When to Plant Tomatoes in Snohomish County, WA
Top priorities for Snohomish County, Washington gardeners in May
Here's what deserves your attention in Snohomish County, Washington this month. Everything below is tailored to Zone 8b and timed around your local frost dates.
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Time to start tomatoes inside
Your window is short. These crops want several weeks of indoor growth before they go outside.
To set up a strong June, finish these tasks
- First harvests: tomatoes
Tomatoes are the most popular home garden crop, available in thousands of varieties from tiny cherries to massive beefsteaks. They are warm-season plants needing full sun.
Snohomish County, Washington is in USDA Zone 8b. The average last spring frost is March 25 and the first fall frost is November 2, giving you a growing season of approximately 222 days.
At an elevation of 230 feet, Snohomish County receives approximately 50.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Tomatoes during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Tomatoes root diseases.
Snohomish County Soil Profile
Soil Type
Silt Loam
Soil pH
5.7-6.8
Drainage
Well Drained
Plant Planting Risk Windows
Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.
Soil Compatibility in Snohomish County
How your county's soil matches Tomatoes's growing requirements.
Soil pH
Your soil pH (5.7–6.8) overlaps with Tomatoes's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Snohomish County is excellent for Tomatoes — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (5.4%) — Tomatoes will thrive.
How to Plant Tomatoes
Succession Planting Tomatoes
Sow every 6.9 weeks. Last sowing by Aug 09 to harvest before frost.
Plant Water Budget
Monthly Watering Guide for Tomatoes
Tomatoes needs approximately 1.2 inches of water per week (5.2" per month). Here's how your county's rainfall compares month by month.
| Month | Tomatoes Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 7.7" | 0" | ❄️ Dormant |
| Feb | — | 5.6" | 0" | ❄️ Dormant |
| Mar | 5.2" | 5" | 0.2" | 💧 Light watering |
| Apr | 5.2" | 3.6" | 1.6" | 💧 Light watering |
| May | 5.2" | 2.6" | 2.6" | 🚿 Regular watering |
| Jun | 5.2" | 1.6" | 3.6" | 🚿 Regular watering |
| Jul | 5.2" | 0.7" | 4.5" | 🚿 Regular watering |
| Aug | 5.2" | 1" | 4.2" | 🚿 Regular watering |
| Sep | 5.2" | 2" | 3.2" | 🚿 Regular watering |
| Oct | 5.2" | 4.2" | 1" | 💧 Light watering |
| Nov | 5.2" | 8" | 0" | ✅ Rainfall sufficient |
| Dec | — | 8.5" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Snohomish County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Tomatoes Heat Requirements (GDD)
What are Growing Degree Days (GDD)?
Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.
Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.
Tomatoes Planting Timeline — Snohomish County, WA
Tomatoes Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 4 | Feb 4 – Feb 18 |
| Transplant Outdoors | April 8 | Apr 8 – Apr 22 |
| Direct Sow | April 1 | Apr 1 – Apr 22 |
| Harvest | June 10 | Jun 10 – Aug 19 |
Plant 0.5" deep · 24" apart · Rows 36" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | — |
| April | Transplant Outdoors Direct Sow |
| May | — |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1.2"/week · Only during dry spells
📅 Days to Maturity
60–85 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 8b
📆 Growing Season
222 days in Snohomish County
Growing Tips for Tomatoes in Snohomish County
Direct sow Tomatoes outdoors after March 25 in Snohomish County when soil has warmed and frost danger has passed.
Common pests for Tomatoes in this region include tomato hornworm and aphids. Use row covers early in the season and inspect plants weekly.
General growing tips
Start seeds indoors 6-8 weeks before last frost. Bury transplants deep to encourage rooting along the stem. Provide consistent moisture to prevent blossom end rot and cracking.
Recommended Tomatoes Varieties for Snohomish County
Disease-resistant varieties for your humid climate
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Isolate 25 ft between varieties for purity. Use open-pollinated varieties for true-to-type seeds.
Tomatoes in Other Locations
Frequently Asked Questions
When should I plant Tomatoes in Snohomish County, WA?
Snohomish County is in Zone 8b with an average last frost of March 25. Plan your Tomatoes planting based on this frost date — see the calendar above for exact timing.
What planting zone is Snohomish County, WA?
Snohomish County, Washington is in USDA Hardiness Zone 8b. The average last spring frost is March 25 and first fall frost is November 2.
Your Snohomish County Garden Planner — Free
A 24-page printable planner built for Snohomish County (Zone 8b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.