Gardeners know Colorado’s weather wreaks havoc on plants, and it’s not getting any better with global warming. But the way you garden can make a difference in slowing carbon emissions.
Here are sustainable gardening tips from a community gardener.
Text and plant photos by David Wann
Gardening in the Front Range is never a cakewalk.
And it’s not likely to get any better. 2010 was the planet’s warmest year on record, and each zone in Colorado—plains, foothills and mountains—has moved up a notch on revised USDA hardiness maps. (Find your zone by typing in your zip code at arborday.org/treeinfo/zonelookup.cfm. You can also find tree and shrub suggestions.)“Ours is the wildest weather on the planet,” says Boulder landscaper Jim Knopf. “Arctic fronts collide with tropical air masses here, creating an ever-changing house of horrors.”
The Front Range is heating up, and we should prepare for even more bizarre temperature swings, with longer drought cycles, gustier winds and more frequent hail (Ouch!). We growers need to sharpen not only our tools, but also our skills and knowledge. The good news is that many adaptive gardening techniques can actually help prevent the worst effects of climate change.
Planting winter rye, vetch, field peas, Dutch clover and other off-season cover crops helps absorb carbon dioxide and puts it into the soil when these crops are turned under in spring. This feeds soil microorganisms that happily inhabit the root zone, aerate the soil and help plants take up nutrients.A critical goal is to absorb greenhouse gases, like carbon dioxide, out of the air and into plants and soil on a continuing basis. This is a perfect match with what successful Front Range growers do anyway—enrich our carbon-poor soils with organic matter like compost, leaves and manure, which help retain water and store carbon at the same time.
Soil building also reduces the need for synthetic fertilizers, which are very energy-intensive to manufacture. Pesticides and potable water use a lot of energy too, but with good gardening and landscaping practices, we can reduce both energy consumed and gases emitted—and help the planet chill out.
Four techniques that can help a garden adapt to increasingly warmer temperatures are mulching, to hold in moisture and keep the roots cool; planting varieties that can withstand harsh conditions; installing a drip irrigation system to deliver water directly to the root zone; and using simple structures that can stretch the growing season in cooler months, shade crops in hotter months, and protect plants from morale-busting hail. (What a great relief it is to see your garden survive a hailstorm!)
My favorite mulch, especially for acid-loving crops like potatoes, is pine needles. I collect needles from schoolyards and parks in late fall. (The trick is to catch the grounds crew in the act of raking.) During our windy winters, other mulches like leaves, straw and wood chips blow into the next county, but pine needles stay put.When a dry spell drags on and on, stockpiles of mulch keep vegetables and landscapes happy. Once-living materials like compost, leaves, spoiled hay, grass clippings and pine needles keep moisture in the root zone, control weeds that would otherwise steal water from the crop, and moderate soil temperatures.
In the vegetable garden, peppers, tomatoes, beans, beets and basil can withstand heat pretty well if their roots are kept cool and damp. But most salad and cole crops—broccoli, cabbage, kale and cauliflower—appreciate mulching, shading and afternoon cool-downs with a watering can or hose.With high-carbon mulches like sawdust and wood chips it’s best to layer compost beneath the mulch, so the process of decomposition doesn’t steal nitrogen from the crop.
Especially prolific and heat-hardy vegetables include Winter Density, Tango and Red Sails lettuce; Detroit red beets; Premium Crop broccoli; Whirlybird nasturtium; large-leaf basil; Zephyr summer squash; Toscano kale; Carmen bell peppers; Sungold cherry tomatoes; Waltham butternut and Ebony acorn winter squash; Nelson carrots; and Yukon Gold potatoes.
Drip irrigation not only conserves water, it keeps soil cool and moist. A drip system can be as simple as a soaker hose that you control manually or as comprehensive as a “T-tape” system with preset drip holes on a timer (which is fairly easy and affordable to install). It’s important to not overwater, however.
Be a Drip!
A reliable moisture meter is a good tool to have, as well as a constantly expanding understanding of how much water crops actually need. Tomatoes, for example, are not as thirsty as we think they should be, while beans are especially thirsty, particularly when the pods are developing. Bean leaves turn light green to grayish when they’re really dry, and squash leaves wilt dramatically on hot afternoons, even if they have plenty of water.
Most vegetable crops need extra water when they’re establishing roots, flowering and developing their final products. Otherwise, deep watering one day and drying-down the next is a good rule of thumb.
In cooler months, cold frames and hoop-houses that can be covered with plastic are useful garden structures. Shade cloth is great when temperatures soar. All help to finesse changing weather conditions. A chicken-wire hoop frame and a closable tempered-glass cold frame provide emergency hail protection, too.
Homemade circular hoops made with mammal-proof fencing like PVC piping are great for growing tomatoes, cucumbers, peppers and other broad-leafed crops. The hoops also enable a frantic grower to throw old sheets and blankets over plants at the first sign of hail. On days when hail is a possibility, better to be safe than sorry—throw shade cloth or sheets over the hoops when you leave home.
The way we landscape our yards also plays a major role in how much energy our houses use. By planting the right trees, shrubs, vines and grasses in the right places, we can keep our houses cool in summer and warm in winter, by design. This can reduce winter heating bills by as much as 25 percent and summer cooling bills by up to 50 percent, which also reduces energy-related greenhouse gas emissions.
The most effective way to keep a home cool is to prevent heat buildup in the first place, so keeping hard surfaces cool is important. Trees and vines create cool microclimates around walls, pavements and other hard surfaces that reduce ambient temperatures dramatically. Planting shrubs, bushes and vines next to your house creates dead air spaces that insulate your home in winter and summer. Leave at least a foot of space between full-grown plants and your home’s wall.
Colorado State University Extension agent Steve Cramer suggests Rocky Mountain juniper and eastern red cedar as sturdy, durable evergreens for yard-warming windbreaks. His favorite low-maintenance shade tree is hackberry. “It’s a medium-speed grower, so it doesn’t get brittle, breakable branches. That’s a great quality for a tree planted near your house,” he says.
Cramer also recommends Virginia creeper as a dependable trellis-climbing vine to enhance energy conservation (it also turns a brilliant fall red). Other good bets for shady areas are wintercreeper (also a trellis climber) and English ivy, a gripper. For sunny locations, Cramer’s favorite is the clematis vine with brilliantly colored flowers.
All these ideas can help your garden adapt to climate change, increase your vegetable plants’ yield and give you peace of mind by knowing you’re gardening in a planet-healthy way.“Use a large bush or row of shrubs to shade your patio or driveway,” he suggests. Plant a hedge to shade a sidewalk and use fences, windbreak plantings, and shade trees to provide a “sun pocket” on the south side of your home. This will create a place to be outside even in cooler months. (For shrub suggestions see “10 Sun-Loving Shrubs.”)
David Wann runs a community garden in Golden, Colo. He has authored 10 books on gardening and sustainability, including his newest release on sustainable living, The New Normal: An Agenda for Responsible Living. Visit davewann.com for more info.