Gardening in a warmer, dryer climate comes with challenges
By Bonnie Orr
WSU Chelan/Douglas County Master Gardener
Gardeners have been thinking and mulling over and talking about how much they have noticed the changes in our growing season.
Keeping a gardening journal is one way of noting changes in nighttime and daytime temperatures, precipitation and bloom times. Another source is WSU AgWeatherNet (weather.wsu.edu), which gives climate information in an area near you.
The number of frost-free days in Wenatchee has risen to 196 in 2023. The last day of frost, which used to be May 15, now occurs in mid-April. The first frost of the season varies widely. In 2022, it was Nov. 30. This year, it was Oct. 28 in my East Wenatchee garden.
The longer growing season would encourage us to grow figs, sweet potatoes and okra, and other Southern delights. But not so fast. There are more frost-free days, but growing temperatures have not increased as much as we could anticipate.
This year, the day and night temperatures remained cool, so my garden soil did not reach 70 degrees — the optimal temperature for vegetable seed germination — until May 17. Then, the nighttime temperatures fell below 60 as early as August 19. This affected the growing of tomatoes. Tomatoes are so fussy that they only want to thrive and produce fruit in the narrow range of 60 to 86 degrees.
Another downside was disappointment for the little gang of backyard fig growers in the greater Wenatchee area. The earlier cooler nights stymied the ripening of the figs the past two years.
These are my personal observations from my gardening journal. Can you tell that my father was a meteorologist?
The next big change is the precipitation. In the early 2000s, we still received 9 inches of snow/rain for the year. As I write this on Nov. 1, our total precipitation for the year has been 4.18 inches. All that snow we had last winter evaporated rather than melting and soaking into the soil. The soil in areas not regularly irrigated is very dry.
We need to consider what we plant in our landscapes. Dogwood and beech tree leaves will be more summer-crisped than ever. Plants need to be more drought tolerant.
Select new plants that have an American Horticulture Society heat zone rating of 7 because we have had an increasing number of days each year where the temperature is above 86 degrees.
Mike Hammer shared this information with his fellow WSU Chelan-Douglas Master Gardener volunteers earlier this year:
- From 1994-2003: we had 13 days over 95 degrees and 31 days over 90 degrees.
- From 2004-2013: we had 16 days over 95 degrees and 33 days over 90 degrees.
- From 2014 -2023: we had 24 days over 95 degrees and 45 days over 90 degrees.
Note: Information is from the WSU AgWeatherNet station at the WSU Tree Fruit Research and Extension Center in Wenatchee.
The heat affects the growth of lawns and many garden plants, especially tomatoes and blueberries. It is now more important to use mulches to preserve the soil moisture and keep the soil cool. Lawns should be cut 2 1/2 to 3 inches high to prevent the grass crowns from being damaged by the heat — more water will not protect the crowns.
We receive little precipitation during the frost-free six months. Irrigation in home gardens needs to be run less often and for longer periods of time to ensure that the water reaches the plants’ roots. The days of the ineffective practice of 10 minutes of water twice a day are long gone. Email the Master Gardeners at chelanmastergardeners@gmail.com for advice for effective turf watering.
Changing irrigation practice is only one way to garden more effectively with increased heat and drought. Placement of plants close together and applying 3 to 4 inches of mulch will keep the garden areas more productive.
Start planning your new, improved garden now.
A WSU Chelan and Douglas County Master Gardener column appears weekly in The Wenatchee World. To learn more, visit bit.ly/MGchelandouglas or call (509) 667-6540.