How to Grow Basil from Seed: Complete Indoor & Outdoor Guide
Fresh basil costs $3 for a tiny package at the store. One packet of basil seeds gives you dozens of plants for the same price — and they'll produce all season long. Here's how to grow basil from seed indoors and out, plus the best varieties for beginners.
Niwa Gardening Guide
Herbs · 7 min read
Why grow basil from seed?
Basil plants at the nursery cost $2–4 each and give you one variety — usually Genovese. A packet of basil seeds costs the same but contains 50–100 seeds, letting you grow dozens of plants and try multiple varieties like Thai basil, lemon basil, or purple ruffles basil.
Basil is also one of the easiest herbs to grow from seed. Seeds germinate in 5–10 days, and you can start harvesting in 60–75 days. Unlike finicky vegetables, basil seeds are forgiving and grow quickly enough to give you multiple sowings per season.
Perfect companion plant: Basil and tomatoes are the classic garden pairing. Basil may help repel pests that attack tomatoes, and they ripen at the same time for perfect caprese salads. Learn more about effective plant pairings in our companion planting guide.
When to start basil seeds
Basil is a warm-season herb that's sensitive to cold. Start seeds indoors 4–6 weeks before your last frost date, or direct sow outdoors 2 weeks after all danger of frost has passed.
| Growing Method | Best Timing | Pros | Cons |
|---|---|---|---|
| Indoor seed starting | 4–6 weeks before last frost | Earlier harvest, controlled environment, higher success rate | Requires grow lights or sunny window |
| Direct sowing outdoors | 2+ weeks after last frost | No transplant shock, less work | Later harvest, weather dependent |
| Succession sowing | Every 2–3 weeks through summer | Continuous fresh basil | Requires planning and multiple sowings |
For continuous harvest, start new basil seeds every 2–3 weeks from your first indoor sowing through midsummer. This gives you fresh, tender leaves all season long rather than a few large, woody plants.
How to start basil seeds indoors
Choose your containers and soil
Use seed starting trays, small pots, or any container with drainage holes. Fill with seed starting mix — never garden soil, which is too heavy for containers. Seed starting mix is lightweight, sterile, and drains well.
Sow the seeds
Plant basil seeds ¼ inch deep, 2–3 seeds per cell or small pot. Basil seeds are tiny, so sowing multiple seeds ensures good germination. You'll thin to the strongest seedling later.
Provide warmth and moisture
Keep soil temperature between 70–80°F (21–27°C) for best germination. Use a heat mat if necessary. Mist lightly to keep soil moist but not waterlogged. Cover with plastic wrap or a humidity dome until seeds sprout.
Add light once germinated
Remove plastic covering once seeds sprout (5–10 days). Place under grow lights 2–4 inches above seedlings, or in a south-facing window with 6+ hours of direct sun. Run lights 14–16 hours per day.
Thin and fertilize
Once seedlings have 2–3 sets of true leaves, thin to one plant per container by cutting extras at soil level. Start fertilizing weekly with diluted liquid fertilizer (half strength).
Transplanting basil outdoors
Basil seedlings are ready to transplant when they're 3–4 inches tall and have several sets of true leaves, usually 4–6 weeks after sowing. Most importantly, wait until nighttime temperatures stay above 50°F (10°C) — a single cold night can damage or kill basil plants.
Hardening off
Harden off seedlings for 7–10 days before transplanting. Start by placing them outside in a sheltered, shaded spot for 1–2 hours, gradually increasing outdoor time and sun exposure each day. This prevents transplant shock from sudden changes in light, wind, and temperature.
Planting location
Choose a spot with full sun (6–8 hours daily) and well-draining soil. Basil prefers slightly alkaline soil (pH 6.0–7.5) but adapts to most garden soils as long as drainage is good. In heavy clay soils, plant in raised beds or add compost to improve drainage.
Space plants 8–12 inches apart. Basil grows 12–24 inches tall and wide, depending on variety, and good air circulation prevents fungal diseases.
Direct sowing basil outdoors
You can sow basil seeds directly in the garden once soil temperatures reach 60°F (15°C) and nighttime lows stay above 50°F (10°C). Direct sowing works best in warm climates or for succession plantings in summer.
Prepare the soil by loosening to 6–8 inches deep and mixing in compost. Sow seeds ¼ inch deep and 2–3 inches apart. Thin seedlings to 8–12 inches apart once they're 2–3 inches tall. Keep soil consistently moist until germination (7–14 days outdoors).
