When to plant Leeks in Jefferson County County,
Plant Leeks in Jefferson County County, when soil hits 50°F — usually May 8. Continue planting through May 29 for the spring crop. A second sowing from July 13 to July 27 extends the harvest into fall.
When to Plant Leeks in Jefferson County, ID
Your June planting checklist for Jefferson County, Idaho
June is a pivotal month for Jefferson County, Idaho gardens. Focus on these tasks first and you'll set up the rest of the season for success.
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Indoor seed-starting week for leeks
Starting these indoors now means sturdy transplants ready the moment your soil warms up.
Coming up in July — start thinking about
- Fall sowing: leeks
Leeks are a mild, sweet allium that produces long white shanks. They are more refined than onions and are a key ingredient in soups, stews, and gratins.
Jefferson County, Idaho is in USDA Zone 5a. The average last spring frost is May 22 and the first fall frost is September 21, giving you a growing season of approximately 122 days.
At an elevation of 5,094 feet, Jefferson County receives approximately 18 inches of rainfall annually with predominantly loam soil. Summer highs average 87°F, providing good warmth for Leeks during the growing season. With low rainfall, drip irrigation is essential for growing Leeks successfully. Mulch heavily to conserve soil moisture.
Jefferson County Soil Profile
Soil Type
Loam
Soil pH
6.3-7.8
Drainage
Well Drained
Leeks 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 Jefferson County
How your county's soil matches Leeks's growing requirements.
Soil pH
Your soil pH (6.3–7.8) is more alkaline than Leeks prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Jefferson County is excellent for Leeks — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.4%). Annual compost additions will help Leeks.
How to Plant Leeks
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Leeks Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Leeks
Leeks needs approximately 0.8 inches of water per week (3.5" per month). Here's how your county's rainfall compares month by month.
| Month | Leeks Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.1" | 0" | ❄️ Dormant |
| Feb | — | 1.2" | 0" | ❄️ Dormant |
| Mar | — | 1.4" | 0" | ❄️ Dormant |
| Apr | — | 2" | 0" | ❄️ Dormant |
| May | 3.5" | 1.9" | 1.6" | 💧 Light watering |
| Jun | 3.5" | 1.4" | 2.1" | 🚿 Regular watering |
| Jul | 3.5" | 1.4" | 2.1" | 🚿 Regular watering |
| Aug | 3.5" | 2" | 1.5" | 💧 Light watering |
| Sep | 3.5" | 1.6" | 1.9" | 🚿 Regular watering |
| Oct | — | 1.6" | 0" | ❄️ Dormant |
| Nov | — | 1.3" | 0" | ❄️ Dormant |
| Dec | — | 1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Jefferson County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Leeks 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.
Leeks Planting Timeline — Jefferson County, ID
Leeks Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 17 | Apr 17 – May 1 |
| Transplant Outdoors | May 22 | May 22 – Jun 5 |
| Direct Sow | May 8 | May 8 – May 29 |
| Harvest | August 21 | Aug 21 – Nov 6 |
| Fall Sowing | July 13 | Jul 13 – Jul 27 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | Start Indoors Transplant Outdoors Direct Sow |
| June | Transplant Outdoors |
| July | Fall Sowing |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | Harvest |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.8"/week · Only during dry spells
📅 Days to Maturity
90–150 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 5a
📆 Growing Season
122 days in Jefferson County
Growing Tips for Leeks in Jefferson County
Direct sow Leeks outdoors after May 22 in Jefferson County when soil has warmed and frost danger has passed.
Your 122.0-day growing season in Jefferson County is tight for Leeks (90.0-150.0 days to maturity). Start indoors and choose early-maturing varieties.
Common pests for Leeks in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.
General growing tips
Start seeds indoors 10-12 weeks before last frost. Transplant into trenches and hill soil around stems as they grow to increase the white portion. Harvest as needed.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Leeks in Other Locations
Frequently Asked Questions
When should I plant Leeks in Jefferson County, ID?
Jefferson County is in Zone 5a with an average last frost of May 22. Plan your Leeks planting based on this frost date — see the calendar above for exact timing.
What planting zone is Jefferson County, ID?
Jefferson County, Idaho is in USDA Hardiness Zone 5a. The average last spring frost is May 22 and first fall frost is September 21.
When should I plant Leeks in Jefferson County, ?
In Jefferson County, , plant Leeks after the last frost (around May 22) and before the first frost (around September 21). Best results when soil holds above 50°F.
What growing zone is Jefferson County, for Leeks?
Jefferson County sits in USDA Zone 5a. Leeks grows reliably in zones 3a through 10b, so it's a good fit here.
Can Leeks grow in Jefferson County's climate?
Yes — Leeks grows well in Jefferson County's temperate climate. Jefferson County averages a 122-day frost-free season, with last frost around May 22 and first frost around September 21.
Your Jefferson County Garden Planner — Free
A 22-page printable planner built for Jefferson County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.