How to Grow Basil from Seed in 10 Simple Steps

Growing basil from seed in early spring is a great way to get a jump on your summer garden. Not only are seeds an inexpensive way to grow loads of the herb, but they also allow you to try out unusual and interesting basil varieties you can’t find at a local garden center. Here’s what you need to know to successfully start basil seeds indoors for planting in your garden when temperatures warm up.

1. Choose the Right Time to Sow Indoors

The optimum time to start growing basil from seed depends on your climate. Basil grows slowly in cool weather, so for an early harvest in cool-weather areas, you can sow seeds indoors in early spring (and then plant outside after the danger of frost is over). It usually takes about six weeks to give your seedlings a good head start on spring, so count backward from your area’s last average frost date to figure out when you should start your seeds indoors.

2. Consider Soaking Seeds for a Boost

Unlike some other seeds, it’s not necessary to soak basil seeds before planting them since they have thin coats. However, some research suggests that soaking basil seeds for a few hours to overnight can jumpstart germination. So think of soaking an option—but not essential for growing success.

3. Fill Pots with Seed-Starting Mix

Start growing basil from seed indoors by filling seed-starting pots or a tray with fresh, moistened seed-starting mix. Don’t use garden soil, which is too heavy and may have insects or diseases in it. Leave about a quarter-inch of room at the top to make watering easier. Choose a container or pot that allows for good drainage. If the pot doesn’t have drainage holes, create them in the bottom.

4. Plant, Water, and Cover Seeds

Plant two to three basil seeds per starter pot by gently pressing them ¼ inch into the soil with your finger. Lightly cover the seeds with soil. Water the seeds sparingly and loosely cover the pot or container with plastic wrap or a dome. This keeps the soil mix and seeds warm to encourage germination.

5. Give Basil Plenty of Light

Basil grown indoors needs lots of light. Put the container in a sunny area, such as near a south-facing window, or place it under a grow light. When the seedlings emerge, remove the plastic wrap or cover. If you use a grow light, adjust the height of the fixture as the plants grow to ensure the bulbs are at least 6 inches above the top of the plants.

6. Increase Air Circulation and Humidity

Place a small fan near the seed starting area to keep the air moving and reduce damping off, a common fungal disease. To boost humidity indoors, place the plants on a tray of wet pebbles to raise the humidity around them. Fill the tray with water until the water’s surface is just below each pot’s bottom. Another option is to place a humidifier nearby.

7. Keep Seedlings Moist

After the indoor basil seedlings start growing, don’t let the soil dry out. It’s essential to keep the basil plants well-hydrated to encourage healthy root growth. These plants do best when provided with about 1 to 2 inches of water per week, but watering will vary depending on your plant’s growing conditions. Watering basil regularly helps your plants become larger and more efficient at absorbing water and nutrients from the soil.

8. Thin Seedlings as Needed

You may notice several seedlings popping up close to one another in your pot or the growing cell of your seed-starting tray. But it’s important to give each seedling healthy room to grow. So when seedlings are about an inch tall, start gently pulling out any that are crowded together (if you’re growing in a seed-starting tray, aim for no more than two seedlings per cell).

9. Repot Seedlings

After basil seedlings reach 2-3 inches tall and have a couple of sets of leaves, transplant individual plants into larger containers with regular potting mix. 

10. Harden Off Basil Seedlings for Transplanting Success

To move your basil plants into outdoor pots or the garden, temperatures need to be consistently above 50°F because basil plants don’t tolerate cold temperatures. Before you transplant seedlings, gradually acclimate them to outdoor conditions by hardening them off: Put them outside for a few hours in a shady spot to let them get used to the differences in temperature, humidity, and air movement. Remember to bring them indoors again at night. Over the next few days, gradually increase the time they spend outdoors.

By the end of the week, the plants should be acclimated and ready to be transplanted outside. In about 60 to 70 days after seeding, you’ll have basil that’s ready for harvesting.