation needs. This is certainly not an average year, though. To irrigate with rainwater, you have to have rain, and this year that’s been scarce.
 
    So at this point, my garden is looking sad and parched. 

A forsythia wilting outside the range of the irrigation sprinklers

With a guilty conscience, I supplement scheduled irrigation from the sprinkler system with evening use of a rotating sprinkler to revive wilting plants in areas the automatic system misses (evening watering is recommended to minimize evaporation). 

     We get our water from the Quabbin and Wachusett reservoirs in western Massachusetts, and our water authority hasn’t imposed a watering ban so far. Not so lucky are gardeners whose water comes from town supplies, nearby rivers, or wells on their own property. I can only imagine how painful it would be to watch cherished plantings die from lack of water.

    If I ever build a new house, I’ll put in that underground rainwater cistern before I start planting, and I’ll push for a graywater system too. That would collect water from sinks, dishwasher, clothes washer, and shower to reuse for irrigation. The city of Las Vegas has this all worked out long since. 

     In the meantime, I’ll make sure I dump water from the sink on garden beds when I can instead of letting it flow down the drain, and I’ll think about less lawn and more drought-tolerant native plants for next year.

Cucumbers on the deck benefit from any spare water from the sink

 

Where water is scarce

We came home Saturday night from a week away from the Massachusetts winter, visiting Austin, Texas and Las Vegas, Nevada (Sunday morning the thermometer read -5 degrees, a reminder of why we left). Both cities have climates very different from Massachusetts’. It was nice to get away from the snow, and it was also a good lesson in what kind of gardening is feasible in areas with less rainfall.

    Austin’s climate is classified as humid subtropical, with 228 average sunny days per year and 33 inches of annual precipitation, less than the national average and a lot less than my area’s 45 inches. 

Water-sipping live oaks line a street in the SoCo section of Austin

During our four-day February visit, the weather was lovely, sunny and in the sixties. The plants that caught my eye as most striking and emblematic were agaves.

A giant agave, right, next to a prickly pear

 Huge ones grew in many front yards, where admirable residents were planting appropriate, water-efficient natives.

Tanks store rain for watering Zilker Botanical Garden

     
 I visited the Zilker Botanical Garden, where an impressive water harvesting system collects rainfall to irrigate the garden.

 
     Las Vegas, of course, has a hot desert climate with 4 inches of rain per year, and it’s almost always sunny. During our visit we enjoyed daytime temperatures in the sixties and seventies. 

     At the Botanical Garden at the Springs Preserve, I saw what kind of plantings would be climate-appropriate, including a collection of Mojave Desert cacti and succulent plants. 

The nearby Nevada State Museum featured exhibits on how the construction of the Hoover Dam supplied the city’s water needs. Despite strenuous conservation efforts far in advance of what we see in the East, Las Vegas couldn’t exist without water from Lake Mead.

    This visit to the arid zone reminded me to appreciate Massachusetts’ relatively plentiful water supply. We can learn a lot about water harvesting and conservation from places like Austin and Las Vegas that have been forced to get good at it. Nonetheless, we start with a lot more water to work with. When May comes, I’ll be glad of that.

Waste not, want not

California’s drastic drought has me thinking about the way I use water in my ornamental garden in Massachusetts. Someday I may be forced to change my profligate ways. I’m starting to think sooner would be better than later.

            My earliest gardens were small enough to water with a big watering can or a hose and watering wand.  When I cultivated more ground, I switched to rotating sprinklers.

The biggest negative to that approach was the operator—me. I hate to think how many hundreds of gallons I wasted by forgetting the sprinkler was running. 

            Finally my garden got so big that I moved up to an automatic sprinkler irrigation system controlled by a computer in the basement. The computer doesn’t forget to turn the water off.  It’s programmed to start watering at 3 AM, when the air is cool, but some of the water still evaporates. In retrospect, drip irrigation would have been a more water-saving approach for trees, shrubs, and perennial beds.

            The sprinkler irrigation system uses a lot of water. Comparing water bills before and after we installed it brought me up sharp. I’d tripled our household’s summer water use. I started paring down the water allotted to each irrigation zone, especially the lawn areas, letting the grass turn brown in August.

            We in the eastern US have skewed assumptions about water availability. We’re used to thinking of water as cheap and unlimited, almost like air. That's because the twentieth century was one of our wettest on record. In the future we may be forced to manage with a limited water supply. Using drinking water to irrigate an ornamental garden like mine may become prohibitively expensive or just impossible.

            I wish I’d planted with water conservation in mind, grouping thirsty plants together. Since I didn’t, I’m working on paying more attention to which plants really need supplemental watering. A rain gauge attached to the irrigation system is supposed to prevent automatic watering when rainfall is sufficient. I’d been relying on that and a fixed watering schedule to determine how much water each zone gets every week in the growing season. Established trees and shrubs may not need any extra water, whereas my vegetable garden, annual flowers, and newly planted shrubs and perennials do need regular watering. 

            My plan is to poke a finger in the soil periodically, find out whether it’s actually dry, and see whether plants are drooping. This should allow me to devise a less wasteful watering schedule.

            To this, residents of the Southwest probably say, “Duh!” I’ll catch up eventually.

Water barrel dreams

As I’ve shifted toward more sustainable gardening, I’ve become more aware of stormwater runoff. To keep rain from running down the driveway into the street, two years ago I hooked up a rain barrel to the downspout at the corner of the house and got two strips of porous paving dug into the driveway. 

            The barrel feeds a soaker hose that waters a clump of shrubs near the street. When heavy rain fills the barrel, the porous paving lets the overflow soak down into the soil. During rainstorms it’s quite an amazing and satisfying sight to see sheets of water disappear into the ground as they hit the porous paving, instead of puddling in the gutter. It’s good to be doing my part to prevent stormwater from running into the storm drains, but I’ve started to wish I could capture that water for use in the garden.

            Ken Dews, an expert in rainwater harvesting systems, told me that he got started in the field when he set up a rain barrel at his house and saw it fill up and overflow after one heavy rain. His reaction to the overflow was, “That’s my water!”

            I feel the same. The rain barrel has me thinking differently about rain. Suddenly it seems silly to be using tap water for irrigation. If  I can water one small bed with rainwater, why not the whole garden? I could be solving two problems at once—irrigation and runoff—if I captured the rain falling on our roof, stored it, and used it in the garden. Massachusetts hasn’t yet made it easy to get permits to set up a greywater system, using water from the shower, dishwasher and clothes washer for irrigation. But I could arrange to drain water from house gutters into an underground cistern in the backyard and run the garden sprinkler system off that water supply.  

            Today it rained heavily. As I watched water pour out of the overflow of the rain barrel, I thought it was high time to make the investment in that rainwater harvesting system.