When to Plant Mulberries in Petersburg Borough, AK
What to do in May
May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Petersburg Borough, Alaska.
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Time to transplant mulberries
Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.
Mulberries are fast-growing, long-lived trees that produce abundant sweet-tart berries over an extended harvest period. The berries resemble elongated blackberries.
Petersburg Borough, Alaska is in USDA Zone 7b. The average last spring frost is April 23 and the first fall frost is October 20, giving you a growing season of approximately 180 days.
At an elevation of 974 feet, Petersburg Borough receives approximately 17.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 57°F, so choose short-season varieties of Mulberries to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Mulberries successfully. Mulch heavily to conserve soil moisture.
Petersburg Borough Soil Profile
Soil Type
Silt Loam
Soil pH
4.9-6.3
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 Petersburg Borough
How your county's soil matches Mulberries's growing requirements.
Soil pH
Your soil pH (4.9–6.3) overlaps with Mulberries's range (5.5–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Petersburg Borough is excellent for Mulberries — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Mulberries.
Organic Matter
Organic matter is excellent (6.8%) — Mulberries will thrive.
How to Plant Mulberries
Plant Water Budget
Monthly Watering Guide for Mulberries
Mulberries needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Mulberries Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 0.9" | 0" | ❄️ Dormant |
| Feb | — | 0.9" | 0" | ❄️ Dormant |
| Mar | — | 0.7" | 0" | ❄️ Dormant |
| Apr | 4.3" | 0.5" | 3.8" | 🚿 Regular watering |
| May | 4.3" | 0.7" | 3.6" | 🚿 Regular watering |
| Jun | 4.3" | 1.2" | 3.1" | 🚿 Regular watering |
| Jul | 4.3" | 2" | 2.3" | 🚿 Regular watering |
| Aug | 4.3" | 2.5" | 1.8" | 💧 Light watering |
| Sep | 4.3" | 2.9" | 1.4" | 💧 Light watering |
| Oct | 4.3" | 2.6" | 1.7" | 💧 Light watering |
| Nov | — | 1.4" | 0" | ❄️ Dormant |
| Dec | — | 1.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Petersburg Borough). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Mulberries 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.
Mulberries Planting Timeline — Petersburg Borough, AK
Mulberries Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | May 14 | May 14 – May 28 |
· 120" apart · Rows 144" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Transplant Outdoors |
| June | — |
| July | — |
| August | — |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Only during dry spells
📅 Days to Maturity
730–1825 days
🧪 Soil pH
Needs 5.5–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 7b
📆 Growing Season
180 days in Petersburg Borough
Growing Tips for Mulberries in Petersburg Borough
Direct sow Mulberries outdoors after April 23 in Petersburg Borough when soil has warmed and frost danger has passed.
Your 180.0-day growing season in Petersburg Borough is tight for Mulberries (730.0-1825.0 days to maturity). Start indoors and choose early-maturing varieties.
Petersburg Borough receives only 17" of rain annually. Mulberries needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Plant away from driveways and patios as fallen berries stain. Minimal pruning is needed. Harvest by shaking branches over a tarp. Birds love mulberries so plant extra.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Mulberries in Other Locations
Frequently Asked Questions
When should I plant Mulberries in Petersburg Borough, AK?
Petersburg Borough is in Zone 7b with an average last frost of April 23. Plan your Mulberries planting based on this frost date — see the calendar above for exact timing.
What planting zone is Petersburg Borough, AK?
Petersburg Borough, Alaska is in USDA Hardiness Zone 7b. The average last spring frost is April 23 and first fall frost is October 20.
Your Petersburg Borough Garden Planner — Free
A 24-page printable planner built for Petersburg Borough (Zone 7b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.