When to Plant Sweet Potatoes in Coconino County, AZ
Top priorities for Coconino County, Arizona gardeners in May
May is a pivotal month for Coconino County, Arizona gardens. Focus on these tasks first and you'll set up the rest of the season for success.
Coming up in June — start thinking about
- Transplants going out: sweet potatoes
- Direct-sowing: sweet potatoes
Sweet potatoes are a warm-season root crop that produces nutritious, sweet tubers in orange, white, and purple varieties. They need a long, hot growing season.
Coconino County, Arizona is in USDA Zone 7a. The average last spring frost is May 28 and the first fall frost is September 27, giving you a growing season of approximately 122 days.
At an elevation of 7,869 feet, Coconino County receives approximately 13.9 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 96°F, so Sweet Potatoes may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Sweet Potatoes will need more frequent watering and organic matter to retain nutrients. With low rainfall, drip irrigation is essential for growing Sweet Potatoes successfully. Mulch heavily to conserve soil moisture.
Coconino County Soil Profile
Soil Type
Sandy Loam
Soil pH
7.2-8.6
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 Coconino County
How your county's soil matches Sweet Potatoes's growing requirements.
Soil pH
Your soil pH (7.2–8.6) is more alkaline than Sweet Potatoes prefers (5.5–6.5). Add sulfur or peat moss to lower pH.
Soil Texture
Sandy soil in Coconino County warms quickly in spring but drains fast. Sweet Potatoes will need more frequent watering and regular compost additions to retain nutrients.
Drainage
Drainage is adequate for Sweet Potatoes.
Organic Matter
Organic matter is low (0.8%). Add 2-3 inches of compost before planting Sweet Potatoes.
How to Plant Sweet Potatoes
Plant Water Budget
Water stress score is 10/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Sweet Potatoes
Sweet Potatoes needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Sweet Potatoes Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1" | 0" | ❄️ Dormant |
| Feb | — | 0.7" | 0" | ❄️ Dormant |
| Mar | — | 0.8" | 0" | ❄️ Dormant |
| Apr | — | 0.4" | 0" | ❄️ Dormant |
| May | 4.3" | 0.3" | 4" | 🚿 Regular watering |
| Jun | 4.3" | 0.4" | 3.9" | 🚿 Regular watering |
| Jul | 4.3" | 2.6" | 1.7" | 💧 Light watering |
| Aug | 4.3" | 3" | 1.3" | 💧 Light watering |
| Sep | 4.3" | 1.7" | 2.6" | 🚿 Regular watering |
| Oct | — | 1.3" | 0" | ❄️ Dormant |
| Nov | — | 0.8" | 0" | ❄️ Dormant |
| Dec | — | 0.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Coconino County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Sweet Potatoes 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.
Sweet Potatoes Planting Timeline — Coconino County, AZ
Sweet Potatoes Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 9 | Apr 9 – Apr 23 |
| Transplant Outdoors | June 11 | Jun 11 – Jun 25 |
| Direct Sow | June 4 | Jun 4 – Jun 25 |
| Harvest | September 10 | Sep 10 – Oct 29 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | — |
| June | Transplant Outdoors Direct Sow |
| July | — |
| August | — |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · 2-3 times/week
📅 Days to Maturity
90–120 days
🧪 Soil pH
Needs 5.5–6.5 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 7a
📆 Growing Season
122 days in Coconino County
Growing Tips for Sweet Potatoes in Coconino County
Direct sow Sweet Potatoes outdoors after May 28 in Coconino County when soil has warmed and frost danger has passed.
Sandy soil in Coconino County dries quickly — mulch Sweet Potatoes with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.
With summer highs reaching 96°F in Coconino County, provide afternoon shade for Sweet Potatoes and water deeply in the morning.
Your 122.0-day growing season in Coconino County is tight for Sweet Potatoes (90.0-120.0 days to maturity). Start indoors and choose early-maturing varieties.
Coconino County receives only 14" of rain annually. Sweet Potatoes needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Plant slips (rooted sprouts) after soil is thoroughly warm. Build raised mounds for better root development. Cure harvested roots at 80-85F for 10 days to develop sweetness.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Sweet Potatoes in Other Locations
Frequently Asked Questions
When should I plant Sweet Potatoes in Coconino County, AZ?
Coconino County is in Zone 7a with an average last frost of May 28. Plan your Sweet Potatoes planting based on this frost date — see the calendar above for exact timing.
What planting zone is Coconino County, AZ?
Coconino County, Arizona is in USDA Hardiness Zone 7a. The average last spring frost is May 28 and first fall frost is September 27.
Your Coconino County Garden Planner — Free
A 24-page printable planner built for Coconino County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.