Planting Evergreens & Conifers in Willamette Valley’s Winter

Confiers in Oregon

The Willamette Valley, with its unique climate and growing conditions, offers an excellent environment for growing evergreen trees. Our region, characterized by mild, wet winters and warm, dry summers, provides for wonderful conditions for growing. Let's explore some suitable evergreen trees for this area and provide tips for successful cultivation.

Our Favorite Evergreens in our Willamette Valley Nursery

  1. Blue Spruce (Picea pungens): Known for its striking blue-grey needles and pyramidal shape, is a popular choice in the Pacific Northwest due to its hardiness and adaptability to various soil types. This tree thrives in the region's cool, moist climate, and its dense foliage provides excellent windbreaks and privacy screens.
  2. Incense Cedar (Calocedrus decurrens): Distinguished by its aromatic wood, bright green, scale-like leaves, and narrow, conical growth habit. It's well-suited to the Pacific Northwest's environment, as it prefers moist, well-drained soils and tolerates both shade and sun. This cedar is also resistant to many of the diseases that commonly affect other conifers in this region.
  3. Vanderwolf's Pyramid Pine (Pinus flexilis): Notable for its unique, twisted blue-green needles and a distinct pyramidal shape. It is a hardy tree that does well in the Pacific Northwest, thriving in both the cold winters and the moderate summers. Its ability to adapt to various soil conditions and its resistance to drought make it a versatile choice for landscaping in this area.
  4. Emerald Green Arborvitae (Thuja occidentalis 'Smaragd'): Popular evergreen with a narrow, upright growth habit and bright, emerald green foliage that stays vibrant year-round. It is particularly well-suited to the Pacific Northwest due to its tolerance for wet conditions. This tree is often used for hedges and privacy screens due to its dense growth.

Why Plant Evergreens and Conifers in the Winter

Planting evergreens in Oregon during the Winter can be quite successful due to several key factors related to the region's climate and soil conditions:

  1. Mild Winter Temperatures: Unlike many other regions, Oregon, especially the Willamette Valley, experiences relatively mild winters. The temperatures seldom drop to extreme lows that would freeze the soil deeply. This means that the ground remains workable, and the roots of evergreens can still establish themselves even during the winter months.
  2. Insulating Effect of Soil: Soil, particularly when it's moist, has insulating properties that help to moderate the temperature fluctuations. In Oregon, the frequent rains and overall soil moisture help to keep the soil at a relatively stable temperature, which is conducive to root growth.
  3. Reduced Plant Stress: During the colder months, evergreens are largely dormant, meaning their growth and metabolic processes have slowed down. Planting them in this dormant state reduces the stress on the plants, as they don't need to simultaneously establish roots and support new top growth.
  4. Early Root Establishment: Planting in January gives the trees a chance to start establishing their root systems before the onset of spring. When the warmer temperatures and longer daylight hours of spring arrive, the trees will be ready to grow more vigorously, having settled in during the winter.
  5. Moisture Availability: Oregon winters are typically wet, providing ample moisture for newly planted trees. This natural irrigation reduces the need for supplemental watering and helps the trees to establish their root systems.
  6. Preparation for Summer: By establishing their root systems in the cooler months, evergreens are better prepared for the dry, warmer summer. This early establishment can be crucial for their survival and health, especially in areas that experience significant summer drought.

The combination of mild winter temperatures, soil insulation properties, reduced plant stress during dormancy, early root establishment, ample moisture, and preparation for summer conditions makes Winter an ideal time for planting evergreens in Oregon.

Soil Preparation in the Willamette Valley:

  • Soil Type and Drainage: Most evergreens thrive in well-drained, acidic soils, typical of the valley. Ensure proper drainage to prevent root rot.
  • Soil pH: The naturally acidic soils of the region usually suit evergreens well, but a soil test can help in adjusting pH if necessary.
  • Organic Amendments: Enhance soil fertility and structure with organic matter like compost, especially important in areas with heavy clay soils.

Acclimatizing Evergreens in Oregon:

  • Choose Adapted Species: When selecting evergreens for Oregon landscapes, it's crucial to pick species that are either native to the region or have shown a strong ability to thrive in the region's unique climate. This includes considering factors like tolerance to the region's winter cold, resistance to local pests and diseases, and the ability to cope with the wet winters and dry summers typical across Oregon. Examples of such trees include the Douglas Fir, Western Red Cedar, and Oregon White Oak, each known for its resilience and adaptability to the local climate.
  • Planting Technique: Proper planting is key to the successful establishment of evergreens. Begin by digging a hole that is as deep as the root ball but two to three times wider. This helps the roots spread easily in the soil. When backfilling the hole, do it gently and avoid compacting the soil, which can impede root growth. After placing the tree, water it thoroughly to settle the soil and eliminate air pockets. Staking may be necessary for taller trees to provide stability until the roots are established.
  • Mulching and Watering: Mulching is a beneficial practice for evergreens, especially in Oregon's variable climate. A layer of organic mulch, like bark chips or leaf mold, around the base of the tree (but not touching the trunk) can help retain soil moisture, regulate soil temperature, and reduce weed competition. While Oregon's winters provide ample moisture, the dry summer months can stress young trees. It's essential to provide consistent and adequate watering during this period, especially in the first few years after planting, to ensure deep root development. Watering should be deep and infrequent rather than shallow and frequent, to encourage the roots to grow deeper into the soil.

By selecting the right evergreen species and adhering to these planting and care guidelines, gardeners in the Willamette Valley can enjoy the beauty and benefits of these trees. Enjoy these unique conditions of Oregon and watch your evergreens flourish in this diverse and fertile region.

Any questions? Call or stop by our nursery in Albany.  We’ll be happy to help you.

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