It has been about 80 years since the western U.S. has had such hot years back to back.
2014 has accumulated slightly more heat than 2013, as of early August. In Douglas County, the daily average temperatures have been about 4 to 5 degrees above our 10-year average. Most of the temperature gain has been from warmer night time temperatures.
The month of July has been especially warm with total heat accumulation up about 20 percent over our 30-year average. And the forecast for the next three months is for above normal temperatures.
One thing that I have learned as a horticulturalist while evaluating and working with crops is that plant damage in a cool year drought is far less than in a hot year drought. In a cool year drought, plants may get leaf scorch and some cosmetic damage. But when you add excessive heat to the formula, it’s a killing combination. You can’t stop the heat but you can prepare your garden for it.
When you realize we are heading into or that we’re in a hot, dry summer, it’s important to focus on a few good gardening practices like mulching all areas of the garden before the worst heat arrives. Mulch is especially important for those areas where you choose to reduce watering. Multiple research projects have shown that a 2- to 3-inch layer of organic material will keep the soil temperature 15 to 30 degrees cooler than bare soil and slow down evaporation rates from the soil by over 50 percent.
Over time annual organic mulches will also add moisture holding capacity to your soil. I often see people blowing all the organic matter off the soil surface in landscapes to give them a neat tidy look. That is exactly opposite what you should be doing. If you want the landscape to look neat you can grind up bark, leaves, tree trimmings, compost or grass clippings into a pretty fine product.
Research with biochar as a soil amendment shows real benefits for your soil and plants by retaining more moisture and nutrients in the char. This and annually adding humus forming soil additives like compost and cover crops to your garden’s soil will help to make the site more resilient to hot dry summers.
When planning a vegetable garden in a dry or drought year, plan a smaller garden to keep your water bill reasonable. Use soaker hoses or drip irrigation to deliver water efficiently. Pick the plants that you value most like homegrown tomatoes. And choose high value crops that can be grown in a small space or vertically on a trellis like peppers, green beans, herbs and greens.
Let our local farmers grow crops that take more water, space and soil resources such as potatoes, corn, winter squash, melons and pumpkins.
If you would like to learn more about gardening effectively in drought years, think about joining the Master Gardener class of 2015. Come to the Extension office September through November to sign up for our program starting in January.
Steve Renquist is the horticulture extension agent for OSU Extension Service of Douglas County. He can be reached by email at firstname.lastname@example.org or by phone at 541-672-4461.