University of Vermont
Department of Plant and Soil Science

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THE MANY USES AND TYPES OF BASIL

Dr. Leonard Perry, Horticulture Professor Emeritus
University of Vermont
 
Basil is a well-known culinary herb that's popular in many Italian dishes. But did you know that there are many other uses of this herb, including its use as a tonic to aid in digestion? In addition to uses other than cooking, basil comes in various varieties and flavors.

The most common use of basil is for cooking, such as in tomato sauce, pesto, or vinegars. But it also can be sprinkled over salads and sliced tomatoes, either whole or chopped. Actually, don’t chop the leaves, but tear them instead for the most flavor. One of my favorite salads is the simple Italian Caprese salad, consisting of slices of tomato and mozzarella, topped with basil leaves and a vinaigrette or Italian dressing.

To make oil for salads, pound the fresh leaves and mix with a good salad or vegetable oil. If freezing the leaves, coat them with olive oil first. Leaves also can be dried and stored in salt.

In the landscape, don’t merely relegate basil to the herb or vegetable garden. Consider planting it in scented gardens, or use it as edging along a bed or path that you'll brush past and release the aroma. Or try mass plantings of basil in a border, plant in decorative outdoor containers, or grow in pots indoors if you have lots of light. In ancient times, pots of basil on the windowsill were used to deter flies.

Other uses of basil include the cosmetic. Put fresh leaves in a hot bath as an infusion, for example. As a tonic, steep a few leaves in wine for several hours. Or steep in water as a tea to aid digestion. A drop of basil oil on shirtsleeves will help counteract mental fatigue.

Basil can be propagated from seed. Sow seeds eight to ten weeks before planting outside in a well-drained soil. Or sow directly in the garden. Your site should have rich, well-drained soil with plenty of sunlight for several hours a day.

Throughout the season, remove flower spikes to promote increased growth and branching. Pruning the plants every two to three weeks also will promote growth. Basil is grown as an annual, as it does not tolerate frost well.  If you want to overwinter plants, take stem cuttings late in the season to root, or dig whole plants in early fall and pot to overwinter indoors.

Basil has few if any insect pests, chewed leaves possibly indicating Japanese beetles, and holes with slimy trails indicating slugs (mostly seen during wet weather).  Sudden leaf wilting and perhaps plant death, plus vertical brown streaks on stems, indicates the fusarium fungus disease.  Rotating crops yearly to a different area, and buying seeds certified free of this disease, are means to avoid its spread. 

A relatively new disease on basil is downy mildew.  Watch for yellowing leaves, similar to a nutrient deficiency only with black fuzz growth too on leaf undersides.  Means to avoid this are starting your own plants from certified clean seeds, minimizing leaf wetness such as from overhead watering, and plenty of air circulation through wide spacing of plants.  If you see or suspect this disease, look for fungicides labeled for its control, such as organic ones containing neem oil or potassium bicarbonate. While sweet basil is susceptible to downy mildew, many other varieties are quite resistant.

Bush Basil (Ocimum basilicum)--also known as Sweet, Common or Genovese Basil--is the most widely grown basil, and is native to the Old World Tropics (India, Africa, Asia). In India it is believed to hold divine essence. In some Greek Orthodox churches it is used to prepare holy water, as it was found growing around Christ's tomb after the Resurrection. In Haiti, bush basil is associated with a pagan love goddess named Erzulie, and in Mexico it is used in potions to attract lovers.  There are many variants and cultivars (cultivated varieties) of sweet basil.

‘Cinnamon’ basil, also known as Mexican basil, is a common basil whose leaves have the same chemical as found in the cinnamon spice.  A botanic variety of sweet basil, the Thai basil (thyrsiflora), is sometimes called anise or licorice basil from the slightly spicy flavor of its leaves.  The small, narrow leaves hold up better than regular sweet basil in high temperature cooking, so is widely used for this in Southeast Asia.  ‘Siam Queen’ is a popular cultivar you may see of Thai basil.

'Green Globe' is a compact mound, only about a foot high, and great for edging. The foliage is green to purple, again depending on cultivar, and is distinctly aromatic. ‘Spicy Globe’ is similar, with very small leaves having a very strong flavor.

'Purple Ruffles' and Dark Opal (or ‘Purpurascens’) are popular cultivars with both purple foliage and ruffled edges to the leaves. The flowers are terminal, spike-like racemes that are usually purple or white. Dark Opal was bred at the University of Connecticut in the 1950’s. ‘Pesto Perpetuo’ is upright, growing 12 to 18-inches high, with thin white margins on the leaves and no flowers.  Both this and the purple cultivars make attractive ornamental annuals foliage plants for the garden. 

There are a couple types of American basil (O. americanum) you may find for different flavors—lemon and lime basils.  The Thai lemon basil comes from another hybrid species (O. x citriodorum).  Another lemon basil (O. x africanum) has a bushy habit, grows to two feet tall, and has an intense lemony fragrance.  It is a hybrid between the American and the bush basil, and is used in Asian cooking in stews, curries, stir-fries, and rice dishes.

Among the less common basils are the Camphor Basil (O. kilimandscharicum)-- a tender annual shrub reaching about five feet tall in a season. It becomes woody with camphor-scented leaves that can be used in sachets to protect woolens and as a tea for medicinal uses such as stomach aches.

Clove, sometimes known as Tree or African Basil (O. gratissimum), is similar to Camphor Basil and has fuzzy, lime-green leaves scented like pennyroyal. A tea of its leaves is used for colds and fevers, the leaves are burned to repel mosquitoes, and the thymol content of one cultivar makes this useful for wounds, gargling, and conjunctivitis.

Holy Basil (O. tenuiflorum or sanctum) is an annual shrub with spicy clove-like scented leaves that reaches two feet in height. It is the sacred basil of the Hindus, who use it in both cooking and medicines. According to Hindu mythology, this native of tropical Asia (also known as “Tulsi”) symbolizes the goddess Lakshmi—the wife of Vishnu, one of the most sacred deities in this religion.

With all these types of basil, you may want to try several in an herb garden or even mixed in with flowers.  If using basil for cooking, a couple plants should suffice for a couple or even for a family.  If making pesto, you may want a dozen or so plants of sweet basil.  Whether in ground beds or in pots, keep a few plants near the kitchen so they’re handy when needed.

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