June marks the start of the summer growing season across Washington State, shifting the gardener’s focus from frost avoidance to maximizing heat and available daylight. This month is a prime opportunity for planting warm-season crops that require high soil temperatures to thrive and is crucial for strategic succession planting. Taking advantage of the long days and warmer nights allows gardeners to establish their main summer harvest and plan for a productive fall. Success requires acknowledging the state’s geographical split, which dictates different planting strategies and crop selections.
June Planting Guide for Western Washington
Western Washington’s maritime climate is temperate, benefiting from cooler evenings and consistent soil moisture. June planting concentrates on establishing heat-loving plants and initiating the next wave of quick-maturing crops for a continuous summer harvest. This is the last safe window for transplanting warm-season vegetables requiring a long maturity period, such as tomatoes, peppers, and eggplants, ensuring they ripen before the autumn cool-down.
For direct sowing, bush beans are an excellent choice, as they germinate quickly in the warmer soil and produce a harvest in a concentrated period, making them ideal for small-space succession planting. Summer squash and cucumbers should also be sown directly into the ground now, especially short-season varieties, to avoid transplant shock and ensure a late-summer yield. Cucurbits prefer soil temperatures consistently above 60°F for optimal growth.
June is also the ideal time to sow seeds for a fall harvest of cool-season crops, maximizing the mild western climate. Direct sow carrots and beets, ensuring they have plenty of time to size up before shorter days slow their growth. Quick-maturing greens like Swiss chard and heat-tolerant lettuce should be planted in small, staggered batches every two to three weeks to prevent bolting and maintain a steady supply. For a winter yield, brassicas like broccoli and cabbage should be started from seed indoors or in a nursery bed by mid-month, preparing them for transplanting in July.
June Planting Guide for Eastern Washington
East of the Cascade Mountains, the continental climate features intense summer heat and high sun exposure. June planting centers on crops that relish extreme warmth and strategies to mitigate moisture loss. Soil temperature is typically well above the 60°F threshold, allowing for the immediate planting of demanding heat-lovers.
Melons (watermelons and cantaloupe) should be planted directly into the warm soil now, as they require significant heat and a long season to develop sugars. Planting from seed is generally preferred, but selecting short-season varieties is advisable to ensure ripeness before the first fall frost. Peppers and okra, which thrive in high heat, should be transplanted this month; okra only grows vigorously when soil temperatures are consistently high.
Managing water and sun stress is paramount for success. Deep, infrequent watering is more effective than light, daily sprinkling, encouraging the development of deep, resilient root systems. Applying a heavy layer of mulch conserves soil moisture and keeps the root zone cooler. When temperatures exceed 90°F, providing temporary afternoon shade with shade cloth can prevent sunscald on fruits and wilting on foliage.
Essential Herbs and Pollinator Flowers
June is the perfect time to establish herbs and flowers. Heat-loving herbs can be planted from transplants now to provide a summer-long supply.
Herbs that flourish in containers or well-drained garden beds include:
- Basil
- Rosemary
- Thyme
- Oregano
Planting colorful annuals in June ensures a vibrant display and attracts pollinators. Direct-sow seeds for cosmos and zinnias, which germinate readily and produce continuous blooms until frost. Marigolds and dahlias add bright color and attract pollinators like bees and butterflies, which maximize vegetable crop yields. Sunflowers are highly drought-tolerant and thrive in intense sun, serving as visual barriers and attracting diverse pollinators.