📍 Houston, TX · Zone 9b · Last frost Tuesday, February 10, 2026
✏️ ChangeWhen to Plant Marigold in Houston, Texas (77021)
Location
Houston, Texas
ZIP Code
77021
USDA Zone
9b
Last Frost
Tuesday, February 10, 2026
📅 Your 2026 Planting Dates
Start Seeds Indoors
Tuesday, December 30, 2025
Transplant Outdoors
Tuesday, February 24, 2026
Based on last frost Tuesday, February 10, 2026 · Zone 9b
Pro tip: Start Marigold seeds indoors 6 weeks before your last frost date, then transplant outdoors around Tuesday, February 24, 2026.
🌿 Plant Details
☀️ Growing Requirements
☀️
Sun
Full Sun (6-8 hours)
💧
Water
Moderate (1 inch/week)
↔️
Spacing
12" apart
🌱
Planting Depth
0.25" deep
Seeds typically germinate in 5-10 days
Ready to Plant Marigold in Houston?
Get your seeds now so they're ready by Tuesday, December 30, 2025.
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🤝 Good Companions
Full Companion Planting Guide for Marigold
See which plants help Marigold thrive, which to keep away, and raised bed layout tips →
🛠️ Supplies You'll Need
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Common Marigold Varieties
Popular cultivars to look for at your local nursery or seed supplier.
French Marigold (Dainty Marietta)
Small, prolific marigold with bicolor yellow-red blooms on compact 10-inch plants.
African Crackerjack
Tall African marigold with huge 3–4 inch pompom flowers in gold, orange, and yellow.
Signet (Gem Series)
Edible, citrus-scented single blooms on lacy foliage; excellent in salads and as a garnish.
Vanilla
Unique creamy-white African marigold; novel color that stands out in any garden bed.
Safari Mix
Compact French marigold mix with early blooms; excellent container and edging plant.
Common Marigold Problems
What to watch for — and how to fix it before it spreads.
Pests
Common in hot, dry conditions; cause bronzed, stippled leaves and fine webbing.
Increase humidity; spray with insecticidal soap or neem oil; avoid dusty conditions.
Chew ragged holes in young transplants and seedlings overnight.
Apply diatomaceous earth; use beer traps; water in the morning to keep soil dry at night.
Diseases
Gray fuzzy mold on flowers and stems in cool, wet conditions; petals turn brown and mushy.
Remove spent blooms promptly; improve airflow; avoid wetting flowers when irrigating.
White powdery coating on leaves; worse in humid weather with poor airflow.
Space plants adequately; apply potassium bicarbonate; choose resistant varieties.
Phytoplasma spread by leafhoppers causes distorted, yellowed growth and malformed flowers.
Remove and destroy infected plants; control leafhopper populations with row covers.
Common Mistakes
Spent blooms left on the plant signal it to stop flowering and focus on seed production.
Remove dead flowers weekly to extend the blooming season into fall frost.
Marigolds transplant poorly if root-bound; young transplants actually do better.
Start 4–6 weeks before last frost (not earlier); or direct-sow after frost — they grow fast.
🌾 Seed Saving Guide
🟢 EasyWhen to Harvest Seed
Allow flower heads to dry completely on the plant until the petals are papery and brown.
Processing
Pull seeds (needle-like slivers at base of petals) from dried heads, dry 1 week before storing.
Seed Viability
Up to 2 years when stored cool, dark, and dry.
Pro Tip
French marigolds (T. patula) are often OP. African marigolds (T. erecta) can be hybrid — check variety before saving.
Raised Bed Planting Guides
A 4×8 bed fits 32 plants of Marigold. See plant counts, spacing grids, and companion pairings for every bed size →
Frequently Asked Questions
When should I plant Marigold in Houston, Texas? +
In Houston (Zone 9b), start Marigold seeds indoors around Tuesday, December 30, 2025 and transplant outdoors around Tuesday, February 24, 2026.
What is the last frost date for Houston, Texas? +
The average last spring frost date for Houston, Texas (ZIP 77021) is around Tuesday, February 10, 2026. This is based on NOAA climate normals for USDA Zone 9b.
How long does Marigold take to grow? +
Marigold typically matures in about 50 days from transplanting. In Houston, that means you can expect harvest around Tuesday, February 24, 2026 plus 50 days.
Should I start Marigold indoors or direct sow in Texas? +
Marigold should be started indoors 6 weeks before your last frost date. In Houston, that means starting around Tuesday, December 30, 2025.
📚 More Marigold Planting Guides
Other Plants for Houston
Growing Marigold in Zone 9b
Marigold (Tagetes patula) is a popular garden vegetable. In Houston, Texas, which is in USDA Hardiness Zone 9b, you should start seeds indoors around Tuesday, December 30, 2025.
Your average last frost date is Tuesday, February 10, 2026. Plan to transplant your Marigold seedlings outdoors around Tuesday, February 24, 2026, about 2 weeks after your last frost date.