When to Plant Snapdragon in Sullivan County, TN
Top priorities for Sullivan County, Tennessee gardeners in June
June rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Sullivan County, Tennessee.
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Start harvesting snapdragon
Morning harvests are best — cooler temperatures mean crisper produce and longer fridge life.
Get ahead of July
- Starting indoors: snapdragon
- First harvests: snapdragon
Snapdragons (Antirrhinum majus) are classic cool-season annuals whose upright spikes of dragon-lipped flowers are among spring's most dramatic displays. Tolerating light frosts, they bloom from early spring until summer heat shuts them down — then often revive in fall. In zones 9-11 they are grown as fall-planted winter annuals and may re-seed to naturalize.
Sullivan County, Tennessee is in USDA Zone 7b. The average last spring frost is April 23 and the first fall frost is October 19, giving you a growing season of approximately 179 days.
At an elevation of 3,986 feet, Sullivan County receives approximately 46.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Snapdragon during the growing season.
Sullivan County Soil Profile
Soil Type
Silt Loam
Soil pH
5.4-7.1
Drainage
Well Drained
Snapdragon 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 Sullivan County
How your county's soil matches Snapdragon's growing requirements.
Soil pH
Your soil pH (5.4–7.1) overlaps with Snapdragon's range (6.2–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Sullivan County is excellent for Snapdragon — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.5%). Annual compost additions will help Snapdragon.
How to Plant Snapdragon
Fall planting: Sow 8 weeks before your first frost date for a fall harvest.
Succession Planting Snapdragon
Sow every 8 weeks. Last sowing by Jul 11 to harvest before frost.
For a dedicated fall crop, sow by Aug 24.
Snapdragon Water Budget
Monthly Watering Guide for Snapdragon
Snapdragon needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Snapdragon Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 3.9" | 0" | ❄️ Dormant |
| Feb | — | 3.3" | 0" | ❄️ Dormant |
| Mar | — | 4.7" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3.3" | 1" | 💧 Light watering |
| May | 4.3" | 3.6" | 0.7" | 💧 Light watering |
| Jun | 4.3" | 4.1" | 0.2" | 💧 Light watering |
| Jul | 4.3" | 4.8" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 4.9" | 0" | ✅ Rainfall sufficient |
| Sep | 4.3" | 3.3" | 1" | 💧 Light watering |
| Oct | 4.3" | 3.2" | 1.1" | 💧 Light watering |
| Nov | — | 3.8" | 0" | ❄️ Dormant |
| Dec | — | 3.7" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Sullivan County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Snapdragon 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.
Snapdragon Planting Timeline — Sullivan County, TN
Snapdragon Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 12 | Feb 12 – Feb 26 |
| Transplant Outdoors | April 16 | Apr 16 – Apr 30 |
| Direct Sow | March 26 | Mar 26 – Apr 16 |
| Bloom | June 25 | Jun 25 – Oct 1 |
| Fall Sowing | August 24 | Aug 24 – Sep 7 |
· 9" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Direct Sow |
| April | Transplant Outdoors Direct Sow |
| May | — |
| June | Bloom |
| July | Bloom |
| August | Fall Sowing Bloom |
| September | Fall Sowing Bloom |
| October | Bloom |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Natural rainfall sufficient
📅 Days to Maturity
70–100 days
🧪 Soil pH
Needs 6.2–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 7b
📆 Growing Season
179 days in Sullivan County
Growing Tips for Snapdragon in Sullivan County
Direct sow Snapdragon outdoors after April 23 in Sullivan County when soil has warmed and frost danger has passed.
General growing tips
Start indoors 10-12 weeks before last frost; seeds need light to germinate — press into moist medium and do not cover. Transplant after hardening off, even if light frosts remain. Pinch seedlings once to encourage branching. Deadhead to prolong blooming. In zones 8-11, sow in fall for a winter-to-spring show. Tall varieties (24-36") make excellent cut flowers.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Snapdragon in Other Locations
Frequently Asked Questions
When should I plant Snapdragon in Sullivan County, TN?
Sullivan County is in Zone 7b with an average last frost of April 23. Plan your Snapdragon planting based on this frost date — see the calendar above for exact timing.
What planting zone is Sullivan County, TN?
Sullivan County, Tennessee is in USDA Hardiness Zone 7b. The average last spring frost is April 23 and first fall frost is October 19.
Your Sullivan County Garden Planner — Free
A 22-page printable planner built for Sullivan County (Zone 7b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.