How to Grow Basil
Basil is a member of the mint family (Labiatae). Basils have the familiar four-sided stems and whorled flowers of that family; they are not, however, in the least invasive, as mints can be. There are four basic types of garden basils grown: sweet green basil, dwarf green basil, purple-leaved basil, and scented leaf basil.
Sweet basil (O. basilicum) grows about 2 feet tall. It has rather large leaves, 2-3 inches long, and produces white flower spikes. It is the most widely grown. Its “cousins” include lettuce-leaf and Genovese basils—varieties with much larger leaves—as well as the spicy Thai basil, ‘Siam Queen’ (1997 All-America Selections winner), an improved tropical basil with an intense fragrance and flavor.
Dwarf basil (O. b. ‘Minimum’) is also known as bush or fine green basil. Its compact growth reaches 10-12 inches high. The leaves are small, about 1/2 inch long, and flowers are white. ‘Spicy Globe’ and ‘Green Bouquet’ are well-known dwarf types; the former is aptly named because the plants grow naturally into rounded, globe shapes.
Purple-leaved basils (O. b. purpurescens) are very ornamental. ‘Dark Opal’ (1962 All-America Selections winner), ‘Purple Ruffles’ (1987 AAS winner) and ‘Red Rubin’ (with solid purple leaves, an improved strain of ‘Dark Opal’) are three of the most popular varieties. These basils tend to have ruffled, frilled, or deeply cut leaves, which are very pungent; they produce deep pink to lavender-purple flowers
Scented-leaf basils bring additional aromas to the basic clove-anise of sweet basil. Lemon basil (O. americanum, O.basilicum var. citriodorum) has a very distinct lemon flavor, especially in the newest ‘Sweet Dani’ (1998 AAS winner). The leaves are grayish green, the flowers white. The leaves of cinnamon basil have a spicy cinnamon flavor; flowers are deep pink with purple bracts. Anise basil has a flavor similar to licorice; its flowers are slightly purplish.
Growing From Seed
Whether you sow seeds indoors or out, remember that basil does not like cold, or even cool, weather. Sow the seeds outdoors when day and night temperatures reach about 12-15 degrees Celsius. When sown or transplanted at the right time, basil is one of the easiest herbs to grow successfully. Basil traditionally hits maturity in 80-90 days.
Light: Full Sun
Seed Depth: ¼” or 6mm
Seed Spacing: 1” or 2.5cm
Row Spacing: 18” or 45cm
Days to germinate: 7-10
Starting Basil Indoors
Starting basil indoors is a great way to get a heads start on planting which will provide you with even more basil to cook with. Plan to sow seeds 4 to 6 weeks before the date of your average last frost in spring. Basil does not need a long time to grow large enough to transplant to the garden.
- Fill a shallow container, flat, or individual 2- to 2 1/4-inch pots with a commercial seed-starting mix (such as Pro-Mix) Moisten the mix and let it drain. Sow the seeds in rows in a flat or two to three seeds per pot. Cover the seeds with about 1/4 inch of the mix. Press the mix down lightly and spritz the surface with water to moisten it and settle the seeds.
- To keep the mix from drying out while the seeds are germinating, cover the containers with sheets of clear plastic wrap, or place each in a plastic bag and close it with a twist-tie (preferably a proper seeding tray and clear dome will give you the best results).
- Set the containers in a warm location; the growing medium should be at about 21-23 degrees Celsius. Seedlings will emerge in 4 to 7 days. When they do, remove the plastic covering and place the containers in bright light or direct sun in a south-facing window or a fluorescent light garden. Give the containers a quarter turn every few days so the plants grow straight instead of leaning towards the light source.
- Keep the mix evenly moist by watering from the bottom: Set the container in a sink filled with a couple of inches of water until beads of moisture appear on the surface. A liquid fertilizer at one half the recommended rate can be given to seedlings to promote healthy plants.
