When to Plant Watercress in San Jacinto County, TX
Top priorities for San Jacinto County, Texas gardeners in May
Welcome to May in Zone 9a. These are the moves that will have the biggest impact on your growing season.
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Collect watercress at their peak
This is the payoff month. Bring a basket, bring a friend, and get into the beds.
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.
San Jacinto County, Texas is in USDA Zone 9a. The average last spring frost is February 18 and the first fall frost is December 1, giving you a growing season of approximately 286 days.
At an elevation of 6 feet, San Jacinto County receives approximately 71.3 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 94°F, providing good warmth for Watercress during the growing season. Sandy soil warms quickly in spring — great for early planting — but Watercress will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Watercress root diseases.
San Jacinto County Soil Profile
Soil Type
Sandy Loam
Soil pH
5.3-6.7
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 San Jacinto County
How your county's soil matches Watercress's growing requirements.
Soil pH
Your soil pH (5.3–6.7) is more acidic than Watercress prefers (6.5–7.5). Add garden lime to raise pH.
Soil Texture
Sandy soil in San Jacinto County warms quickly in spring but drains fast. Watercress will need more frequent watering and regular compost additions to retain nutrients.
Organic Matter
Organic matter is moderate (2.2%). Annual compost additions will help Watercress.
How to Plant Watercress
Fall planting: Sow 8 weeks before your first frost date for a fall harvest.
Succession Planting Watercress
Sow every 4.6 weeks. Last sowing by Oct 02 to harvest before frost.
For a dedicated fall crop, sow by Oct 06.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
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 | — | 1.7" | 0" | ❄️ Dormant |
| Feb | 6.5" | 2.5" | 4" | 🚿 Regular watering |
| Mar | 6.5" | 4.2" | 2.3" | 💧 Light watering |
| Apr | 6.5" | 8.5" | 0" | ✅ Rainfall sufficient |
| May | 6.5" | 9.5" | 0" | ✅ Rainfall sufficient |
| Jun | 6.5" | 11.4" | 0" | ✅ Rainfall sufficient |
| Jul | 6.5" | 9.2" | 0" | ✅ Rainfall sufficient |
| Aug | 6.5" | 8" | 0" | ✅ Rainfall sufficient |
| Sep | 6.5" | 6.7" | 0" | ✅ Rainfall sufficient |
| Oct | 6.5" | 5.2" | 1.3" | 💧 Light watering |
| Nov | 6.5" | 2.6" | 3.9" | 🚿 Regular watering |
| Dec | 6.5" | 1.9" | 4.6" | 🚿 Regular watering |
Water needs are for active growing months only (Feb–Dec in San Jacinto 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 — San Jacinto County, TX
Watercress Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 21 | Jan 21 – Feb 4 |
| Transplant Outdoors | February 18 | Feb 18 – Mar 4 |
| Direct Sow | January 28 | Jan 28 – Feb 18 |
| Harvest | April 1 | Apr 1 – May 6 |
| Fall Sowing | October 6 | Oct 6 – Oct 20 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors Direct Sow |
| February | Start Indoors Transplant Outdoors Direct Sow |
| March | Transplant Outdoors |
| April | Harvest |
| May | Harvest |
| June | — |
| July | — |
| August | — |
| September | — |
| October | Fall Sowing |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
1.5"/week · 1-2 times/week
📅 Days to Maturity
40–60 days
🧪 Soil pH
Needs 6.5–7.5 · Your soil: too_acidic
🗺️ USDA Zone
Zone 9a
📆 Growing Season
286 days in San Jacinto County
Growing Tips for Watercress in San Jacinto County
Direct sow Watercress outdoors after February 18 in San Jacinto County when soil has warmed and frost danger has passed.
Sandy soil in San Jacinto County dries quickly — mulch Watercress with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.
Your generous 287.0-day season in San Jacinto 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 San Jacinto County, TX?
San Jacinto County is in Zone 9a with an average last frost of February 18. Plan your Watercress planting based on this frost date — see the calendar above for exact timing.
What planting zone is San Jacinto County, TX?
San Jacinto County, Texas is in USDA Hardiness Zone 9a. The average last spring frost is February 18 and first fall frost is December 1.
Your San Jacinto County Garden Planner — Free
A 24-page printable planner built for San Jacinto County (Zone 9a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.