General Gardening Information

Program Contact: Master Gardeners
(509) 667-6540 • chelanmastergardeners@gmail.com

Weather and soil conditions east of the Cascades are important factors to consider when choosing and maintaining trees, shrubs, vegetables and flowers. Residents new to the arid climate, high summer heat, and generally low organic matter in the soil will find more success growing plants when aware of these conditions. An array of plants, such as tomatoes and melons, benefit from the heat. Even with careful placement, a favored dogwood risks an appearance marred by leaves scorched by hot sun and dry heat.

Take these conditions into account when designing a landscape and garden, and choosing and maintaining plants.

Average Temperatures

  • Wenatchee: Summer high- above 100°F’ / Winter low- min. -15°F /
  • Wenatchee: Average first frost date: Oct. 30 / Safe date for spring planting: Mother’s Day
  • Leavenworth: Summer night average: below 65°F
  • Leavenworth: Average first frost date: Sept. 18 /Safe date for spring planting: May 30

Annual precipitation (rain and snow)

  • Wenatchee 8-11 inches
  • Chelan 10-15 inches
  • Cashmere 8-12 inches
  • Leavenworth 15-25 inches
  • Humidity: low

Growing season

  • Wenatchee- average 119 days

USDA Hardiness zone

  •  Wenatchee – near the river: 7a (min. 0°F). Higher elevations, Chelan and Leavenworth tending to zone 6a – 6b (min. -5°F to -10°F)

American Horticultural Society Heat Zone

(Number of days above 86°F)

  • Wenatchee & Chelan: zone 6 (45-60 days)
  • Leavenworth: zone 5 (30-45 days)

Sunset Western Garden zone

  • Wenatchee & Chelan: 3B
  • Leavenworth: 1A

Wind

  • abundant in spring and summer (can be drying)

Soil

  • pH 7.0- (neutral tending to alkaline)
  • High in organic matter in forested areas. Common in Leavenworth
  • Low in organic matter and water holding capacity in silt, sand and clay, common in Wenatchee
  • Soil composition varies – majority is silt and sand but can have pockets of clay
  • Erosion – during acute rain and wind storms

Plants

  • Heavy snow and wind can break branches of flowering dogwood, Japanese maples, Austrian Black Pine, Scotch Pine (trees and shrubs with brittle wood)
  • Drying, hot summer winds can cause leaf scorch on dogwood trees and Japanese maples not protected by taller trees
  • More summer heat benefits melons, squashes, pit fruits, tomatoes, beans
  • More conifers and broadleaf deciduous trees
  • Smaller range of insects and diseases – probably from winter kill

Maintenance

  • Lawns: must provide water in the summer
  • Group plants of similar water demands, and water by irrigation zones

Washington State University