Eastern WA Garden

Plant Hardiness and Care in Different Climates

The plant hardiness and growing conditions in Eastern Washington, Seattle, WA, and Bend, OR, vary significantly due to their distinct climatic zones. Based on the USDA Plant Hardiness Zone Map, which is a standard for determining where plants are most likely to thrive based on the average annual extreme minimum winter temperature​​, we can compare these regions:

This area spans from USDA Zone 4b to 9a​​. It experiences a continental climate with extreme temperature fluctuations, including hot summers and cold winters. This climate demands plants that can withstand both intense heat and significant cold.

Compared to these cities...

• Seattle, WA: Located in Zones 9a and 9b​​, Seattle enjoys a milder, wet maritime climate with less extreme temperature variations than Eastern Washington. Plants in this area need to adapt to more humidity and consistent moisture levels.

• Bend, OR: This region is in Zone 6b, characterized by a high desert climate. It has cooler summers and cold winters, but less extreme than Eastern Washington. Plants here must be adaptable to cooler summer temperatures and dry conditions.

Eastern Washington presents a markedly different climate compared to Western Washington, primarily due to the Cascade Range which acts as a climatic barrier. This geographical feature results in Eastern Washington experiencing a continental climate, characterized by hot summers and cold winters, in contrast to the maritime climate of Western Washington which is milder and more humid.

Eastern Washington's continental climate, with its extremes of hot summers and cold winters, contrasts sharply with Seattle's milder, maritime climate and Bend's high desert conditions. 

This diversity significantly affects the cultivation and care of various plants, including vinca, mint, dusty miller, roses, lavender, and Russian sage. Each plant's specific needs in terms of soil, sunlight, pruning, fertilization, hardiness, and watering must be considered in these distinct climates.

Vinca (Vinca minor)

• Care: Requires well-drained soil, tolerates full sun to partial shade, needs minimal pruning, light spring fertilization, and weekly watering in dry conditions.

• Soil: Prefers well-drained, loamy soil.

• Sunlight: Tolerates full sun to partial shade.

• Pruning: Minimal pruning needed, mainly to control spread.

• Fertilization: Light fertilization in spring.

• Hardiness: USDA Zones 4-9; withstands -30°F.

• Watering: Drought-tolerant; weekly watering recommended.

• Survival Mechanism: Vinca, also known as periwinkle, is a robust ground cover plant. Its survival in winter is attributed to its evergreen foliage and deep root system, which provide insulation against freezing temperatures.

• Adaptation: It adapts well to a variety of soil types, though it prefers well-drained soils. Vinca's resilience is enhanced in sheltered areas or when mulched to protect roots from extreme cold.

Mint (Mentha spp.)

• Care: Prefers consistently moist, well-drained soil, full sun to partial shade, requires regular pruning, moderate fertilization, and consistent moisture.

• Soil: Prefers moist, well-drained soil; tolerates a range.

• Sunlight: Full sun to partial shade.

• Pruning: Regular pruning to promote bushy growth.

• Fertilization: Moderate, especially if leaves are harvested often.

• Hardiness: USDA Zones 3-8; endures -40°F.

• Watering: Needs consistent moisture.

• Survival Mechanism: Mint is a hardy perennial herb known for its vigorous growth and ability to withstand harsh conditions. Its underground rhizomes are key to its survival during winter, as they can endure freezing temperatures and regrow in spring.

• Adaptation: Mint benefits from mulching for extra insulation during winter. It prefers moist, well-drained soils and can thrive in both sun and partial shade.

Lavender (Lavandula spp.)

• Care: Prefers well-drained, slightly alkaline soil, full sun, early spring and post-flowering pruning, low fertilization, and water once or twice a week (drought-tolerant).

• Soil: Prefers well-drained, slightly alkaline soil.

• Sunlight: Full sun is essential.

• Pruning: Prune early spring and after flowering.

• Fertilization: Low; too much can inhibit flowering.

• Hardiness: USDA Zones 5-9; tolerates -20°F.

• Watering: Drought-tolerant; water once or twice a week.

• Survival Mechanism: Lavender is a perennial that can survive winter with its woody stems and evergreen foliage. It's particularly resistant to cold when established and mature.

• Adaptation: Requires well-drained soil and full sun. In wetter, colder parts of Eastern Washington, raised beds or gravelly soil can aid in winter survival.

Roses (Rosa spp.)

• Care: Requires rich, well-drained loamy soil, full sun, regular pruning, regular feeding during growing season, and deep, infrequent watering.

• Soil: Rich, well-drained loamy soil.

• Sunlight: Requires full sun.

• Pruning: Regular pruning essential for health and bloom.

• Fertilization: Regular feeding during growing season.

• Hardiness: Varies; most hardy to -20°F (USDA Zones 3-11).

• Watering: Requires deep, infrequent watering.

• Survival Mechanism: Roses, particularly shrub and old garden varieties, can endure cold winters. Their hardiness is often dependent on the rootstock and variety.

• Adaptation: Proper winter care, including mulching around the base and pruning, is crucial. Some varieties may need additional protection, like burlap wraps, in extremely cold zones.

Dusty Miller (Senecio cineraria)

• Care: Needs well-drained soil, thrives in full sun, minimal pruning, light feeding, and water sparingly (drought-tolerant).

• Soil: Well-drained, not too rich.

• Sunlight: Prefers full sun.

• Pruning: Prune lightly to maintain shape.

• Fertilization: Light feeding; too much can reduce silver foliage.

• Hardiness: USDA Zones 7-10; tolerates light frost.

• Watering: Drought-tolerant; water sparingly.

• Survival Mechanism: While often grown as an annual in colder climates, dusty miller can survive mild winters in Eastern Washington. Its silvery-gray foliage is somewhat frost-resistant, but the plant may need protection in extreme cold.

• Adaptation: Well-drained soil and sunny locations enhance its winter survival. In the colder parts of the region, it may require shelter or mulching.

Russian Sage (Perovskia atriplicifolia)

• Care: Thrives in poor, well-drained soils, requires full sun, early spring pruning, minimal fertilization, and infrequent watering (extremely drought-tolerant).

• Soil: Thrives in poor, well-drained soils.

• Sunlight: Full sun required.

• Pruning: Cut back in early spring.

• Fertilization: Minimal; over-fertilization can lead to floppy growth.

• Hardiness: USDA Zones 4-9; withstands -30°F.

• Watering: Extremely drought-tolerant; infrequent watering needed.

• Survival Mechanism: Russian sage, with its woody stems and aromatic leaves, is well-suited to withstand cold. It dies back to the ground in winter but regrows from its roots in spring.

• Adaptation: Prefers dry, well-drained soils and full sun. It's drought-tolerant, making it well-suited to Eastern Washington's climate.

Understanding the specific needs of each plant in relation to the local climate is crucial. 

For example, in Eastern Washington, plants like vinca, dusty miller, lavender, and Russian sage are ideal for xeriscaping due to their drought tolerance. 

Conversely, in the more humid climate of Seattle, plants such as mint and roses, which require consistent moisture, may fare better. 

In Bend's high desert environment, drought-tolerant plants like lavender and Russian sage would be suitable, whereas plants requiring more moisture might need additional care.