|Although many herbs are grown as ornamentals, most have culinary and/or medicinal properties.|
People have used herbs for their culinary and healing properties for many centuries. Today, herbs are as popular as ever, perhaps even more so. Cooks love the unique flavors that herbs— fresh or dried—lend to all kinds of food and drink. Herbalists treasure the healing qualities of certain flowers, leaves and roots. Herbal crafters preserve the beauty and fragrance of flowers and leaves in potpourri, wreaths, sachets and dried arrangements. And gardeners value herbs for all their excellent qualities, including their vigor, low maintenance and natural resistance to pests.
When most of us think of herbs, we picture the common kitchen seasonings—basil, rosemary, sage, thyme, and so on. Yet in the broadest sense of the word, an herb is any plant that is considered "useful" in some respect to humans. The leaves, roots, seeds, stems or flowers of an herb might be important as a source of flavoring, medicine, fragrance, dye or some other product. And just as we might consider any aggressive plant a "weed" when it is growing someplace where we don't want it, so an "herb" is any type of plant—annual, perennial, tree, shrub or vine—that has some practical value beyond looking beautiful in the garden.
Not that good looks don't count. In fact, gardeners regularly grow many useful herbs not so much for their culinary or medicinal properties, but simply because they work so well in the landscape. Unless you are a devoted herbalist, you probably don't use dried peony roots as a remedy for cold sores, or pick the leaves of betony (Stachys spp.) to use as a natural bandage (its other common name is woundwort).
Instead, we grow these "herbs" because we like having them in the garden as ornamentals. Yet exploring the useful properties of many of our favorite plants, though little appreciated in this modern consumer age, can add a whole new dimension to gardening and inspire a lifelong fascination with herbs.
Site and Soil
Most herbs grow best in a well-drained, moderately rich garden soil. However, some of the most popular herbs, such as rosemary, lavender, bay and winter savory, are woody plants native to the Mediterranean region. These herbs prefer a gritty, sharply drained soil. Good drainage is extremely important because standing water around the root crown of plants can cause them to rot. To keep these plants happy in garden soil that is particularly heavy or clayey, you will need to improve drainage either by adding lots of organic matter like compost, or by growing herbs in raised beds or containers.
Another crucial factor to consider is the amount of sunlight a plant needs to "see" every day. Most common herbs thrive in full sun conditions (six or more hours of direct sunlight per day). Don't despair, though, if you have a garden site that receives only partial sun (two to six hours per day). Many herbs will thrive with less sunlight; you just need to select the right types based on the amount of light they can expect to get in your garden.
Many herbs require full sun and warmth to grow well and to develop the essential oils that give them their pungent aroma and flavor. Raised beds are a good way to provide not only better drainage, but warmer soil, especially early in the season. Using stone or brick as edging for raised beds helps to reflect and retain heat in and around the herb garden.
Paving also works well to create a warmer microclimate for heat-loving herbs that are often grown in pots or planters, such as rosemary or bay, and for low-growing ground covers such as creeping thyme.
Like other plants, herbs can become stressed on an especially windy or exposed site. Growing herbs in beds near the house or next to other buildings or walls provides the plants with a warm, sheltering microclimate and increases a gardener's chances of success with tender perennials like rosemary, which is hardy only to Zone 8. Even if, like most American gardeners, you grow rosemary in containers and bring it indoors for the winter, it's still a good idea to set it out in a sunny, sheltered area, one that duplicates as closely as possible its native growing conditions.
Pest and Disease Control: For the most part, herbs are not affected by insect pests. The same essential oils that give herbs their appealing flavor and aroma make the plants unpalatable to bugs. This is why you'll see herbs touted as good companions for all kinds of vegetable crops and other plants. Some herbs, such as pennyroyal and tansy, can even be used as natural insect repellents in the home.
If necessary, handpick any insects you see damaging leaves, or remove any leaves that have become infested. Control aphids, spider mites, or whiteflies, if they appear, by spraying leaves (including the undersides) with an insecticidal soap.
Diseases are also rather rare with herbs, and are most often the result of plants being stressed—either because the plant isn't growing in the kind of conditions it needs (amount of sunlight, water requirements, adequate drainage, etc.), or because the plants are crowded together too closely. In the case of downy or powdery mildew, remove and destroy any infected leaves and try spraying plants with a compost tea.
