Red tomatoes

Best Planting Times for Tomatoes in Washington

Planting MethodActivityRecommended Dates
Outdoor PlantingIndoor Seed StartingMarch 1 – April 1
Transplant OutdoorsMay 1 – May 31
Greenhouse PlantingYear-roundAdjust planting based on temperature control in the greenhouse

Planting Conditions

Washington State has a diverse climate, with the western part experiencing a marine climate, characterized by mild, wet winters and cool summers, while the eastern part is more arid and continental. The state falls within USDA Hardiness Zones 4b to 9a, requiring different strategies depending on the region.

Sun Requirements

Tomatoes in Washington require full sun, needing at least 6-8 hours of direct sunlight each day. In the western part of the state, ensuring tomatoes receive adequate sunlight is crucial due to often cloudy conditions.

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Useful Tools for Starting Tomatoes Indoors

Using the right tools can save you time and increase your success rate.

Seeds

Quality seeds lead to better germination and healthier plants. Starting with high-quality seeds gives your tomatoes the best chance to thrive from the very beginning.
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Browse Tomato Seeds on Amazon

Planting Trays

Planting trays help you organize your seedlings and ensure they have enough space to grow before you transplant them outdoors. This makes the process more efficient and increases the chances of strong, healthy plants.
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Grow Lights

Grow lights are essential if you don’t have enough natural sunlight. They provide your seedlings with the light they need to grow strong and healthy, even in less-than-ideal conditions.
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Seed Starting Soil

Using light, fine soil specifically designed for seed starting helps young roots establish quickly and promotes healthy growth. It’s an easy way to give your seedlings the best start possible.
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Greenhouse Growing

In Washington, where the climate can be rainy and cool, a greenhouse is ideal for protecting your tomato plants from excess moisture and cooler temperatures. It helps create a controlled environment that extends the growing season, ensuring a more consistent and bountiful harvest.

Currently, the 8x10x7.5 FT Greenhouse is priced at $999. It’s a great investment for ensuring your tomatoes thrive all year round.
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Check the latest price on Amazon.

Fertilizer

Fertilizer is essential to provide your tomato plants with the nutrients they need for strong growth and a successful harvest.
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Other planting guides for Washington:

Any questions on growing tomatoes? Visit our forum to discuss: Growing Tomatoes

Starting Tomatoes Indoors

In areas like Seattle (Zone 8b), start tomato seeds indoors from March 1 to April 1. This timing ensures that seedlings are ready for transplanting outdoors from early May, after the last frost has passed.

Transplanting Tomato Seedlings

Transplant seedlings outdoors from May 1 to May 31, when soil temperatures are consistently above 50°F. Space the seedlings 24-36 inches apart in rows at least 36 inches apart to ensure proper air circulation and sunlight exposure.

General Care and Maintenance

Watering:

  • Water deeply and consistently to maintain evenly moist soil. In western Washington, be mindful of excess moisture due to frequent rain, while in the drier eastern regions, more frequent watering may be necessary.
  • Water at the base of the plants to prevent wetting the foliage, reducing the risk of fungal diseases.

Fertilizing:

  • Apply a balanced fertilizer at planting and again when the first fruits begin to set. Adding compost to the soil before planting improves soil fertility and structure.

Pest and Disease Management:

  • Monitor for common pests like aphids, cutworms, and tomato hornworms. The humid conditions in some parts of Washington can also encourage fungal diseases.
  • Use organic or integrated pest management strategies to protect your plants from pests and diseases.

Harvesting Tomatoes:

  • Harvest tomatoes when they are fully colored and firm. Regular harvesting during Washington’s summer months helps maintain fruit quality and prevents overripening.
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