When to Plant Yarrow in St. Tammany Parish, LA
May to-do list for St. Tammany Parish, Louisiana
Your St. Tammany Parish, Louisiana garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.
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Start harvesting yarrow
The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.
A few tasks this May that'll pay off in June
- First harvests: yarrow
Yarrow is a drought-tolerant perennial herb with feathery foliage and flat-topped flower clusters in white, yellow, pink, or red. It attracts beneficial insects and is used in herbal medicine.
St. Tammany Parish, Louisiana is in USDA Zone 9a. The average last spring frost is February 20 and the first fall frost is November 23, giving you a growing season of approximately 276 days.
At an elevation of 321 feet, St. Tammany Parish receives approximately 57.9 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 96°F, so Yarrow may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Yarrow will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Yarrow root diseases.
St. Tammany Parish Soil Profile
Soil Type
Sandy Loam
Soil pH
4.8-6.1
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 St. Tammany Parish
How your county's soil matches Yarrow's growing requirements.
Soil pH
Your soil pH (4.8–6.1) is more acidic than Yarrow prefers (5.5–7.0). Add garden lime to raise pH.
Soil Texture
Sandy soil in St. Tammany Parish warms quickly in spring but drains fast. Yarrow will need more frequent watering and regular compost additions to retain nutrients.
Drainage
Yarrow prefers dry conditions but your soil drains poorly. Use raised beds or mounded rows to prevent root rot.
Organic Matter
Organic matter is moderate (2.1%). Annual compost additions will help Yarrow.
How to Plant Yarrow
Plant Water Budget
Monthly Watering Guide for Yarrow
Yarrow needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.
| Month | Yarrow Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 4.5" | 0" | ❄️ Dormant |
| Feb | 2.2" | 4.5" | 0" | ✅ Rainfall sufficient |
| Mar | 2.2" | 5.8" | 0" | ✅ Rainfall sufficient |
| Apr | 2.2" | 4.2" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 5.2" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 4.6" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 6.8" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 5.3" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 4.2" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 4.1" | 0" | ✅ Rainfall sufficient |
| Nov | 2.2" | 4.3" | 0" | ✅ Rainfall sufficient |
| Dec | — | 4.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Feb–Nov in St. Tammany Parish). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Yarrow 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.
Yarrow Planting Timeline — St. Tammany Parish, LA
Yarrow Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | February 27 | Feb 27 – Mar 13 |
| Harvest | May 29 | May 29 – Aug 14 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Transplant Outdoors |
| March | Transplant Outdoors |
| April | — |
| May | Harvest |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
90–120 days
🧪 Soil pH
Needs 5.5–7 · Your soil: too_acidic
🗺️ USDA Zone
Zone 9a
📆 Growing Season
276 days in St. Tammany Parish
Growing Tips for Yarrow in St. Tammany Parish
Direct sow Yarrow outdoors after February 20 in St. Tammany Parish when soil has warmed and frost danger has passed.
Sandy soil in St. Tammany Parish dries quickly — mulch Yarrow with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.
With summer highs reaching 96°F in St. Tammany Parish, provide afternoon shade for Yarrow and water deeply in the morning.
Common pests for Yarrow in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.
General growing tips
Direct sow or start from divisions. Yarrow thrives in poor soil and is very drought-tolerant. Deadhead to encourage reblooming. Divide clumps every 3 years.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Yarrow in Other Locations
Frequently Asked Questions
When should I plant Yarrow in St. Tammany Parish, LA?
St. Tammany Parish is in Zone 9a with an average last frost of February 20. Plan your Yarrow planting based on this frost date — see the calendar above for exact timing.
What planting zone is St. Tammany Parish, LA?
St. Tammany Parish, Louisiana is in USDA Hardiness Zone 9a. The average last spring frost is February 20 and first fall frost is November 23.
Your St. Tammany Parish Garden Planner — Free
A 24-page printable planner built for St. Tammany Parish (Zone 9a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.