How to Grow Basil From Seed

Basil is a warm-season herb that hates the cold, so timing comes down to warmth, not the calendar. Start seeds indoors about 6 weeks before your last spring frost, then wait to set plants outside until nights stay reliably above 50F and the soil has truly warmed. You can also direct-sow basil straight into the garden once frost is well past and the ground is warm. In warm zones, keep sowing a fresh batch every few weeks for a steady supply of tender leaves all summer.

Basil is one of the easiest herbs to start from seed. Sow the small seeds about a quarter inch deep in rich, well-drained soil or moist seed-starting mix, and press them in gently so they stay in contact with the soil. Keep the mix evenly moist and warm, around 70F, and seedlings usually appear in 5 to 10 days. Give them plenty of bright light so they grow stout rather than leggy, and once plants have a few sets of true leaves, thin or space them 8 to 12 inches apart in full sun.

Basil rewards a little attention with a lot of leaves. Water regularly to keep the soil evenly moist but never waterlogged, watering at the base in the morning so the foliage dries quickly. Give it full sun and a light feed, and pinch out the tips once plants reach 6 inches so they branch and stay bushy. Pinch off flower buds the moment you see them, which keeps the plant making tender leaves instead of setting seed. Climate matters most at the ends of the season here: basil is very cold-sensitive, so gardeners in the Northeast and Midwest should wait until nights stay above 50 degrees and the soil hits 60 before setting plants out, while growers in the Deep South, Texas, and Southern California get a long, productive run and mainly need to water well and give afternoon shade through the hottest weeks to slow bolting.

Basil is a famously good garden neighbor, especially for tomatoes, and its strong scent helps confuse and deter many common pests. These four make especially good companions, and you can add any of them in one click:

Start picking once plants are 6 to 8 inches tall and bushy. Always harvest by pinching or snipping just above a pair of leaves, taking the top few inches of a stem rather than stripping individual leaves. This tells the plant to branch out and doubles your future harvest. Cut in the morning when the oils are strongest, harvest regularly to keep it productive, and never take more than about a third of the plant at once.

Use Genovese basil fresh and add it at the very end of cooking, since heat turns the leaves dark and dulls the flavor within minutes. Tear it over pizza and pasta off the heat, layer it with mozzarella and ripe tomatoes for Caprese, and blend big handfuls into pesto with pine nuts, garlic, and olive oil. Stir it into soups and sauces just before serving, and tuck a few leaves into salads and sandwiches. A single row keeps the kitchen in fresh basil all summer.

• Bolting (flowering): heat and stress make basil send up flower spikes and turn bitter. Pinch off flower buds as soon as they appear and harvest often to keep leaves coming.
• Cold damage: basil blackens in a chill. Keep it warm, and never set plants out until nights stay above 50F.
• Damping off: seedlings collapse at the soil line in cool, damp, still air. Sow in fresh mix, give good airflow and bright light, and avoid overwatering.
• Yellowing leaves: usually overwatering or poor drainage. Let the top inch of soil dry between waterings and grow in well-drained soil.
• Leggy seedlings: too little light. Grow in full sun or under bright grow lights and pinch the tips to encourage bushy growth.