When to Plant Kai Lan in Columbia County, WA
Your May game plan for Columbia County, Washington
Here's what deserves your attention in Columbia County, Washington this month. Everything below is tailored to Zone 7a and timed around your local frost dates.
Coming up in June — start thinking about
- Starting indoors: kai lan
- First harvests: kai lan
Kai lan (Chinese broccoli) is a brassica grown for its thick, glossy stems and small flower buds. It has a slightly bitter, broccoli-like flavor essential in Cantonese cooking.
Columbia County, Washington is in USDA Zone 7a. The average last spring frost is April 28 and the first fall frost is October 11, giving you a growing season of approximately 166 days.
At an elevation of 3,157 feet, Columbia County receives approximately 21.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Kai Lan during the growing season.
Columbia County Soil Profile
Soil Type
Silt Loam
Soil pH
5.5-6.5
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 Columbia County
How your county's soil matches Kai Lan's growing requirements.
Soil pH
Your soil pH (5.5–6.5) overlaps with Kai Lan's range (6.0–7.5), though not a perfect match.
Soil Texture
The silt loam soil in Columbia County is excellent for Kai Lan — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.7%) — Kai Lan will thrive.
How to Plant Kai Lan
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Kai Lan
Sow every 5.1 weeks. Last sowing by Aug 12 to harvest before frost.
For a dedicated fall crop, sow by Aug 02.
Plant Water Budget
Monthly Watering Guide for Kai Lan
Kai Lan needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Kai Lan Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 3" | 0" | ❄️ Dormant |
| Feb | — | 2.6" | 0" | ❄️ Dormant |
| Mar | — | 2.1" | 0" | ❄️ Dormant |
| Apr | 4.3" | 1.7" | 2.6" | 🚿 Regular watering |
| May | 4.3" | 1.4" | 2.9" | 🚿 Regular watering |
| Jun | 4.3" | 0.9" | 3.4" | 🚿 Regular watering |
| Jul | 4.3" | 0.3" | 4" | 🚿 Regular watering |
| Aug | 4.3" | 0.3" | 4" | 🚿 Regular watering |
| Sep | 4.3" | 0.9" | 3.4" | 🚿 Regular watering |
| Oct | 4.3" | 1.9" | 2.4" | 🚿 Regular watering |
| Nov | — | 3" | 0" | ❄️ Dormant |
| Dec | — | 3.4" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Columbia County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Kai Lan 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.
Kai Lan Planting Timeline — Columbia County, WA
Kai Lan Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 24 | Mar 24 – Apr 7 |
| Transplant Outdoors | April 28 | Apr 28 – May 12 |
| Direct Sow | April 14 | Apr 14 – May 5 |
| Harvest | June 16 | Jun 16 – Jul 14 |
| Fall Sowing | August 2 | Aug 2 – Aug 16 |
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
Full Sun (6-8+ hours)
💧 Water
1"/week · 1-2 times/week
📅 Days to Maturity
45–60 days
🧪 Soil pH
Needs 6–7.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 7a
📆 Growing Season
166 days in Columbia County
Growing Tips for Kai Lan in Columbia County
Direct sow Kai Lan outdoors after April 28 in Columbia County when soil has warmed and frost danger has passed.
Your generous 166.0-day season in Columbia County allows multiple plantings of Kai Lan. Sow every 22.0 days for continuous harvest.
Common pests for Kai Lan in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.
Columbia County receives only 21" of rain annually. Kai Lan needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Direct sow in spring or fall. Harvest when flower buds first appear but before they open. Cut stems at the base to encourage side shoots. Prefers cool weather.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Kai Lan in Other Locations
Frequently Asked Questions
When should I plant Kai Lan in Columbia County, WA?
Columbia County is in Zone 7a with an average last frost of April 28. Plan your Kai Lan planting based on this frost date — see the calendar above for exact timing.
What planting zone is Columbia County, WA?
Columbia County, Washington is in USDA Hardiness Zone 7a. The average last spring frost is April 28 and first fall frost is October 11.
Your Columbia County Garden Planner — Free
A 24-page printable planner built for Columbia 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.