Some herbs are easy to start from seed, whereas others take a long time to germinate and grow and usually are either purchased as plants from a nursery or propagated vegetatively from existing plants (by stem cuttings, layering or root division).
Popular herbs that are easy to grow from seed include basil, borage, calendula, chervil, coriander, dill, lemon balm, parsley and sage. Before sowing any herb, whether in flats or directly in the garden, check its specific germination requirements to see how early you'll need to start it and whether it requires any special handling (a period of cold dormancy, or stratification; light or darkness for germination; soil temperature; etc.).
Like other plants, most herb seeds should be planted at a depth of only about twice their thickness: with very small seeds, this means sowing on top of moistened soil in flats and gently pressing them in.
If you want to start new herbs from plants that you already have growing in your garden, there are several ways to do it, all of them variations of vegetative propagation.
Root division: For many hardy perennial herbs, root division is the simplest means of propagation. Using a garden fork, dig up the plant's root system and either pull the roots apart by hand (as with chives), or cut the root mass into several pieces and replant them elsewhere in the garden.
The best time to divide plants is in the fall, when they are winding down for the year. If divided and replanted at this time, new plants will establish themselves and get off to a good start the following spring. Placing transplants on a small mound of soil or compost in the bottom of the planting hole helps to prevent settling. Firm down the soil around the plants and water them well after planting to eliminate any large air pockets around the roots. Laying a thick organic mulch around plants in the late fall will help insure against crown heaving, which may otherwise occur as a result of freeze/thaw cycles over the winter.
Herbs that respond well to root division include bee balm, chives, garlic chives, horehound, lovage, marjoram, oregano, pennyroyal, sorrel, tansy, thyme, and sweet woodruff.
Cuttings: Stem cuttings of various herbs (hyssop, lavender, mints, oregano, sage, thyme) should be taken during the spring or summer, when plants are healthy and growing vigorously. Rosemary and tarragon tend to root better in the fall, so use them for cuttings at that time and grow them indoors over the winter.
1. Select stem segments that are tender (not woody) and about three to six inches long, with at least five leaves along the stem. Make an angled cut, just above an outward-facing leaf node.
2. Remove the lower leaves on the stem, dip the cut end in rooting hormone powder, and plant it deeply in a pot containing a soilless seed-starting medium mixed with moistened vermiculite or perlite.
3. Cover the cuttings loosely with a plastic bag to create humid conditions and place them in a cool (70 degrees F) location away from direct sunlight.
4. Monitor the plants and water if needed, or remove the plastic bag if there seems to be too much moisture. After a few weeks, start checking for new leaf growth, which indicates that the plants are rooting well. Repot the plants into larger containers filled with regular potting soil and gradually expose the plants to full light.
Layering: Layering involves burying a trailing stem of an herb plant, encouraging it to form roots, and ultimately creating a new plant. It works well with perennial herbs such as marjoram, rosemary, sage, and winter savory. The best time to do this kind of propagation is in spring (on last year's growth) or in summer (on this year's growth).
1. Select a stem that is long and trailing and that you can bend down easily to touch the ground.
2. Make a slanted cut halfway through the stem (or, with slender stems, scrape the outer surface). Place the cut part of the stem in a shallow depression just below the soil surface, holding down the stem on either side with lengths of metal wire (unbent paper clips are good for this). Cover the cut part of the stem with a little soil, and water well.
3. After six to eight weeks, brush away the soil and check to see whether the stem has begun to form a new root system. If it has, cut the stem that connects the new plant to the mother plant and transplant the new plant elsewhere in the garden.
Designing with Herbs
As a group, herbs are extremely versatile plants and lend themselves to a variety of garden styles and settings. The monasteries of the Middle Ages were famous for their medicinal herb or "physic" gardens, which in addition to leafy herbs included many flowering plants such as roses and irises.
By the 16th century in England, the "knot garden" had become a popular design for a formal herb planting, with a rectangular bed laid out in an intricate geometrical pattern. Inside the interlacing lines of herbs or miniature box (Buxus) hedges, small beds or compartments were each planted with a single variety of herb, often selected for its ornamental foliage.
