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University
of Rhode Island GreenShare Factsheets
Growing,
Harvesting, & Using Culinary Herbs
Herbs
are various kinds of herbaceous plants whose fresh or dried parts
are used to season foods, provide fragrances, supply natural
dyes or make industrial and pharmaceutical products. Culinary
herbs are those whose fresh or dried leaves are used in cooking;
some common culinary herbs are basil, French tarragon, rosemary
and thyme. Culinary
herbs are usually distinguished from spices, although the two
categories overlap. Culinary herbs generally consist of fresh
or dried leaves, while spices are seeds, roots, fruits, flowers
and bark. Culinary herbs usually have a mild flavor, while spices
tend to have a stronger, pungent flavor. Several common spices
are cinnamon sticks, anise seeds and ginger roots. This fact
sheet discusses primarily the common culinary herbs for home
gardens and landscapes. The
beginning herb gardener might want to start by growing herbs
such as basil, chive, dill, oregano, parsley, sage and thyme.
These herbs can be grouped in "classic" herb gardens, and can
be incorporated into flower beds or vegetable gardens. Most
herbs will grow well with the same sunlight, fertility, soil,
growing conditions, and cultural techniques required by vegetables
grown in the Northeast. Gardeners should pay special attention
to drainage and moisture requirements of certain herbs, since
many are very sensitive to soil moisture conditions. Sage, rosemary
and thyme require a well-drained, slightly moist soil, whereas
parsley, chervil and mint grow best on soils which retain moisture.
Raised beds may provide the necessary moisture and drainage requirements
for herbs that require good soil drainage. Basil,
French basil or sweet basil (Ocimum basilicum) is a popular,
tender, annual herb. Basil is native to India and Asia and is
grown for its aromatic leaves, which are used fresh or dried
as a flavoring. Basil can be direct-seeded or transplanted to
the garden in late spring, after all danger of frost is past.
The seeds normally germinate in 8-14 days. Basil requires full
sun and prefers moist and well-drained soil with a pH of 6.0.
Typical spacing for basil is 12 inches between plants and 24
to 36 inches between rows. Basil
grown for dried leaves or essential oil is cut just prior to
the appearance of flowers. The foliage should be cut at least
four to six leaves above the ground to allow for regrowth and
a subsequent crop. Japanese beetle, Fusarium and powdery mildew
are potential insect and pest problems on basil plants. Chives, Allium
schoenoprasum, are perennials native to the Orient. Fresh
leaves are excellent for making herbal vinegars and butter
and the blooms can also be used in herbal vinegars. Chives
are often used in salads, soups and cheeses. For successful
germination, chive seeds require darkness, constant moisture
and a temperature of 60 to 70 degrees F for best results. Sow
seeds 1/2 inch deep in pots or flats; germination will occur
in 2-3 weeks. Transplant seedlings to the garden when they
are 4 weeks old. Chives reach a height of 18 inches and a width
of 1-2 inches the first year from seed; they will spread to
10-14 inches in subsequent years. Chives require full sun and
well-drained soil with a soil pH of 6.0. Chives have beautiful
purple blossoms and will reseed prolifically if allowed to
go to seed. To harvest chives, cut leaves 2 inches above the
ground. Although no serious pest or disease problems are common,
both downy mildew and rust can infect chives. Dill: Dill, Anethum
graveolens, is native to the Mediterranean area and southern
Russia. Dill is a hardy annual, sometimes grown as a biennial.
Dill is commonly used as a seasoning for soups, fish, and pickles.
Butterfly larvae feed on dill, making it an ideal plant in
butterfly gardens. Dill should be direct-seeded in spring;
allow 10 inches for each plant. Since dill has long tap roots,
it should not be transplanted. Fresh leaves should be harvested
before flowering begins. Harvest seeds as soon as seed heads
are brown and dry. Dill does not have any serious pest or disease
problems, although phoma blight, rusty root and stem rot have
been reported. French
tarragon, Artemisia dracunculus, originates from southern
Europe (Russian tarragon, Artemisia dracunculoides, is
much coarser, has paler leaves, and a more bitter taste). French
tarragon is a woody perennial that will grow 2 feet tall. It
produces few seeds, and must be propagated by stem cuttings or
division. Plant in full sun in rich, well-drained soil with a
pH of 6.9. Divide the plants every three to four years. Harvest
six to eight weeks after planting and until leaves turn yellow
in the fall. French tarragon is prone to root rot in heavy and
wet soils. Mints, Mentha spp.,
are a group of herbs that are mostly native to Europe and Asia.
