Basil: King of the Herb Garden
Everything You Need to Know to Grow and Use Basil
by Wendy Priesnitz

Can you imagine a garden without basil? Impossible! Its familiar fragrance, easy care, and many uses make it indispensable in herb, ornamental, and container gardens – and, of course, in the kitchen.

A Sense of History

Basil has been known and grown since ancient times. According to Gerard in his Herbal published in England in the 1600s, the smell of basil was “good for the heart and for the head.” The seeds “cureth the infirmities of the heart and taketh away the sorrow which commeth with melancholy and maketh a man merry and glad.” Gerard also advised that the juice of the plant was good against headaches, if it were drunk with wine, and was useful in clearing up diseases of the eye.

Back in the first century AD, however, the Greek physician Dioscorides believed basil dulled the sight and produced “wind.” Others claimed it bred scorpions and that scorpions would be found beneath a pot where basil grew – a belief that arose, perhaps, from the prevalence of scorpions in some of the tropical regions of Asia and Africa, where basil originated, and their predilection for warm, dark places. Gerard wrote that those who were stung by a scorpion would feel no pain if they had eaten basil. Culpepper, a contemporary of Gerard, suggested in his Herbal that basil would draw out the poison of venomous beasts, wasps or hornets. Today, herbalists claim it helps to ease flatulence and abdominal pains if taken as an infusion.

Basil made its way to Europe by the Middle Ages and to England and America in the mid-17th century, where it was used mainly medicinally. It was not until the 19th century that basil became the ever-present component of herb gardens that it is today.

The range of basils available is the result of the variability of the species, basilicum. The species contains a natural diversity of fragrances and colors; plant breeders have selected for and improved on these different traits.

What’s In A Name?

A member of the mint family (Labiatae), as so many herbs are, 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. The genus name of sweet basil, Ocimum, is from a Greek verb that means “to be fragrant.” The species name, basilicum, comes from the Greek basileus, which means “king or prince.” Basil is often referred to as the “king of herbs,” and no wonder – it is one of the most useful, and most used, of all herbs.

In frost-free climates, sweet basil (O. basilicum) may act as a perennial, but in most areas of the country, it is an annual, dying at the first touch of frost. There are more than 30 different species of basil, but the most commonly grown are O. basilicum and its subspecies.

Holy basil, O. sanctum (also known as O. tenuiflorum), is a sacred herb in India, where it is used in religious ceremonies and planted around Hindu temples; with its pinkish purple flowers, it is most often planted as an ornamental.

The four basic types of garden basils are the familiar sweet green basil, dwarf green basil, purple-leaved basil and scented leaf basil. Sweet basil grows about two feet tall. It has rather large leaves, two to three 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, a 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 to 12 inches high. The leaves are small, about a half- 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, Purple Ruffle and Red Rubin 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. 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 55 to 60 degrees. When sown or transplanted at the right time, basil is one of the easiest herbs to grow successfully.

Starting Basil Indoors

Plan to sow seeds four to six weeks before the date of your average last frost in spring. Basils do not need a long time to grow large enough to transplant to the garden.

Fill a shallow container, or flat, or individual two-inch pots with a commercial seed-starting 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.

Set the containers in a warm location; the growing medium should be at about 70 to 75 degrees F (21 to 23 degrees C).

Seedlings will emerge in four to seven 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 containers in a sink filled with a couple of inches of water until beads of moisture appear on the surface. Compost tea or a liquid fertilizer at one half the recommended rate can be given to seedlings to promote healthy plants.

When the seedlings are about two 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 one with a scissors. It is not necessary to transplant purple-leaved basils if you sow them about one inch apart.

If young plants become tall and spindly, pinch the tip to encourage compact growth. Some of the smaller basils have a naturally branching habit and do not need to be pinched.

Sowing Directly in the Garden

Sow seeds in the garden when the soil has warmed up to about 55 to 60F (13 to 15C) degrees day and night temperatures. Sow the seeds about one-half 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 two to three 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 three to four inches tall.

