Herbs

Prepared by Karen Russ, HGIC Horticulture Specialist & Al Pertuit, Extension Floriculture Specialist, Clemson University. (New 06/99.)

HGIC 1311

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Most herbs are easy to grow. Many are drought-tolerant, do not need very fertile soil and are naturally resistant to insects and diseases.

The word herb has many definitions, but practically speaking, herbs are plants that are grown for their medicinal, aromatic and/or seasoning uses. Most herbs are herbaceous annuals or perennials. Some, such as lavender and rosemary, are small shrubs.

Landscape Use

Herbs can be used in a number of ways in the ornamental garden. Herbs are often planted in theme gardens such as Biblical gardens, scent gardens, tea gardens, kitchen gardens and apothecary gardens. Many herbs can also be incorporated into the regular flower or mixed border. With delightful scents, attractive shapes and textures, and countless shades of green and gray, herbs can be used to make a garden that appeals to all the senses.

Growing Herbs

Many common herbs are from the Mediterranean region. They are adapted to an area with lots of sun, well-drained, stony soil and dry summers. In South Carolina, they can have difficulty in heavy soils and the ever-present humidity. It is helpful to create raised beds for these plants to improve soil drainage, select cultivars that are tolerant of our climate and use a mulch of stone or gravel to help prevent rots.

Almost all herbs grow best in an area that is sunny for at least six hours each day. The fragrance oils, which account for herb flavors, are produced in the greatest quantity when plants receive plenty of sun. A few herbs-including angelica, parsley and mint-prefer partial shade or shade.

Soil for growing herbs should be well-drained. The soil should have a pH of 6 to 7 and contain a moderate amount of organic matter. Add 2 to 3 inches of fine pine bark, cracked pea gravel, poultry grit or coarse compost worked in to 8 to 12 inches deep to improve the drainage in clay soils. Add 2 to 3 inches of fine pine bark, compost or leaf mold to sandy soils to improve their moisture retention. Build raised beds to further improve drainage. Very few herbs will grow in wet soils, although a few such as mints and lemon-grass thrive in moist soil.

It is best to base fertilizer and lime applications on the results of a soil test. Most herbs do not need a highly fertile soil. Very fertile soils tend to produce lush leaves that lack flavor.

Annual herbs are primarily grown from seeds. Several such as basil, coriander (cilantro) and dill may be directly sown. Seeds of some cold-hardy herbs such as parsley may be sown in the fall. Tender annuals such as basil are sown after all danger of frost is past in the spring.

Most perennial herbs are transplanted from small pots. Plant perennial herbs in the fall if possible so that the plants have time to get well established before summer. Perennials can also be planted in early spring. Pinch out the tips of new plants to force them to branch and become full. Plant aggressively spreading herbs such as the mints in a separate area or confine their roots to a depth of 10 to 12 inches to prevent them from taking over the garden.

Although many herbs are drought-tolerant, moisture is needed to maintain active growth. Water herbs thoroughly and then allow the soil to dry out somewhat before watering again. Plants should be watered early enough in the day that leaves can dry before nightfall. Some herbs, particularly most annual herbs, need additional soil moisture for best growth.

Mulch with organic materials such as compost or composted bark to maintain even soil temperatures, discourage weeds, and retain soil moisture. Herbs with gray leaves, or those that are sensitive to excessive moisture and humidity, can benefit from a 1- to 2-inch mulch of pea gravel or other stones.

Some herbs may be grown in containers and brought inside in winter to provide fresh herbs all year. Bush basil, sage, winter savory, parsley, chives and varieties of oregano and thyme are some of the best herbs for growing in containers. Herbs grown inside will need plenty of sunlight from a south or west window.

Prune herbs regularly to promote vigorous, well shaped, sturdy growth. If you harvest herbs regularly, this should keep your plants pruned.

Problems

The fragrance oils in many herbs repel most insects. However, aphids and spider mites can be a problem. Aphids are common in crowded conditions with rapidly growing, succulent plants. Spider mites thrive in dry conditions and can be discouraged by spraying the plants with a strong stream of plain water regularly during periods of drought. The best defenses against pests on herbs are proper growing conditions, good sanitation, removal of weak or infested growth, and regular pruning.

