When to Plant Zinnia in Uintah County, UT
July to-do list for Uintah County, Utah
Here's what deserves your attention in Uintah County, Utah this month. Everything below is tailored to Zone 5b and timed around your local frost dates.
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Bring in the zinnia
This is the payoff month. Bring a basket, bring a friend, and get into the beds.
August will be here before you know it — start on
- First harvests: zinnia
Zinnia (Zinnia elegans) is a fast-growing, heat-loving annual that produces bold, dahlia-like blooms from early summer until hard frost. One of the easiest flowers to grow from direct-sown seed, zinnias thrive in hot, dry conditions and are magnets for butterflies and beneficial insects. They make excellent companion plants alongside marigolds in the vegetable garden.
Uintah County, Utah is in USDA Zone 5b. The average last spring frost is May 10 and the first fall frost is October 4, giving you a growing season of approximately 147 days.
At an elevation of 6,372 feet, Uintah County receives approximately 12.7 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Zinnia during the growing season. With low rainfall, drip irrigation is essential for growing Zinnia successfully. Mulch heavily to conserve soil moisture.
Uintah County Soil Profile
Soil Type
Loam
Soil pH
6.6-7.8
Drainage
Well Drained
Zinnia 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 Uintah County
How your county's soil matches Zinnia's growing requirements.
Soil pH
Your soil pH (6.6–7.8) overlaps with Zinnia's range (5.5–7.5), though not a perfect match.
Soil Texture
The loam soil in Uintah County is excellent for Zinnia — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Zinnia.
Organic Matter
Organic matter is moderate (2.5%). Annual compost additions will help Zinnia.
How to Plant Zinnia
Succession Planting Zinnia
Sow every 6.9 weeks. Last sowing by Jul 26 to harvest before frost.
Zinnia Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Zinnia
Zinnia needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.
| Month | Zinnia Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 0.9" | 0" | ❄️ Dormant |
| Feb | — | 0.7" | 0" | ❄️ Dormant |
| Mar | — | 1.2" | 0" | ❄️ Dormant |
| Apr | — | 1.2" | 0" | ❄️ Dormant |
| May | 2.2" | 1.5" | 0.7" | 💧 Light watering |
| Jun | 2.2" | 0.9" | 1.3" | 🚿 Regular watering |
| Jul | 2.2" | 1.2" | 1" | 💧 Light watering |
| Aug | 2.2" | 1.2" | 1" | 💧 Light watering |
| Sep | 2.2" | 1.1" | 1.1" | 🚿 Regular watering |
| Oct | 2.2" | 1.2" | 1" | 💧 Light watering |
| Nov | — | 0.9" | 0" | ❄️ Dormant |
| Dec | — | 0.7" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Uintah County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Zinnia 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.
Zinnia Planting Timeline — Uintah County, UT
Zinnia Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 12 | Apr 12 – Apr 26 |
| Transplant Outdoors | May 17 | May 17 – May 31 |
| Direct Sow | May 17 | May 17 – Jun 7 |
| Bloom | July 26 | Jul 26 – Oct 25 |
Plant 0.3" deep · 12" apart · Rows 18" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | Transplant Outdoors Direct Sow |
| June | Direct Sow |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · 1-2 times/week
📅 Days to Maturity
60–70 days
🧪 Soil pH
Needs 5.5–7.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 5b
📆 Growing Season
147 days in Uintah County
Growing Tips for Zinnia in Uintah County
Direct sow Zinnia outdoors after May 10 in Uintah County when soil has warmed and frost danger has passed.
Common pests for Zinnia in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.
Uintah County receives only 13" of rain annually. Zinnia needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Direct-sow after last frost when soil reaches 60°F; seeds germinate in 5-7 days. In zones 3-5 a brief indoor start (4 weeks) is worthwhile but transplant carefully — zinnias dislike root disturbance. Deadhead frequently to extend bloom. Excellent cut flower; harvesting regularly encourages branching. Avoid overhead watering to reduce powdery mildew.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Zinnia in Other Locations
Frequently Asked Questions
When should I plant Zinnia in Uintah County, UT?
Uintah County is in Zone 5b with an average last frost of May 10. Plan your Zinnia planting based on this frost date — see the calendar above for exact timing.
What planting zone is Uintah County, UT?
Uintah County, Utah is in USDA Hardiness Zone 5b. The average last spring frost is May 10 and first fall frost is October 4.
Your Uintah County Garden Planner — Free
A 22-page printable planner built for Uintah 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.