Some are indigenous to South America, America and Australia.
European and Asian mints are naturalized throughout North America
from southern Canada to Mexico. With the possible exception of
Corsican mint, mints are such rampant growers that they will
quickly overwhelm other plants. Invasive mints should be planted
in sunken clay pots to inhibit spreading. Japanese
mint (M. arvensis var. Piperescens), peppermint (M.
xpipita) and spearmint (M. spicata) are the most commonly
cultivated species of mint. All mints can be propagated by cuttings
or seeds. Peppermint does not produce viable seeds and can only
be propagated by cuttings. Mints can be planted in full sun or
partial shade and require rich, well-drained soil with a soil
pH of 6.5. Mint can be harvested almost as soon as it comes up
in the spring. Young, tender leaves and stems are the best. Mint
is susceptible to verticillium wilt, mint rust and mint anthracnose.
Spider mites, loopers, mint flea beetles, mint root borers, cutworms,
root weevils and aphids are all potential pest problems on mint
plants. Oregano, Origanum
vulgare subsp. hirtum (also referred to as O.
heracleoticum and O. hirtum), is native to the Mediterranean
region of Europe and central Asia. It is naturalized in the
eastern United States. Oregano is a perennial and can be propagated
by seeds. Direct-seed in the garden and do not cover seeds--they
need sunlight to germinate. Flavor can vary greatly among seed
propagated plants--propagate by root divisions or cuttings
from plants that are known to have strong flavor. Oregano reaches
a height of 12-24 inches and a width of 10-20 inches. It requires
a site with full sun and well-drained soil with a pH of 6.8.
Sprigs of oregano can be cut off when the plant is at least
6 inches high. In June, vigorously grown plants can be cut
back to the lowest set of leaves. Plants will generally leaf
out after two weeks and can be cut back again in August. Potential
pest and disease problems for oregano include aphids, leafminers,
spider mites and root rot. Rosemary, Rosmarinus
officinalis, is a tender perennial, hardy to zones 8 to
10. It is native to the Mediterranean region, Portugal and
northeastern Spain. Rosemary can be started from seeds, but
germination rates are very low. Use fresh seeds, preferably
less than two weeks old. Packaged seeds are difficult to germinate.
Start plants from cuttings or by layering from existing plants.
Rosemary grows slowly from seeds, and eventually reaches a
height of 72 inches and a width of 36-72 inches. Plant rosemary
in a sunny location with well-drained, slightly acidic soil.
Rosemary can be harvested year-round. Cut 4-inch pieces from
the tips of the branches, never removing more than 20% of the
growth at one time. Pest and disease problems of rosemary include
aphids, spider mites, scale, mealybugs, root rot and botrytis. Thyme, Thymus
vulgaris, is native to the western Mediterranean region.
It is a small, many-branched perennial shrub. Start seeds indoors
and transplant seedlings to the garden once all danger of the
frost is past. Thyme reaches a height of 12 inches and a width
of 10-12 inches. Thyme can be propagated from cuttings, by
layering and division. Harvest the entire plant by cutting
it back to 2 inches above ground in midsummer and again at
the end of the season. Pest and disease problems include spider
mites and root rot. Adapted
from Gary Gao and Brad Bergefurd, Ohio State University Extension,
2000
Pesticides
are poisonous! Read and follow all safety precautions on labels.
Handle carefully and store in original containers out of reach
of children, pets or livestock. Dispose of empty containers
immediately, in a safe manner and place. Pesticides should never
be stored with foods or in areas where people eat.
When trade names are used for identification, no product endorsement
is implied, nor is discrimination intended against similar materials.
Be sure that the pesticide you intend to use is registered for
the state of use.
The user of this information assumes all risk for personal injury
or property damage.
For more
information, call the URI CE Gardening and Food Safety Hotline
at 1-800-448-1011 or (401)874-2929 from outside Rhode Island;
Monday-Thursday between 9 am and 2 pm.
University
of Rhode Island Cooperative Extension provides equal program
opportunities.
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