When to Plant Tomatoes in Bonneville County, ID
Top priorities for Bonneville County, Idaho gardeners in May
Here's what deserves your attention in Bonneville County, Idaho this month. Everything below is tailored to Zone 5b and timed around your local frost dates.
June prep starts now
- Transplants going out: tomatoes
- Direct-sowing: 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.
Bonneville County, Idaho is in USDA Zone 5b. The average last spring frost is May 26 and the first fall frost is September 19, giving you a growing season of approximately 116 days.
At an elevation of 7,993 feet, Bonneville County receives approximately 20.9 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Tomatoes during the growing season.
Bonneville County Soil Profile
Soil Type
Loam
Soil pH
6.5-8
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 Bonneville County
How your county's soil matches Tomatoes's growing requirements.
Soil pH
Your soil pH (6.5–8.0) is more alkaline than Tomatoes prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Bonneville County is excellent for Tomatoes — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.4%). Annual compost additions will help Tomatoes.
How to Plant Tomatoes
Succession Planting Tomatoes
Sow every 6.9 weeks. Last sowing by Jun 26 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 | — | 1.5" | 0" | ❄️ Dormant |
| Feb | — | 1.2" | 0" | ❄️ Dormant |
| Mar | — | 2" | 0" | ❄️ Dormant |
| Apr | — | 2.4" | 0" | ❄️ Dormant |
| May | 5.2" | 2.2" | 3" | 🚿 Regular watering |
| Jun | 5.2" | 1.7" | 3.5" | 🚿 Regular watering |
| Jul | 5.2" | 2.1" | 3.1" | 🚿 Regular watering |
| Aug | 5.2" | 1.9" | 3.3" | 🚿 Regular watering |
| Sep | 5.2" | 1.7" | 3.5" | 🚿 Regular watering |
| Oct | — | 1.9" | 0" | ❄️ Dormant |
| Nov | — | 1.4" | 0" | ❄️ Dormant |
| Dec | — | 1.1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Bonneville 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 — Bonneville County, ID
Tomatoes Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 31 | Mar 31 – Apr 14 |
| Transplant Outdoors | June 9 | Jun 9 – Jun 23 |
| Direct Sow | June 2 | Jun 2 – Jun 23 |
| Harvest | August 11 | Aug 11 – Oct 20 |
Plant 0.5" deep · 24" apart · Rows 36" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors |
| May | — |
| 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 · 1-2 times/week
📅 Days to Maturity
60–85 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 5b
📆 Growing Season
116 days in Bonneville County
Growing Tips for Tomatoes in Bonneville County
Direct sow Tomatoes outdoors after May 26 in Bonneville 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.
Bonneville County receives only 21" 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 Bonneville 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 Bonneville County, ID?
Bonneville County is in Zone 5b with an average last frost of May 26. Plan your Tomatoes planting based on this frost date — see the calendar above for exact timing.
What planting zone is Bonneville County, ID?
Bonneville County, Idaho is in USDA Hardiness Zone 5b. The average last spring frost is May 26 and first fall frost is September 19.
Your Bonneville County Garden Planner — Free
A 24-page printable planner built for Bonneville 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.