To have an uninterrupted supply of fresh basil, most gardeners sow basil seed several times during the growing season. The National Garden Bureau recommends sowing basil seed every three to four weeks to harvest fresh leaves for culinary uses.

Selecting Bedding Plants

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.

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.

Next, you must prepare the soil. Although herbs are not particularly fussy, they do need a light, fertile soil with good drainage. Amend what you have by digging in about a two-inch layer of peat moss and compost before planting. This is particularly important if your soil is mostly clay.

Transplant. Choose a cloudy, calm day or late afternoon to transplant your basils 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. Put 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. If they don’t come out easily and you need to handle the plants, do so by their leaves, not their stems (plants replace leaves more readily than stems). If you started plants in peat pots, set the pots below the soil line – they have a tendency to dry out quickly when exposed to the air.

Space plants ten to twelve inches apart; dwarf basils, eight to 10 inches apart; larger basils should be up to 20 inches apart. Water the plants immediately after setting them in the ground.

Garden Uses

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-leaf 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, sedum, fountain grass, dusty miller, and blue salvia. 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 basils around a patio or in containers on a deck.

Taking Care of Basil

Like most herbs, basils do not require much maintenance. In sandy or infertile soil, fertilize basil plants for continuous growth. If you amended the soil with organic matter, you may not need to fertilize basil. Basil plants need about an inch (2.5 cm)of water a week. Water them regularly, if rain does not provide for the plants’ needs.

Although the flower spikes are attractive, it is recommended to cut them off as they deplete the plants’ energy resulting in fewer leaves.

The leaves have the best flavor – the most essential oils – when they are harvested before the plants flower. Cut whole stems rather than individual leaves, especially if you want to use the leaves as a garnish because they bruise easily. Cutting whole stems is a tasty way of creating a bushy, compact plant: Cut just above a pair of lower leaves; the plant will produce new shoots at that point.

Growing in Containers

Basils are excellent herbs to grow in containers because they add such attractive colors and textures to the plantings. They look good in pots or window boxes in full sun. A container of basil by the back door or on a deck provides easy access for harvesting!

The container should have drainage holes in the bottom or sides. Fill it with a soilless mix, which is more lightweight than garden soil and is also free of diseases and weed seeds. It is easy to provide nutrients all season by incorporating a controlled-release fertilizer in the mix before planting.

With mixed plantings, place most basils near the center of containers or at the ends of window boxes. Use dwarf basils to edge a container planting or on their own in smaller, eight-inch pots, and place the pots around a larger planter, marching up steps, or along a walk.

Plant basils at the same level as, or just slightly deeper than, they were growing in their original pots. Water the container well after planting. Keep them evenly moist through the growing season; the roots of any plants in a container cannot reach down or out in search of available moisture.

Windowsill Plants

It is easy to bring container-grown plants inside, but you can also pot up a few plants from the garden. Cut them back rather severely – to about three to four inches tall – so they will put out new growth when they become acclimated to the indoor environment.

Grow them on the sunniest windowsill you have, preferably with a southern exposure. Keep the soil evenly moist and fertilize them once a month.

Because basils are so easy to grow from seed, it is just as simple to sow fresh seed indoors at the end of the outdoor growing season. Pot the seedlings into individual four-inch to six-inch containers and enjoy fresh basil all winter harvested from your windowsill.

Pests and Diseases

You may find a few aphids or Japanese beetles that like your basil as much as you do. To circumvent aphids, wash them off the plants with a strong spray of water from the garden hose. Pick or knock Japanese beetles off into a jar of soapy water and discard.

Fusarium wilt is a soil-borne fungus that causes yellowing of foliage, discoloration of the stems, reduced height and eventual wilting of the entire plant. If you plant basil in the same garden place year after year this could be a problem. The best cure is prevention. Because it can overwinter in the soil, don’t plant basil in the same location every year. Avoid excessive watering and provide proper drainage in order to reduce the spread of Fusarium wilt.

This article was written with the assistance of the National Garden Bureau.