When to Plant Basil
Published: April 21, 2026
The classic companion to tomatoes in both the garden and the kitchen. Basil is a heat-loving herb that thrives in summer but is killed by even a brief cold snap below 50°F.
When to plant basil
- Start seeds indoors: 6 weeks before last frost
- Direct sow outdoors: 2 weeks after last frost
- Minimum soil temperature: 60°F
- Days to harvest: 30–60 days
- Sun requirement: Full sun (6+ hours)
- Spacing: 12 inches apart
- Water: 1 inches per week
- Fall crop: No — single spring/summer crop only
Growing Tips for Basil
- •Never expose basil to temperatures below 50°F — even briefly — it turns black and dies.
- •Pinch flower buds immediately as they appear to keep leaves large and productive.
- •Harvest by cutting whole stems from the top, leaving lower sets of leaves to branch out.
- •Plant next to tomatoes — basil is proven to repel whiteflies, aphids, and spider mites from tomato plants.
Companion Planting for Basil
✅ Plant basil with
- • Tomato
- • Pepper
- • Marigold
- • Oregano
❌ Avoid planting near
- • Sage
- • Fennel
- • Thyme
- • Rosemary
Common Basil Pests and Problems
Regional pest pressure varies — see your state guide below for state-specific pest calendars and treatment timing.
Basil Planting Dates by State
Select your state for exact sow and transplant dates based on local frost calendars.
Frequently Asked Questions
When do I plant basil outside?
Transplant basil outdoors 2 weeks after your last frost date, once nighttime temperatures stay consistently above 50°F. Basil is extremely frost-sensitive — a single night below 40°F can blacken leaves. When in doubt, wait an extra week.
Should I start basil indoors?
Starting indoors 6 weeks before last frost gives you earlier, larger plants. Use seed trays with heat mats (basil germinates best at 70–75°F). Direct sowing outdoors after last frost also works well — basil seedlings establish quickly in warm soil.
How do I keep basil from flowering?
Pinch off flower buds as soon as you see them forming. Once basil flowers (bolts), leaves become smaller and more bitter. Pinching redirects the plant's energy back into leaf production and keeps plants bushy and productive for months longer.
Why does my basil turn black?
Basil blackens from cold damage (below 50°F), overwatering, or fusarium wilt disease. Keep basil away from cold drafts, water at soil level rather than on leaves, and ensure good drainage. Outdoors, bring potted basil inside before nighttime temperatures drop below 55°F in fall.
What grows well with basil?
Tomatoes and basil are the classic garden partnership — basil is proven to repel whiteflies, spider mites, and aphids from tomato plants, while tomatoes provide light shelter for basil in the hottest afternoon hours. Marigolds round out the trio for a pest-resistant vegetable bed.