The Treasure Valley is bursting at the seams with a huge influx of new residents, many looking for more reliable water for growing crops. I hope they’re not holding their collective breath. We do have what nature gives us, an average of 12 inches of precipitation each year. Now that’s just above desert precipitation, closer to steppe values. That is not guaranteed for the future.
I grew up on the eastern slope of the Rocky Mountains learning the value of water and conserving it, where farmers either were linked to irrigation canals – some filled with water from the shrinking Oglalla aquifer – or they resorted to dryland farming, planting in late fall so snow would water frost-tolerant crops. The recent drought in California taught growers some lessons, and it’s good for all of us to be aware of drought possibility, and how drought can be used to our advantage. We’ve had low-water years over the past four or five decades, but no waterless years. Climate change could push drought our way, so we should be prepared.
I recall past years in which water was so insufficient that odd-numbered houses could water on odd days, even addresses on even days. Prolonged droughts have long afflicted the American West, and they may return, so I think we should all conserve water and grow as if water were scarce. Soaker hoses, drip irrigation and Xeriscaping help reduce water use. In Boise, city water is very expensive, even more costly in summer, so it will pay all of us to conserve it.
One way California tomato growers found advantage in drought was in watering less and harvesting more intensely flavored tomatoes. Now restaurants are searching for tomatoes grown like this for their customers. This use of reduced water can be very tricky, since withholding water often results in blossom end rot (calcium deficiency) on tomatoes and peppers. The plants cannot use the soil’s calcium unless the soil is moist. Generally I’ve found a good, long soak once a week is sufficient to prevent blossom end rot on lightly mulched tomatoes even in hot weather, although prolonged temperatures topping 100 degrees usually entice me to use soaker hoses twice a week. This year could be different, since my tomatoes are starting out with thick mulch that will securely hold moisture. Plum tomatoes, though, are so touchy that they might develop blossom end rot anyway.
Use as little water as possible, using drip or soaker hoses, and mulch with organic materials to hold that moisture in your soil. Any organic material and/or humus added to the soil helps retain that moisture, but mulch is a visible conservator. Mulch also prevents weeds (provided weeds were hoed or scraped out before mulch applied), so that soil’s moisture only goes to nurture vegetables, not weeds. This summer for mulch I’m using the leaves my neighbor mowed, shredded and bagged last fall. They’ll decay, and residue will be pulled into the soil in soil pores, by macro or micro inhabitants of the soil. Organic matter added this way benefits soil longer than if it’s incorporated by rototiller, and it provides nutrients for future crops.
Rows of vegetables in a garden bed are a throwback to the days of horse or oxen plowing a field or garden back and forth, so a more modern and efficient way of planting is in beds. You’ll find your harvest will be larger if you plant in beds or squares up to 3 feet wide rather than in rows, but that will have little effect on water consumption, except that overlapping leaves shading the soil prevents evaporation. A block of plants about that size might produce five times the harvest you expected from a row.
Water early in the morning so that, in case water droplets land on leaves, they’ll dry out before hottest sunshine that could turn water drops into magnifying glasses, burning holes in leaves; and before evening, when plants are vulnerable to mold or mildew. Lawns are water hogs, needing an inch of water per week. If possible, use manual control of your lawn-watering system instead of a timer so that you don’t run sprinklers during a rainstorm, and you can easily turn off your system if there’s a fire in your vicinity. Firemen need the best flow of water they can get to save homes and people.
Some folks replace their lawns with pavers, but that just adds to the heat of your house. You should have greenery for 15 feet around your house for each story of your house. And that greenery can be lawn or shrubs or groundcover or even green growing plants in containers. The greenery will help lower your cost of air conditioning. If you are new to this valley, we do need air conditioning. We have had temperatures hotter than 100 degrees for weeks or days in a row each summer for the past few years. Low humidity and cool to chilly nights make the climate more tolerable, however.
Send garden questions to email@example.com or Gardening,The Statesman, P.O. Box 40, Boise, ID 83707.