Best Plants to Start Indoors in March

March 3, 2026 · 7 min read

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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