When to Plant Watercress in Ketchikan Gateway Borough, AK
May in the garden — Ketchikan Gateway Borough, Alaska
May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Ketchikan Gateway Borough, Alaska.
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Start watercress under lights
A seed-starting mix and a sunny window (or a grow light) are all you need. Keep soil warm — around 70°F — for fast germination.
June prep starts now
- First harvests: watercress
Watercress is a semi-aquatic plant with a peppery, tangy flavor rich in vitamins and minerals. It grows naturally along streams and can be cultivated in containers with standing water.
Ketchikan Gateway Borough, Alaska is in USDA Zone 7b. The average last spring frost is April 25 and the first fall frost is October 19, giving you a growing season of approximately 177 days.
At an elevation of 1,212 feet, Ketchikan Gateway Borough receives approximately 57.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 65°F, so choose short-season varieties of Watercress to ensure they mature before fall. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Watercress root diseases.
Ketchikan Gateway Borough Soil Profile
Soil Type
Silt Loam
Soil pH
5-6.7
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 Ketchikan Gateway Borough
How your county's soil matches Watercress's growing requirements.
Soil pH
Your soil pH (5.0–6.7) is more acidic than Watercress prefers (6.5–7.5). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Ketchikan Gateway Borough is excellent for Watercress — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Watercress.
Organic Matter
Organic matter is excellent (5.9%) — Watercress will thrive.
How to Plant Watercress
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Watercress
Sow every 4.6 weeks. Last sowing by Aug 20 to harvest before frost.
For a dedicated fall crop, sow by Aug 10.
Plant Water Budget
Monthly Watering Guide for Watercress
Watercress needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.
| Month | Watercress Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 2.8" | 0" | ❄️ Dormant |
| Feb | — | 2.6" | 0" | ❄️ Dormant |
| Mar | — | 1.8" | 0" | ❄️ Dormant |
| Apr | 6.5" | 2" | 4.5" | 🚿 Regular watering |
| May | 6.5" | 2.4" | 4.1" | 🚿 Regular watering |
| Jun | 6.5" | 4.5" | 2" | 💧 Light watering |
| Jul | 6.5" | 6.6" | 0" | ✅ Rainfall sufficient |
| Aug | 6.5" | 9.5" | 0" | ✅ Rainfall sufficient |
| Sep | 6.5" | 11" | 0" | ✅ Rainfall sufficient |
| Oct | 6.5" | 6.6" | 0" | ✅ Rainfall sufficient |
| Nov | — | 3.8" | 0" | ❄️ Dormant |
| Dec | — | 3.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Ketchikan Gateway Borough). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Watercress 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.
Watercress Planting Timeline — Ketchikan Gateway Borough, AK
Watercress Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 21 | Mar 21 – Apr 4 |
| Transplant Outdoors | April 25 | Apr 25 – May 9 |
| Direct Sow | April 11 | Apr 11 – May 2 |
| Harvest | June 6 | Jun 6 – Jul 11 |
| Fall Sowing | August 10 | Aug 10 – Aug 24 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors Transplant Outdoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | Harvest |
| July | Harvest |
| August | Fall Sowing |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
1.5"/week · Natural rainfall sufficient
📅 Days to Maturity
40–60 days
🧪 Soil pH
Needs 6.5–7.5 · Your soil: too_acidic
🗺️ USDA Zone
Zone 7b
📆 Growing Season
177 days in Ketchikan Gateway Borough
Growing Tips for Watercress in Ketchikan Gateway Borough
Direct sow Watercress outdoors after April 25 in Ketchikan Gateway Borough when soil has warmed and frost danger has passed.
Your generous 177.0-day season in Ketchikan Gateway Borough allows multiple plantings of Watercress. Sow every 20.0 days for continuous harvest.
Common pests for Watercress in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.
General growing tips
Grow in containers with trays of water kept fresh. Provide partial shade and cool conditions. Harvest stems by cutting above water level. Replace water frequently to prevent stagnation.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Watercress in Other Locations
Frequently Asked Questions
When should I plant Watercress in Ketchikan Gateway Borough, AK?
Ketchikan Gateway Borough is in Zone 7b with an average last frost of April 25. Plan your Watercress planting based on this frost date — see the calendar above for exact timing.
What planting zone is Ketchikan Gateway Borough, AK?
Ketchikan Gateway Borough, Alaska is in USDA Hardiness Zone 7b. The average last spring frost is April 25 and first fall frost is October 19.
Your Ketchikan Gateway Borough Garden Planner — Free
A 24-page printable planner built for Ketchikan Gateway 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.