Formal design elements: The intricate knot garden is still a beautiful way to grow herbs, but today most home gardeners find the heavy maintenance required to keep it weeded, pruned and looking good too formidable and time-consuming. However, if a formal herb garden fits with your house and landscape, you can incorporate some traditional design elements that will lend the appeal of a formal appearance without the high maintenance.
The most basic characteristic of all formal herb gardens is their use of a focal point, something that draws the eye to the center of the design. This center point is typically an architectural feature, such as a sundial, pedestal, column, birdbath, fountain or a decorative or distinctive pot. When planning an herb garden, start with this central focal point and work outward, defining beds with radiating paths that divide the garden into quarters (for a square or rectangle) or into pie-shaped sections for a circle or wheel design. The point of these formal designs is to set off each individual herb, rather than merging different types into an indistinct hedge or border.
Many kinds of perennial plants—both herbaceous and woody—can be used for edging in the formal herb garden, from shrubs such as southernwood (Artemisia abrotanum) and various evergreens to low ground covers such as creeping thyme (Thymus praecox). Another idea, especially if your soil is heavy or clayey, is to grow herbs in a number of neatly sided raised beds, organized in a geometrical pattern.
Paths or edgings made of bricks or other paving materials such as Belgian blocks add a nice formality to the herb garden. Paved paths provide easy access to the beds for maintenance and serve as walkways—plus, they are easier to maintain than traditional boxwood hedges. Another benefit of bricks is that they soak up and retain the warmth of the sun, something that is appreciated, especially in the cooler climates, by heat-loving Mediterranean herbs.
Informal Garden Ideas: Formal gardens are beautiful, but many people prefer to incorporate herbs into their existing garden spaces, among either ornamental or edible plants. Annual herbs such as basil and summer savory are natural partners for tomatoes and beans in the vegetable garden, while purple-leaved basil or calendula make good choices in an annual or mixed flower bed. Perennial herbs such as creeping thyme feel right at home in a rock garden, while taller plants such as hyssop (Hyssopus officinalis) and silvery wormwood (Artemisia absinthium) fit nicely into an ornamental border.
Another way of using herbs in the landscape is to combine fragrant plants to make a scented garden. First, find a sunny spot where you might enjoy sitting with your morning cup of coffee, or in the evening after dinner. Reserve a spot in or next to the garden for a wooden garden bench, or a table and chairs for outdoor dining and entertaining. Then select herbs of various heights and growing habits, whose scents will turn this spot into a pleasant area for reading, socializing, or private meditation.
So many herbs have a delightful fragrance that it's hard to limit yourself to just a few. Some excellent choices for the scented garden include English lavender (Lavandula angustifolia), lemon balm (Melissa officinalis), all kinds of mints, oregano, rosemary, scented geraniums (Pelargonium spp.), costmary (Chrysanthemum balsamita), and dame’s rocket (Hesperis matronalis), whose flowers release a delightful clovelike aroma in the evening. Plant fragrant ground covers such as creeping thyme (Thymus praecox) and Roman chamomile (Chamaemelum nobile), perhaps in gaps between flagstones or other large, flat paving stones set around the area.
Gardeners who are interested in naturalizing herbs in a somewhat wilder setting can select from a wide range of hardy plant species. Certain herbs are aggressive and vigorous, fitting better into the landscape at large than in a mixed bed or border, where they can quickly crowd out other plants. Examples include various mints (Mentha spp.), elecampane (Inula helenium), comfrey (Symphytum caucasicum), tansy (Tanacetum vulgare), and soapwort or bouncing-bet (Saponaria officinalis). Look around your property and see what kinds of sites and soils you have; you’re sure to find niches that offer the perfect conditions for some of these wilder herbs to thrive and spread.
Growing herbs in containers: Growing different types of herbs in containers is a great idea for several reasons. First of all, you can grow tender perennials like rosemary and flowering sages all year long, bringing the pots indoors as days shorten and temperatures dip in the fall. Secondly, growing in containers gives you the flexibility to move plants around outside and display them to best effect. Containers also are a boon for gardeners who have poorly drained soil or limited growing space.
The soil you use in containers should be well-drained; regular potting soil amended with perlite and vermiculite will suit most plants. As with other plants in containers, herbs require regular watering and fertilization throughout the growing season. Plants like rosemary can tolerate fairly dry soil between waterings, but other herbs with broader leaves need more attention to watering when grown in pots. Adding finished compost or peat moss to the soil mix when you are potting plants will help the soil retain moisture.
