How to Grow and Care for Basil Plants—Indoors and Outside

All basil (Ocimum basilicum) needs is sun, water, and a bit of pruning in order to grow long, luscious, and aromatic leaves. This low-maintenance herb is an excellent companion plant in the garden, as its fragrant smell can help deter pests. But basil can also grow well on a kitchen windowsill for easy harvesting. Basil comes in several varieties, from sweet to spicy, and it can be found in shades like dark green and deep purple. While basil is known for being easy to care for, there are some things it needs in order to thrive, whether you're growing it indoors or outside.

How to Plant Basil From Seed

For basil to grow well, it needs six hours of sun a day, so take a good look at your yard to see where it's sunniest. Since the herb thrives in warm temperatures, plant it outside after your last spring frost. If you don't have a yard, plant basil in a container and put it near a window where it has access to a lot of sunlight.

1. Sow seeds evenly, covering with a 1/4-inch of soil.
2. Keep the soil moist until the seeds germinate, which takes about five to seven days.
3. Once the seedlings emerge, thin them to be 3 to 4 inches apart.
4. Continue to thin seedlings so they stand 6 to 12 inches apart once they have developed two to three sets of true leaves.

Starting Seeds Indoors

If you're growing basil from seed indoors, start them six to eight weeks before your last frost, says Melinda Myers, gardening expert, author, and host of the Great Courses' "How to Grow Anything" DVD series. You can follow the same process as above, but sow the seeds in small containers or starter trays and transplant them to larger containers once the seedlings develop two to three sets of true leaves.

Types of Basil

If you're looking for a diverse plant to grow, put basil on your radar. "There are 60 different species of basil, all of which thrive in sunny, hot conditions and are frost sensitive," says Brie Arthur, a horticulturist and author of The Foodscape Revolution and Gardening with Grains. These are some of the most common basil varieties to grow:

Thai Basil

Thai basil (O. basilicum var. thyrsiflora) is typically found in Southeast Asia and Vietnam, says Sabine H. Schoenberg, the host of Sabine's New House on Smart Healthy Green Living. "It has a licorice, anise-like fragrance and is commonly used in stir-fry dishes in Asia," she says. "The leaves are slightly serrated and have purple stems."

Genovese Basil

If you love to cook with basil, then you've likely come across this popular variety: Genovese basil (Ocimum basilicum 'Genovese'). "The large, flavorful leaves are ideal for eating both fresh and dried and provide the traditional essence of Italian cuisine," says Arthur. "This species is native to central Africa and is used worldwide." The slightly curled leaves produce a sweet and slightly spicy flavor.

Lemon Basil

Lemon basil (Ocimum africanum) has elongated oval-shaped leaves and a sweet, tangy flavor. "One of its biggest advantages is being undesirable to browsing animals such as deer and rabbits," says Arthur. "Lemon basil adds a punch of taste when used fresh in dishes and can also be added to flavor water and tea."

Cinnamon Basil

As the name implies, cinnamon basil (Ocimum basilicum 'Cinnamon') has a cinnamon-like, spicy fragrance. "It is found in teas and baked goods for its cinnamon flavor," says Schoenberg. "This variety stands out from the pack thanks to its leaves, which are narrow with reddish-purple veins."

Holy Basil

Holy basil (Ocimum sanctum) is known for its sweet anise flavor. There are four types of this basil: Rami, Krishna, Amrita, and Vana, says Arthur. These attract pollinators and also have green-and-purple foliage and shiny leaves.

How to Care for Basil

While basil is relatively low-maintenance, there are some things to keep in mind when caring for this herb.

Soil

Basil likes rich, organic soils whether you're planting in the ground, a raised bed, or a container, says Myers. To improve your in-ground garden soil, amend it by adding compost. As for potting mix—which you fill containers with—use an organic combination that includes some compost, as well as peat moss and rice hulls for drainage, Myers says.

Watering

Make sure to water your basil plants regularly, since they can suffer in dry conditions. "The leaves will flag or droop, indicating they need a drink," says Arthur. Potted plants will need more water than growing directly in the ground.

Fertilizing

Apply a slow-release organic fertilizer when planting your basil, and then add a liquid feed of kelp meal once a month. "That will provide all the macro and micronutrients the basil needs to thrive," Arthur says.

How to Prune Basil

When tiny flowers begin to grow on your basil plants, or your plants reach more than 6 inches in height, it's time to start pruning. "Prune or harvest frequently to keep the blooms at bay and prevent the stems from becoming woody. Once stems become woody, the basil becomes bitter and past its prime," says Mark Whittier, color and foliage merchant at Pike Nurseries. When pruned often, basil can yield an ongoing supply of leaves.

How to Propagate Basil

One of the easiest ways to propagate basil is by placing it in water, says Schoenberg.

1. Take a 3- to 4-inch cutting of your basil stem, snipping below the leaf nodes.
2. Remove all of the leaves except the top two sets.
3. Fill a clean glass with water and place the cutting in the water.
4. Keep the glass in a sunny spot and wait for roots to develop.
5. Once the roots are at least 1 inch in length, the cutting is ready to transplant into soil.

How to Repot Basil

If you're growing basil in a container, repotting it ensures it doesn't become root-bound. Once the plant begins to outgrow its current container, repot it in midsummer to extend its life through the growing season, says Arthur.

1. Remove the plant from its existing pot and move it into a larger container or into the ground.
2. To eliminate transplant shock, keep the same soil so the roots will start growing easily again.
3. Backfill in with extra soil as needed.
4. Do a hard prune by cutting the branches back to a lower leaf, which will stimulate new growth and generate the freshest basil clippings possible.
5. Water well so the soil is moist.

How to Harvest Basil

Harvest basil as needed. "Cut just above a node—where the main stem meets two side stems—for the most attractive leaves to use on salads, sandwiches, and pizzas," says Whittier. "Pick off the lower leaves for drying and cooking."

How to Store Basil

After picking the leaves from your plant, save any extra to be used at a later date. To store fresh-cut basil, tie a few stems together and pace it in a water-filled glass with a produce bag wrapped around the top.

Common Problems With Basil

Basil performs best in warm conditions with evenly moist soil. Even with optimal conditions, some issues may arise. Here are the most common problems you may come cross as you grow basil—and how to remedy them.

Pests

Aphids, slugs, and snails are pests that commonly feed on basil. To keep them at bay, lightly spray natural insecticidal soap on the leaves of your plant, says Arthur. Avoid using chemicals to remedy pest infestations, as they could affect the flavor of the plants.

Fungus

Basil plants sometimes suffer from fungal infections. This usually occurs through contaminated seeds or infected transplants. When you spot the disease, cut off effected leaves and stems.

Yellowing

Yellowing leaves are the result of overwatering and typically appear at the bottom of the plant. If you see a yellow leaf, simply cut it off and scale back your watering schedule. "As a general guideline, water basil when the top 1 to 2 inches of soil is dry," says Schoenberg.