When to Plant Watercress in Johnston County, OK
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.
Johnston County, Oklahoma is in USDA Zone 7b. The average last spring frost is March 25 and the first fall frost is November 11, giving you a growing season of approximately 231 days.
At an elevation of 700 feet, Johnston County receives approximately 32.9 inches of rainfall annually with predominantly loam soil. Summer highs average 92°F, providing good warmth for Watercress during the growing season.
Johnston County Soil Profile
Soil Type
Loam
Soil pH
6.3-7.3
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 Johnston County
How your county's soil matches Watercress's growing requirements.
Soil pH
Your soil pH (6.3–7.3) overlaps with Watercress's range (6.5–7.5), though not a perfect match.
Soil Texture
The loam soil in Johnston County is excellent for Watercress — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.2%) — 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 Sep 12 to harvest before frost.
For a dedicated fall crop, sow by Sep 02.
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 | — | 0.8" | 0" | ❄️ Dormant |
| Feb | — | 1" | 0" | ❄️ Dormant |
| Mar | 6.5" | 2.3" | 4.2" | 🚿 Regular watering |
| Apr | 6.5" | 3.4" | 3.1" | 💧 Light watering |
| May | 6.5" | 5.1" | 1.4" | 💧 Light watering |
| Jun | 6.5" | 5.2" | 1.3" | 💧 Light watering |
| Jul | 6.5" | 3.8" | 2.7" | 💧 Light watering |
| Aug | 6.5" | 3.7" | 2.8" | 💧 Light watering |
| Sep | 6.5" | 3.7" | 2.8" | 💧 Light watering |
| Oct | 6.5" | 2.1" | 4.4" | 🚿 Regular watering |
| Nov | 6.5" | 1" | 5.5" | 🚿 Regular watering |
| Dec | — | 0.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Johnston County). 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 — Johnston County, OK
Watercress Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 18 | Feb 18 – Mar 4 |
| Transplant Outdoors | March 25 | Mar 25 – Apr 8 |
| Direct Sow | March 11 | Mar 11 – Apr 1 |
| Harvest | May 6 | May 6 – Jun 10 |
| Fall Sowing | September 2 | Sep 2 – Sep 16 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors Transplant Outdoors Direct Sow |
| April | Transplant Outdoors Direct Sow |
| May | Harvest |
| June | Harvest |
| July | — |
| August | — |
| September | Fall Sowing |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
1.5"/week · 2-3 times/week
📅 Days to Maturity
40–60 days
🧪 Soil pH
Needs 6.5–7.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 7b
📆 Growing Season
231 days in Johnston County
Growing Tips for Watercress in Johnston County
Direct sow Watercress outdoors after March 25 in Johnston County when soil has warmed and frost danger has passed.
Your generous 231.0-day season in Johnston County 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 Johnston County, OK?
Johnston County is in Zone 7b with an average last frost of March 25. Plan your Watercress planting based on this frost date — see the calendar above for exact timing.
What planting zone is Johnston County, OK?
Johnston County, Oklahoma is in USDA Hardiness Zone 7b. The average last spring frost is March 25 and first fall frost is November 11.
Plan Your Garden with Confidence
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