During the outdoor growing season most potted herbs can be fertilized as frequently as once a week. Use a liquid fish or seaweed emulsion or a complete liquid fertilizer. Once you bring plants inside for the winter, they require much less fertilization; once or twice a month is sufficient. Especially after plants are inside, it's important to practice "flush watering" regularly; in other words, keep adding liquid until you see water running out of the bottom hole in the pot and into the tray beneath. This prevents fertilizer salts from building up in the soil.
Herb plants that can live for several years in pots include rosemary, lemon verbena, bay laurel and scented geraniums. Some long-lived herbs can be pruned and trained into interesting topiary shapes or ball-headed "standards," which makes them valuable as formal accents on a patio, entrance, or walkway during the summer, and as houseplants during the cooler months of the year. Check plants periodically to see whether they need to be repotted into a larger container.
During the winter, the best place for herbs is inside the house next to a cool, sunny window, where they can get about three or four hours of direct sunlight every day. Conditions inside most houses during the winter months are dry, so mist plants or place them in trays on top of watered pebbles to increase the humidity level.
Plants that you bring inside for the winter invariably experience some insect problems. This is frequently due to the stress of being moved into an indoor environment and new growing conditions. The best way to minimize this stress is to dig and pot up plants at least a couple of weeks before the first frost, then acclimate them gradually to indoor conditions, perhaps by moving them to a porch or breezeway (a reverse process to the hardening-off that you do in the spring with plants started indoors). Watch the plants closely for the first few weeks inside, and pamper them by providing plenty of water and misting them.
Even given this tender loving care, some herbs will become infested with insects. If you shake a plant and see a cloud of whiteflies, it's a good idea to set the plant in the shower briefly and wash the insects off the leaves. Then spray the plant with an insecticidal soap or hot pepper wax. Follow label instructions and repeat treatments as needed. Scale and mealybugs can be controlled with an alcohol-soaked swab.
Harvesting and Preserving Herbs
The uses for herbs, and the number of products and recipes that can be made with them, are practically endless, including herbal recipes, crafts, gifts and other items. One topic of interest to gardeners, cooks, and crafters alike is when and how to harvest herbs, and how best to preserve them so that they retain as much of their flavor and fragrance as possible.
In almost all cases, the best time to harvest herbs is when the plants are forming buds, but before they have flowered. At this time, the plant's leaves contain the highest concentration of essential oils. A few exceptions include lavender, which is valued mostly for its flower buds, and herbs like calendula and chamomile, which are harvested for their flowers.
Probably the easiest and most common method of drying various kinds of herbs is to cut back whole stems of plants and bunch a dozen or so together, securing them with a rubber band at the end. Then bring them into a warm, dry place out of direct light and hang the bunches up from hooks or rafters to air-dry. Leaves should be crisp and dry in seven to ten days, at which time you can take down the bunches and strip the leaves from the stems over a newspaper or large tray, discarding any debris or leaves that look discolored. Pour the herb leaves into tightly sealed jars or other containers, label them, and store them in a cool, dark place.
Not all herbs will air-dry successfully in this way. Basil, for instance, tends to turn brown and lose a lot of its pizzazz when hung up in bunches. An alternative to bunch drying is to place herbs on a drying rack in a just-warm oven, or in a dehydrator, which will dry leaves more quickly than simply hanging them up.
Even faster is to spread herbs between paper towels in a single layer and place them in a microwave oven. In her book Living with Herbs, Jo Ann Gardner recommends zapping herbs in the microwave for two minutes, then taking them out and checking them. If the leaves aren’t crisp-dry, she puts them back in the microwave and zaps them for additional 30-second intervals until they are done. Microwaves and leaf thickness may vary, so this method requires some experimentation.
Finally, a neat alternative to drying some herbs such as parsley, chervil, and basil for use as seasoning is to place two cups of fresh herbs in a blender with one cup of water or ¼ cup of olive oil and then process them. Pour the resulting slurry into ice-cube trays or a plastic bag and freeze. These herbs they can be taken out as needed and used as seasonings in soups, stews and other recipes.