What is happening in our gardens this summer?
By Bonnie Orr
WSU Chelan/Douglas County Master Gardener
Spring starts with such promise. We can visualize the swaths of colorful perennials and annuals, the plump tomatoes, the tasty peas. The reality is different of course. Some people fear we live in a dangerous world of disease and insect infestations. That is not reality either.
The WSU Chelan-Douglas Master Gardeners meet dozens of people either in clinic at the Wenatchee Public Library on Mondays from 1 to 4 p.m. or via the questions we receive by email (askamastergardener@chelandouglasmg.org). The Third Saturday of the month at the Community Education Garden in Wenatchee is another place to ask for gardening advice.
We hear concerns about trees and shrubs, ornamentals, vegetables, weeds, insects, irrigation and lawns, always lots of questions about lawn care.
What causes most gardening problems are things we have no control over. We cannot change how hot, how windy or how dry the air and surrounding soil is.
Most of the gardening problems are abiotic causes. That is, it is often something you cannot control. The wind whips and tears leaves and causes some of them on the windy side of the plant to dehydrate and develop brown crispy edges. The heat — hey, it’s summer in North Central Washington, and we can expect a number of days of 90 and 100 degrees — is a big factor. Shade cloth can only lower the temperature a few degrees. It usually does not lower the soil temperature.
Plants are physiologically set to draw up water to keep leaves hydrated. With wind and heat, the plant cannot draw up enough water, so extreme wilting and dead leaves result. Applying more water to the plant only causes the roots to rot. Growing plants that are more heat resistant is the only way to solve these problems.
Weeds steal sunlight and moisture from your garden plants. If weeding is not one of your delights, you can get ahead by using mulch to prevent weeds from germinating, keep the ground cooler and slow evaporation from the soil. Mulch can be grass clippings or last year’s leaves — anything to create a barrier several inches deep. Gravel or rock often reflects heat on the plants and encourages the growth of weeds from seeds deposited by the wind between the rocks.
In May and June, we heard lots about powdery mildew on roses and peonies. Generally, mildew only causes cosmetic damage and does not kill the plant. After the high temperatures climbed into the 90s, the mildew went away. Growing mildew-resistant plants and cleaning up dead leaves in the fall will help reign in some of the mildew damage.
Most lawn weeds such as oxalis and spurge and crabgrass appear because a pre-emergent was not applied in a timely manner. When the soil is 50 degrees, a crabgrass preventer is applied. Oxalis and spurge appear when the soil is more than 60 degrees so pre-emergents for these weeds are applied later in the season.
Overall, lawn problems and dying shrubs and ornamentals are related to irrigation problems not disease nor insects. Drip irrigation has to be inspected every few weeks to be sure the water is being emitted and emitted at the roots, not the base of the tree or the shrub.
We have been giving away lots of empty tuna and pet food cans so people can measure the amount of water that is actually reaching the desired plants or section of the lawn. Many times, we have found that the distribution of the water is not as even as the gardener hopes it will be.
Contact us to identify insects — before you kill them. Roughly 95% of the insects and bugs are good guys. We can identify weeds and help you manage them. Don’t despair, you will still have lots of tomatoes!
A WSU Chelan Douglas Master Gardener column appears weekly in The Wenatchee World. To learn more, visit bit.ly/MGchelandouglas or call (509) 667-6540.