When to Plant Tomatoes in Blaine County, ID
What to do in May
May is a pivotal month for Blaine County, Idaho gardens. Focus on these tasks first and you'll set up the rest of the season for success.
-
Direct-sow tomatoes
Your soil is 35°F — warm enough for these to germinate without babying.
To set up a strong June, finish these tasks
- Transplants going out: 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.
Blaine County, Idaho is in USDA Zone 5b. The average last spring frost is May 18 and the first fall frost is October 3, giving you a growing season of approximately 138 days.
At an elevation of 7,128 feet, Blaine County receives approximately 17.7 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Tomatoes to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Tomatoes successfully. Mulch heavily to conserve soil moisture.
Blaine County Soil Profile
Soil Type
Loam
Soil pH
6.7-8.4
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 Blaine County
How your county's soil matches Tomatoes's growing requirements.
Soil pH
Your soil pH (6.7–8.4) is more alkaline than Tomatoes prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Blaine County is excellent for Tomatoes — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Tomatoes.
Organic Matter
Organic matter is moderate (2.2%). Annual compost additions will help Tomatoes.
How to Plant Tomatoes
Succession Planting Tomatoes
Sow every 6.9 weeks. Last sowing by Jul 10 to harvest before frost.
Plant Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
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 | — | 1.4" | 0" | ❄️ Dormant |
| Feb | — | 0.9" | 0" | ❄️ Dormant |
| Mar | — | 1.5" | 0" | ❄️ Dormant |
| Apr | — | 1.7" | 0" | ❄️ Dormant |
| May | 5.2" | 1.9" | 3.3" | 🚿 Regular watering |
| Jun | 5.2" | 1.2" | 4" | 🚿 Regular watering |
| Jul | 5.2" | 1.8" | 3.4" | 🚿 Regular watering |
| Aug | 5.2" | 2.2" | 3" | 🚿 Regular watering |
| Sep | 5.2" | 1.5" | 3.7" | 🚿 Regular watering |
| Oct | 5.2" | 1.4" | 3.8" | 🚿 Regular watering |
| Nov | — | 1.3" | 0" | ❄️ Dormant |
| Dec | — | 1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Blaine 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 — Blaine County, ID
Tomatoes Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 23 | Mar 23 – Apr 6 |
| Transplant Outdoors | June 1 | Jun 1 – Jun 15 |
| Direct Sow | May 25 | May 25 – Jun 15 |
| Harvest | August 3 | Aug 3 – Oct 12 |
Plant 0.5" deep · 24" apart · Rows 36" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors |
| May | Direct Sow |
| June | Transplant Outdoors Direct Sow |
| July | — |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1.2"/week · 2-3 times/week
📅 Days to Maturity
60–85 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 5b
📆 Growing Season
138 days in Blaine County
Growing Tips for Tomatoes in Blaine County
Direct sow Tomatoes outdoors after May 18 in Blaine 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.
Blaine County receives only 18" of rain annually. Tomatoes needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
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 Blaine County
Choose determinate, early-maturing varieties for your short season
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 Blaine County, ID?
Blaine County is in Zone 5b with an average last frost of May 18. Plan your Tomatoes planting based on this frost date — see the calendar above for exact timing.
What planting zone is Blaine County, ID?
Blaine County, Idaho is in USDA Hardiness Zone 5b. The average last spring frost is May 18 and first fall frost is October 3.
Your Blaine County Garden Planner — Free
A 24-page printable planner built for Blaine County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.