Best basil varieties for beginners
| Variety | Type | Days to Harvest | Best Uses |
|---|---|---|---|
| Genovese | Sweet basil | 60–75 days | Classic pesto, Italian dishes, tomato pairing |
| Sweet Basil | Sweet basil | 65–75 days | All-purpose cooking, very easy to grow |
| Thai Basil | Asian variety | 60–70 days | Stir-fries, curry, Southeast Asian cuisine |
| Lemon Basil | Citrus variety | 60–65 days | Fish, chicken, tea, fruit salads |
| Purple Ruffles | Ornamental | 70–80 days | Garnish, vinegars, beautiful purple leaves |
| Spicy Globe | Compact variety | 60–70 days | Containers, small spaces, borders |
Beginner recommendation: Start with Genovese or Sweet Basil. They're the most forgiving, produce heavily, and work in most recipes. Once you're comfortable growing basil, experiment with specialty varieties like Thai or lemon basil.
Caring for basil plants
Watering
Water deeply when the top inch of soil feels dry, usually 1–2 times per week. Water at the base of plants to keep leaves dry and prevent fungal diseases. Basil needs consistent moisture but good drainage — soggy soil causes root rot.
Fertilizing
Basil is a light feeder. Mix compost into the soil at planting, then side-dress with compost or apply liquid fertilizer every 3–4 weeks during the growing season. Avoid high-nitrogen fertilizers, which promote leaf growth at the expense of flavor.
Pinching flowers
Pinch off flower buds as soon as they appear to keep plants producing tender leaves. Once basil flowers, leaves become bitter and production slows. Regular harvesting and flower pinching keep plants productive all season.
Harvesting basil
Start harvesting when plants are 4–6 inches tall, about 60–75 days from seed. Cut stems just above a pair of leaves — new growth will emerge from that point. Harvest regularly to encourage bushy growth and prevent flowering.
For the best flavor, harvest in the morning after dew has dried but before the heat of the day. Use fresh immediately, or store cut stems in water like flowers. Fresh basil lasts 7–10 days this way.
Preserving basil
Freeze basil in ice cube trays with olive oil, make pesto and freeze in portions, or dry leaves in a food dehydrator. Basil doesn't air-dry well — the leaves turn black and lose flavor. For year-round basil, plan on preserving your harvest rather than drying.
Common basil growing problems
Seeds won't germinate
Most often caused by soil that's too cool (below 65°F) or too wet. Basil seeds need warmth and moisture, but not waterlogged conditions. Use a heat mat and ensure good drainage.
Seedlings are leggy
Insufficient light. Basil seedlings need 14–16 hours of bright light daily. Move closer to grow lights or supplement window light with artificial lighting.
Leaves turning yellow or black
Usually overwatering or cold damage. Check soil drainage and ensure nighttime temperatures stay above 50°F. Water only when the top inch of soil is dry.
Plants stop producing
Probably flowering. Pinch off all flower buds and harvest regularly to keep plants in vegetative growth. Once basil sets seed, leaf production slows dramatically.
Frequently Asked Questions
Can I grow basil indoors year-round?
Yes, but it requires bright light (grow lights) and good air circulation. Indoor basil won't grow as large as outdoor plants, but you can have fresh basil through winter with proper lighting.
How long does basil take to grow from seed?
Basil seeds germinate in 5–10 days indoors, 7–14 days outdoors. You can start harvesting small amounts at 4–6 weeks, with full production beginning around 60–75 days from seed.
Why are my basil seeds not sprouting?
The most common causes are soil too cold (below 65°F), soil too wet or too dry, or old seeds. Basil seeds remain viable for 5 years when stored properly, but germination rates decline after 2–3 years.
Can I save seeds from my basil plants?
Yes, but only from open-pollinated varieties (not hybrids). Let flowers mature and dry on the plant, then collect the small black seeds. Store in a cool, dry place for next year's planting.
What's the best basil for pesto?
Genovese basil is traditional for pesto and has the classic sweet, slightly spicy flavor that pairs perfectly with pine nuts and parmesan. Sweet basil works well too and is easier to find as seeds.
Plan your basil harvest: Niwa helps you time your basil planting perfectly for continuous harvests all season. The app calculates your ideal sowing dates based on your location and tracks when each planting will be ready to harvest. Download free →
Growing basil from seed is easier than you think
Basil is one of the most rewarding herbs to grow from seed — fast, forgiving, and productive. Start with Genovese or Sweet Basil for your first attempt, and you'll be harvesting fresh basil within two months. Once you see how easy and economical it is, you'll never buy overpriced basil plants again.
The key is starting with good quality seeds, providing adequate warmth for germination, and keeping plants consistently watered but well-drained. With proper timing and care, one packet of basil seeds will keep your kitchen stocked with fresh herbs all growing season.