Harvest & Storage

Herbs should be harvested when the fragrance oils are at their peak. Harvest early in the morning, after the dew dries, but before the heat of the day. Herbs grown for their foliage should be harvested before they flower. Harvest herbs grown for seeds as the seed pods change in color from green to brown to gray but before they shatter. Collect herb flowers just before full flower. Harvest herb roots in the fall after the foliage fades.

Drying is the traditional method of herb preservation. For information on drying herbs, consult the fact sheet HGIC 3086, Drying Herbs, Seeds & Nuts. Freezing is an excellent method to preserve the flavor of certain herbs such as basil that lose flavor when dried. Rinse herbs, then chop coarsely and place in water-filled ice cube trays and freeze.

Species & Cultivars

In addition to the few listed here, possibly hundreds of herbs can be grown successfully in South Carolina. This is a large, diverse and fascinating group of plants.

Basil (Ocimum basilicum): Basil is one of the easiest annual herbs to grow from seed. Plant in the spring after the last frost in full sun and rich, well-drained soil. Harvest leaves frequently to prevent blooming which reduces flavor. Basil is quite tender and will die with the first fall frost. Several species and many cultivars are available. Italian types such as 'Genovese' and 'Lettuce Leaf' have large, sweet, green leaves that are great for pestos. They may grow up to 3 feet tall. Purple basils are mainly used for decorative value, but also make beautiful rose-colored vinegars. Miniature bush basils are used in the same way as the larger basils and are excellent as edgings and in pots. Lemon-scented cultivars are wonderful with fish. Some exotic basils include cinnamon basil, Holy basil (O. sanctum), camphor basil (O. kilimandscharicum), 'African Blue' basil, and Thai basil.

Bay laurel (Laurus nobilis): Bay laurel is a small evergreen tree that produces widely used bay leaves. It is often grown in a container, since it is not reliably hardy while young. Older, established plants can take temperatures down to around 0 °F. Bay laurel thrives in sun to partial shade and a moist soil. The leaves can be used either fresh or dried.

Borage (Borago officinalis): Borage is a self-sowing annual for sunny, dry areas. The young rough leaves and blue star-shaped flowers are used in late spring salads for cucumber flavor. Borage grows to be 2 feet tall. Seed it in the garden in fall or early spring.

Catnip (Nepeta cataria): Catnip is a vigorous perennial with gray-green leaves with a mint-like scent. It grows to 3 feet tall and at least as wide. Cats are attracted to the plant and will roll all over it and even try to scratch it out of the ground. To protect young plants, cage them with chicken wire or grow in hanging baskets. Catnip prefers light shade and well-drained soil.

Chamomile: There are two types of chamomile - English (Chamaemelum nobile) and German (Matricaria recutita). German chamomile is a cool-season annual that grows to about 18 inches tall in sun or part shade. The small white and yellow flowers are produced abundantly and dried for chamomile tea. It is easy to grow from seed sown in early spring and will reseed. Roman chamomile is a low growing perennial ground cover that prefers cool conditions. Plant it in part shade in moderately moist soil. The apple-scented foliage can be used in potpourri. The daisylike flowers can be harvested and brewed as tea.

Chives (Allium schoenoprasum): Chives are easy perennial herbs whose chopped leaves are used in many dishes. The grass-like dark green leaves grow to 12 inches tall. Chives have showy lavender flowers that are edible and used in salads. Chives are the smallest members of the onion family. They are grown from seed or transplants in full sun. Garlic Chives (Allium tuberosum) produce long, flat leaves with a mild garlic flavor. In late summer, they produce showy white blossoms. Garlic chives thrive in full sun. They often reseed prolifically.

Cilantro (Coriandrum sativum): Cilantro is an easily grown annual that is used for both its fresh young greens and for its seeds. Cilantro is used in Latin and Southeast Asian dishes. The onset of summer heat causes it to bolt quickly and go to seed. The seeds are called coriander and are used in Indian cooking and pastries. Grow in full sun to part shade in rich, well-drained soil. Grow cilantro from seed, sowing seeds every few weeks to have a steady supply of young leaves. Vietnamese coriander (Polygonum odoratum) is perennial with a flavor very similar to cilantro. It is used in warm climates where cilantro seeds quickly. Vietnamese coriander grows best in part shade with ample moisture.

