Best Plants to Start Indoors in March
March is the perfect time to start seeds indoors. You'll have strong seedlings ready to transplant after the last frost, giving you a head start on the growing season. Here are the 15 best plants to start indoors in March.
Why Start Seeds Indoors in March?
Most plants need 6-8 weeks from seed to transplant-ready seedling. Starting in March means:
- Ready for May transplant: Perfect timing for spring planting after last frost
- Longer growing season: Harvest earlier and produce more
- Cost savings: Seeds are 10x cheaper than buying seedlings
- More variety: Nurseries stock common varieties; seeds give you hundreds of options
Best Vegetables to Start in March
1. Tomatoes
Days to germination: 5-10 days
Transplant: 6-8 weeks (early May)
Why now: Tomatoes need a long growing season. Starting in March gives you ripe tomatoes by July.
2. Peppers (Bell & Hot)
Days to germination: 7-14 days
Transplant: 8-10 weeks (mid-May)
Why now: Peppers germinate slowly and need warm soil. Indoor start is essential for most climates.
3. Eggplant
Days to germination: 7-14 days
Transplant: 8-10 weeks
Why now: Heat-loving plant needs a long season. Indoor start extends growing time.
4. Broccoli
Days to germination: 5-10 days
Transplant: 4-6 weeks (mid-April)
Why now: Cool-season crop. Plant early for spring harvest before summer heat.
5. Cabbage
Days to germination: 5-10 days
Transplant: 4-6 weeks
Why now: Like broccoli, cabbage thrives in cool spring weather.
6. Cauliflower
Days to germination: 5-10 days
Transplant: 4-6 weeks
Why now: Tricky to grow; indoor start gives you control over temperature.
Best Herbs to Start in March
7. Basil
Days to germination: 5-10 days
Transplant: 6 weeks (or keep indoors year-round)
Why now: Frost-sensitive. Indoor start protects seedlings until warm weather arrives.
8. Parsley
Days to germination: 14-21 days
Transplant: 8 weeks
Why now: Slow germinator. Starting in March gives it time to establish.
9. Cilantro
Days to germination: 7-10 days
Transplant: 4 weeks (or direct sow outside)
Why now: Bolts quickly in heat. Early spring planting extends harvest.
Best Flowers to Start in March
10. Marigolds
Days to germination: 5-7 days
Transplant: 6 weeks
Why now: Companion plant for vegetables. Deters pests naturally.
11. Zinnias
Days to germination: 5-7 days
Transplant: 4-6 weeks
Why now: Fast-growing annual. Perfect for cutting gardens.
12. Cosmos
Days to germination: 7-10 days
Transplant: 4-6 weeks
Why now: Low-maintenance flower. Attracts pollinators.
13. Sunflowers
Days to germination: 7-10 days
Transplant: 2-3 weeks (or direct sow)
Why now: Can direct sow, but indoor start protects from birds and pests.
Easy-to-Grow Options for Beginners
14. Lettuce
Days to germination: 2-7 days
Transplant: 3-4 weeks
Why now: Fastest crop. You'll have salad greens by late April.
15. Kale
Days to germination: 5-7 days
Transplant: 4-6 weeks
Why now: Hardy, nutritious, and nearly impossible to kill.
Indoor Seed Starting Tips
- Use seed starting mix: Not garden soil. Sterile, lightweight mix prevents disease.
- Bottom heat helps: Seedling heat mat speeds germination by 30-50%.
- Light matters: Seedlings need 12-16 hours of light. Use grow lights or south-facing window.
- Don't overwater: Moist, not soggy. Overwatering kills more seedlings than drought.
- Harden off before transplanting: Gradually expose seedlings to outdoor conditions over 7-10 days.
What NOT to Start Indoors
Some plants transplant poorly or grow too fast:
- Carrots, radishes, beets: Hate transplanting. Direct sow outside.
- Beans, peas: Germinate so fast there's no advantage to indoor start.
- Squash, cucumbers, melons: Can start indoors 2-3 weeks before last frost, but March is too early.
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