HERBS & SPICES REFERENCE - GENERAL CULTURE

Light. Most herbs are easy to grow, but you must select the proper location to grow them. Most herbs need a sunny location, and only a few, including angelica, woodruff and sweet cicely, are better grown in partial shade. The oils, which account for the herbs' flavor, are produced in the greatest quantity when plants receive six to eight hours of full sunlight each day. If you don't have a good, sunny location, many herbs will tolerate light shade, but their growth and quality will not be as good.

Soil. Herbs will grow in any good garden soil. The soil should not be extremely acid or alkaline; a soil nearly neutral is best for most herbs. A pH reading between 6.5 and 7.0 produces the best herbs.

Most herbs do not require a highly fertile soil. Highly fertile soils tend to produce excessive foliage that is poor in flavor. Herbs grow best when soils have adequate organic matter.

In preparing average soils, add several bushels of peat moss or compost to each 100 square feet of garden area to improve soil condition and help retain moisture.

Drainage. When selecting a site for an herb garden, you must consider drainage. None of the important herbs grow in wet soils, but a few, such as mint, angelica and lovage, thrive in fairly moist soils.

If the only area available is poorly drained, you need to modify the area. Build raised beds or install underground drainage tiles to grow herbs successfully.

Preparation. Once you select a site, cultivate the soil to a depth of 12 to 18 inches, then level it. If only a shallow layer of topsoil exists above hard subsoil, remove the topsoil temporarily. Break up the subsoil, adding organic matter. After improving the subsoil, put it back. Even though the topsoil may be better than the subsoil, the topsoil may also need additional organic matter.

Pests. Few insects or diseases attack herbs. In some localities, rusts infect mints. In hot, dry weather, spider mites damage some herbs.

Aphids attack anise, caraway, dill and fennel. Grasshoppers and certain caterpillars attack herbs when conditions are right. Control is usually not necessary until you notice a problem.

Propagation: seeds. You can grow many herbs from seeds. If possible, sow the seeds in pots or flats indoors in late winter. They need a sunny window and cool temperatures (60°F) for best growth. Treat young plants for the garden just as you would treat young salvia or pepper plants.

Because some plants take longer than others to develop, start those with smaller seeds first, preferably in February. You may later transplant them into individual pots and plant them in the garden after danger of frost is past. The finer the seeds, the shallower you should sow them. For directions on starting seeds indoors see Missouri Univesity publication G06570, Starting Plants From Seeds.

A few herbs do not transplant well. Sow them directly into the garden. Plant anise, coriander, dill and fennel directly in the garden and don't transplant them.

For direct seeding outdoors, plant in spring after all danger of frost is past and the soil is beginning to warm up. Make the soil into a fine, level seed bed. As a general rule, sow seeds at a depth of twice their diameter.

Propagation: cutting, division, layering. Some established herbs multiply asexually by cutting, division or layering.

Layering is suitable for many perennials with flexible branches. Division works well for tarragon, chives and mint. You can propagate lavender, lemon balm, scented geraniums, sage and rosemary from cuttings. Information about taking cuttings and rooting them is available in Missouri University publications G06560, Home Propagation of House Plants, and G06970, Home Propagation of Garden and Landscape Plants.

You can take cuttings of herbs any time during late spring and summer from healthy, well-established plants. Those taken in fall take longer to root. Healthy tip growth makes the best cuttings. Cuttings of vigorous soft shoots or old woody stems are less desirable.

Cut just below a node to form a cutting that is 3 to 5 inches long. Most herbs should root in two to four weeks. After rooting, winter them over indoors in pots on a sunny window or in a cold frame. Plant them outdoors in a permanent location the following spring.

Division is useful for multiplying healthy, established plants that may be two to four years old. Division allows modest increase for plants like chives, mints and French tarragon. Divide herbs in early spring before growth begins. Dig up the old plant and cut or pull it apart into sections. Replant the sections and keep them moist until the new plants are established.

Layering is the simplest and most reliable method to increase perennial herbs such as thyme, lemon balm, winter savory, sage, bay and rosemary. The basic principle is to produce roots on a stem while it is still attached to the parent plant. After you root the stem, detach the new plant from the parent. Select a healthy branch that is growing close to the ground and that is flexible enough to bend down to the soil. While holding the branch close to the soil, bend the top 6 to 10 inches of the stem into a vertical position. It may be helpful to scrape the bark on the underside of the branch at the bend. Bury the bent, scraped portion 3 to 6 inches deep, and anchor it with a wire loop. Insert a small stake to hold the top upright. Water thoroughly.

You can layer anytime from spring to late summer. Allow the rooted shoot to remain in place until the following spring. Then cut it from the parent plant and plant it into the desired location.

Winter protection. Many herbs suffer winter damage in our climate, so some winter protection for perennial herbs is advisable. Many herbs have shallow roots that heave out during spring thawing and freezing of soil. A loose mulch spread over the roots about 4 inches deep can provide adequate protection. Evergreen boughs, straw or oak leaves are good materials for a mulch. Don't mulch until after the ground is frozen in early winter. Do not remove mulch until you see signs of new growth in the early spring. If the mulch compacts during the winter from heavy snows, fluff it up in early spring before growth begins.

Growing Herbs at Home    General Culture    Harvesting Herbs    Herbs Indoors    Herb Descriptions

Unless otherwise noted, all facts are supplied by Ray R. Rothenberger, Department of Horticulture, University of Missouri-Columbia.