Dill (Anethum graveolens): Dill is one of the easiest herbs to grow from seed sown in fall or early spring. It is a cool-weather annual that will go to seed with the onset of hot weather. Feathery young leaves are used in salads and with vegetables and fish. The ripe seeds and unripe seed heads are used in pickling. The large green caterpillars that love to eat dill are swallowtail butterfly larvae. Do not plant dill near fennel since they can cross and produce strangely flavored seedlings. Dill readily self seeds.

Fennel (Foeniculum officinalis): Fennel is a perennial or biennial herb that looks much like dill, but is anise-scented and grows up to 4 feet tall when flowering. Young leaves are used commonly with fish and the seeds are used for flavoring teas and sausages. Fennel attracts swallowtail butterfly caterpillars. Several bronze-leafed cultivars are highly ornamental and have the same flavor. All types can self-seed to the point of invasiveness.

Lavender (Lavandula species): A number of different species are grown, but the English lavender is the best-known and least-adapted to growing in Southern heat. Several other species and cultivars will thrive in South Carolina if they are given their main cultural needs - excellent soil drainage and full sun. Some of the best for growing in a hot climate include: the Lavadin group (Lavandula x intermedia) including a number of cultivars such as 'Dutch,' 'Provence,' and 'Grosso,' Spanish lavender (Lavandula stoechas); French lavender (Lavandula dentata); and sweet lavender (Lavandula heterophylla). Most are bushy with narrow grayish evergreen leaves. The flowers are wonderfully fragrant in bluish purple spikes. Lavender is used in potpourri and sachets, and can also be used for tea and flavoring desserts.

Lavender cotton (Santolina species): Lavender cotton is a small shrubby evergreen perennial that is often used as edging because it can be sheared into a compact hedge. There are deep green and gray foliaged species. The yellow flowers can be sheared off to maintain a tidy look. The finely cut leaves are fragrant and can be used in potpourris. The plants do best in hot, dry, sunny locations.

Lemon balm (Mellisa officinalis): Lemon balm is an easy-to-grow perennial. It has a strong, sweet lemon scent and makes a delightful tea. The heart-shaped leaves are light green, or yellow in some cultivars. Lemon balm grows to 1½ feet high in sun or partial shade, with well-drained soil. It will spread and self-sow readily.

Lemongrass (Cymbopogon citratus): Lemongrass is a lemon-flavored relative of pampas grass that grows to 4 feet tall. The swollen, white, lower end of the stem is the part used. Lemongrass makes a great tea, and is widely used in southeastern Asian cooking. It grows in full sun to part shade. It is hardy near the coast.

Lemon verbena (Aloysia triphylla): Lemon verbena is the most sweetly scented of all lemony herbs. This rather sprawling shrub is tender and will need to be overwintered inside except near the coast. It can be cut back and all leaves removed before storing inside in a cool area until spring, so does not need much room. Lemon verbena is excellent used in teas, cold drinks, sweets and potpourris. It prefers moist soil and full sun.

Marjoram (Origanum majorana): Marjoram is similar to oregano, but milder in flavor. It is easy to grow as an annual. Plants grow 6 to 9 inches tall with small, gray-green leaves and pale mauve flowers. Grow in full sun with moderate watering. Start seed indoors and set transplant out after the last killing frost.

Mexican tarragon or mint marigold (Tagetes lucida): Mexican tarragon is grown as a heat-and drought-tolerant substitute for true tarragon, which is very difficult to grow in the South. This perennial has an excellent anise aroma and can be used in any dish that calls for tarragon. Grow in full sun.

Mints (Mentha species): Mints are a very large group of herbs with many species and cultivars in a wide range of flavors. Most have several traits in common. They are easy, vigorous growers that can become invasive if not confined. All prefer to grow in rich, moist or even damp soil in part shade. It is best to grow mints from cuttings, roots or transplants. Mint seed does not come true to type. Harvest leaves frequently to encourage best growth and prevent flowering. Spearmint (Mentha spicata) is one of the easiest to grow. This is the traditional mint for use in mint juleps and mint tea. Peppermint (Mentha x piperita) has the flavor of candy canes. Other mints include ginger mint (Mentha x gentilis), applemint (Mentha rotundifolia), pineapple mint ( Mentha suaveolens 'Variegata') and the very dwarf Corsican mint (Mentha corsica).