- When the seedlings are about 2 inches tall and have at least two pairs of true leaves, transplant those in flats to individual pots. Thin those started in small pots to one per pot by snipping off all but the strongest looking plant with a scissors. It is not necessary to transplant purple-leaved basils, such as ‘Dark Opal’ and ‘Purple Ruffles’, if you sow them about 1/2-1 inch apart. If young plants become tall and spindly, the growing tip can be pinched to encourage branching and compact growth.
Sowing Directly in the Garden
Sow seeds in the garden when the soil has warmed up to about 15 degrees Celsius. Sow the seeds about 1/2 inch deep in good garden soil; if you cover the seeds with less soil, they may float to the surface after a heavy rain. Basil germinates readily, therefore you do not need to sow thickly. You can sow the seeds in rows or in groups; drop two to three seeds in each hole for the latter. Keep the seedbed moist until germination occurs. When the seedlings have at least two pairs of true leaves and are 2 to 3 inches tall, thin them to stand 10 to 30 inches apart, depending on the species or cultivar. Begin pinching out the growing tips for compact growth when the seedlings are 3 to 4 inches tall. To have an uninterrupted supply of fresh basil, most gardeners sow basil seed several times during the growing season.
Basil from Transplants
Basil is so popular that you can readily purchase plants at garden centers or nurseries in addition to growing it from seed. The plants may be sold in individual pots, six-packs or flats. Look for young, compact plants. Avoid tall, leggy plants—even though you can correct their growth habit somewhat by cutting them back after you have planted them at home. The leaves of sweet basil should be a clear deep green; spots on the leaves may indicate they have been exposed to the cold. Pass up plants that have obvious pests, such as aphids, on stems or leaves. If you can’t plant the herbs the day you bring them home, set them in a protected area away from the drying effects of direct sun and wind until you can put them in the ground or in containers.
Out In The Garden
Select a Site. Basil grows best in a location that receives full sun—at least six hours (or more) of direct sun daily. With less sun, the plants have a tendency to get “leggy.” Plants in containers require the same exposure. Prepare the Soil. Although herbs are not very fussy, they do need a light, fertile soil with good drainage. Amend what you have by digging in about a 2-inch layer of peat moss and compost before planting. This is particularly important if your soil is mostly clay.
Choose a cloudy, calm day or late afternoon to transplant basil to give them a chance to settle in before they have to contend with the drying effects of sun and wind. It is very important to plant at the right time, which means not too early in the season. The slightest cold will set them back. Set the plants in the ground at the same depth they were growing in the pots. If you bought six-packs or flats of basil plants, water them first; then carefully lift each plant out of its cell or separate them from each other in the flat, keeping as much soil around the roots as possible to minimize moisture loss. Space plants 10-12 inches apart; dwarf basils, 8-10 inches apart; larger basils, such as ‘Sweet Dani’, up to 20 inches apart. Water the plants immediately after setting them in the ground.
To help grow the best basil try growing with these companion plants - Tomatoes, Peppers, Oregano and asparagus. Petunias are also helpful in repelling thrips, flies and mosquitoes. Sage is known to be an incompatible plant with basil.
Basil is as ornamental as it is edible. Put it in a traditional herb garden, in the vegetable plot in the center of a bed of red and green-leaf lettuces or edging a bed of tomatoes. Use both the green- and purple-leaved varieties in borders; the latter are especially beautiful with perennials such as coral bells (Heuchera ‘Palace Purple’), Sedum ‘Vera Jameson’, fountain grass (Pennisetum), dusty miller, and blue Salvia farinacea. Both combine well with annuals, such as dwarf or medium-height snapdragons, nicotiana, French marigolds, and petunias. With its natural round shape, the dwarf basil ‘Spicy Globe’ makes a wonderful edging for any type of garden: perennial, rose, or herb. Try the old-fashioned technique of keeping flies away by planting basil around a patio or in containers on a deck.