Oregano (Origanum vulgare): Oregano is used to season meats, stews, soups, spaghetti sauce and pizza. Unlike most herbs, the leaves are best used dried. Oregano is a hardy perennial and does well in containers. It grows to 2 feet tall, with small rounded leaves and pale pink flowers. Plant oregano in full sun and well-drained soil. Greek oregano (Origanum heracleoticum) is highly prized for its sharp, biting oregano taste.

Parsley (Petroselinum crispum): Parsley is commonly used as a garnish. The attractively curled leaves are tasty and loaded with vitamins. Two forms are commonly available - the flat leaved or Italian parsley, and the curled or French parsley. They can be grown from seeds sown in early spring or transplants. Seed is slow to germinate. Parsley is a biennial, producing leaves the first year and flowers the next. Grow parsley in light shade with rich, moist soil.

Rosemary (Rosemarinus officinalis): Rosemary is a beautiful evergreen shrub that comes in many forms from bushes four feet tall or more to low-growing groundcovers. The fragrance is strong and distinctive, used in many meat dishes, especially chicken. Rosemary typically has gray-green or dark green needlelike leaves and blue or occasionally white flowers. There are many different cultivars that vary in size, shape and even flavor. Weeping and pine-scented cultivars are available. All grow best in dry, sunny areas. Rosemary varies in its hardiness; in the Upstate one of the reliably hardy varieties such as 'Arp' or 'Hill Hardy' should be selected.

Sage (Salvia officinalis): Sage is a small evergreen shrub with broad oval, gray-green leaves that are used to flavor soups, stews and poultry stuffing. Fresh sage has an especially nice flavor. The plants require excellent drainage and dry soil in full sun. Sage can be difficult to grow in coastal areas. Some cultivars include sages with purple or gold leaves. The cultivar 'Bergarten' seems to be better adapted to heat than the species. Pineapple sage (Salvia elegans) grows to 4 feet tall with lush green leaves and brilliant red flowers in late summer. The flowers attract butterflies and hummingbirds. The leaves have an intense pineapple scent. Pineapple sage is usually hardy, but may succumb to a hard winter in the Upstate.

Scented geraniums (Pelargonium species): These tender perennials are often grown in containers so that they can be brought in easily for winter. They are not grown for their insignificant flowers, but for their deliciously scented leaves. Many species and cultivars are available, with scents including rose, apple, apricot, cinnamon, lemon, peppermint, spice, and others. They are used in cookies, cakes, teas and in potpourris. They require sun and good soil.

Southernwood (Artemisia abrotanum): Southernwood is an extremely fragrant shrubby perennial with ferny gray green leaves. The plants grow 3 to 4 feet tall. The aromatic leaves are scented of camphor, lemon or tangerine, depending on variety. It is used in potpourris and as a moth repellent. Southernwood grows best in full sun in well drained, dry soil. Other names for this plant include lad's love and old man.

Sweet Annie (Artemesia annua): Sweet Annie is an easily grown annual that grows rapidly to 5 to 6 feet tall. The sweetly fragrant, soft lacy leaves and flower heads are used extensively in dried arrangements and wreaths. Grow in full sun with moderate water. Sweet Annie reseeds abundantly, so locate it where this will not be a problem.

Thyme (Thymus species): Thyme is widely used to flavor many different foods. There are numerous species available, with a range of flavors and forms. Some types are mainly ornamental used for attractive growth habit and flowers. The plants are generally low growing, from virtually flat to the ground to a little over a foot tall. Many are evergreen, or have silvery, wooly leaves. In general, the taller growing species and those with smooth leaves will tolerate heat and humidity better than low growing or wooly types. Plant thyme in full sun in very well drained soil that stays dry

Winter savory (Satureja montana): Winter savory is a shrub-like perennial that grows to be about 1 foot tall. The leaves are gathered before flowering to season beans and meats. Clip often to encourage flavorful new growth. Summer savory (Satureja hortensis) is an annual used to season meats and vegetables. It does not grow as well in the south as winter savory. Georgia savory (Satureja georgiana) is a native savory with small, dark, glossy, scented leaves and pink flowers in late summer. It is both highly ornamental and an excellent heat tolerant substitute for summer and winter savories.

Wormwood (Artemisia absinthium): Wormwood is a perennial with very aromatic, lacy silver foliage. It is used ornamentally and as a moth repellent. Give excellent drainage and full sun.

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