Herb gardening is among one of the oldest types of gardening, and has recently become popular in home gardening. Why not? Herbs are among the easiest plants to grow!
Throughout time, many cultures have grown herbs primarily for their culinary and medicinal uses. Today, herbs are often classified according to their use as either culinary, medicinal, aromatic, ornamental, or household/industrial. In addition to the utilitarian uses, herbs make interesting and beautiful landscape plants, whether they are used formally in an herb garden or informally mixed into gardens with vegetables or added to a mixed border of annuals, perennials, shrubs, and trees. Herb flowers and foliage provide a beautiful palette of color and variation in texture and form. Herbs add an element of excitement to landscaping that no other group of plants do—they evoke the senses of taste, smell, and touch.
As a group of plants, herbs can be difficult to define. From a botanical definition, an herb is herbaceous—that is, it does not form woody tissue. Most gardeners, however, take a broader view of plants grown as herbs and include plants that have roots, stems, leaves, flowers, or fruits valued for their culinary, medicinal, aromatic, household, or ornamental uses. This definition encompasses plants that have woody stems, such as cultivated varieties (cultivars) of rosemary, thyme, and lavender, as well as some shrubs, trees, and vines. Thousands of herb plants are available on the market today, some of which have many cultivars.
Herbs are among the easiest plants to grow when given the appropriate environment. Gardeners should choose a planting site where herbs will thrive rather than just survive. Herbs are adaptable to a wide range of soil and growing conditions; however, many do not grow well in poorly drained soil and will quickly die in a wet site.
Herbs vary in their native origin, from the Mediterranean region to Europe and Asia; therefore, consider the plant’s native habitat when determining a planting site. Most annual and perennial herbs grow best in full sun, generally 6 to 8 hours a day. Herbs preferring a cooler climate than Australia's may simply have a shorter growing season here than in other areas. Some examples are cilantro, dill, anise, and other members of the Umbelliferae family.
There are some special challenges to growing herbs in Australia, including the heat, humidity, and soil. If you want to grow herbs that don’t grow well in our long, hot days, provide plants with partial or filtered afternoon shade. Space herb plants far enough apart so they get good air circulation and light. Crowded plants do not dry quickly and may develop disease problems. Plants particularly susceptible are gray plants with fuzzy, pubescent leaves, such as lamb’s ear, artemisia, sages, and others.
Because herbs must have well-drained soil to survive, If you have heavy clay soils it should be amended with compost, peat, or other organic amendments to improve drainage and air space for root growth. Raised beds and containers are excellent environments for drainage. Regions with sandy soils grow herbs easily.
Herbs are tolerant of many soil types but grow best in a neutral (6 to 7 pH), loamy soil amended with organic matter. Perform a soil test to determine soil pH and nutritional needs.
Incorporate organic matter and any needed lime as you break up the soil. Adding peat moss or any type of composted organic matter will increase soil aeration and aid drainage. After thoroughly incorporating organic material, rake the soil to remove rocks, weeds, or plant debris.
When direct-seeding, cover the seeds lightly with a shallow sprinkling of soil, or, as a rule of thumb, cover them no deeper than twice the seed diameter. Firmly tamp the soil for good seed-tosoil contact, and water using a fine mist or spray to avoid washing the seeds away. As the seedlings germinate and develop their true seed leaves, thin the plants to approximately 3 to 6 cm to avoid spindly plants that crowd one another.
You may want to start seeds that are expensive or have a long germination period in a greenhouse or a controlled environment indoors. Plant the seeds in mid- to late winter. Start the herbs in small containers such as peat pots, jiffy peat pellets, cell packs, or other containers designed for growing transplants. You can also use Styrofoam or cardboard cups or containers, but be sure to punch holes in the bottoms for drainage. Start by selecting a sterile, soilless growing medium of peat mixed with perlite or vermiculite. Make sure it is well drained to reduce the chances of seedling disease problems yet able to hold needed moisture. Make sure the seeds and seedlings get adequate light, either artificial or window light (but not full sun), and a controlled temperature between 16 and 21 degrees Celsius. Label the plants with their name and the planting date. Water the containers, and allow them to drain completely.
After the chance of frost has passed but before setting the plants out, harden off the young transplants by reducing the amounts of water and fertilizer. Move the transplants outside to a shaded area, and each day, gradually expose them to a little more sunlight, wind, and normal outdoor conditions. When the plants seem strong and healthy enough, transplant them to prepared beds or a garden. Tamp the soil and water the plants, making sure the plants are not deeper than in their original containers.
If plant parts are obtained during the right season, they will respond well to and can be produced faster through propagation. These methods include dividing, taking stem and root cuttings, and layering.
Herbs that are easily divided include chives, oregano, yarrow, mints, and other plants that spread by clumps or stolons (runners). During the winter months, when the plants begin dormancy, use a trowel or knife to pull apart or separate the plants into clumps. Before using this method of propagation, however, remember that some herbs that spread by stolons can be invasive if they are not grown in a contained area.
Some herbs can be propagated from stem cuttings at several times during the year. In the spring, take softwood cuttings by pruning back new shoot growth after it hardens slightly, and in the summer, take them after flowering when the new flush of summer growth has strengthened. For softwood cuttings, use a sharp knife or pruning shears, and take 6 to 12 cm cuttings, removing a few leaves from the bottom third of the stem. Take 12 to 20 cm semihardwood cuttings in the fall, and take 20 to 35 hardwood cuttings during the dormant season or in midwinter.
Place cuttings in a propagation bed under mist or in a container that can be covered and treated like a greenhouse environment. Use a soilless peat and perlite or vermiculite medium that contains a wetting agent or is well moistened. Dip the ends of the stems into a rooting powder. Insert about one-third of this bottom end into the potting medium. Firm the medium gently to ensure contact. Make sure the cuttings are shaded and misted each day to avoid wilting until roots form.
Herbs That Can Be Propagated from Stem Cuttings:
Though this method is used less often, some herbs can be propagated from root cuttings. Cut two or three root sections of a horseradish or comfrey plant, and plant them into potting medium. That’s all you need!
Herbs respond well to layering, which occurs naturally for some plants. To layer plants, place a rock on top of a branch, or dig a trench and mound the soil over part of a branch. Roots will form at the nodes having soil contact. This part can then be removed from the parent plant.
If you don’t want to propagate your own herb plants, you can, of course, buy them. Even the most inexperienced gardener can learn how to select healthy herb plants. Follow these tips when selecting an herb plant.
Remember, the best plant is not always the largest one.
Herbs require minimal fertilization. In fact, herbs often suffer from overwatering and overfertilizing rather than from not enough. If your soil test recommends that a complete fertilizer, such as 10-10- 10, be broadcast at planting, that may be enough nitrogen for the entire season.
Slow-release fertilizers can be used to help herbs establish. Many gardeners prefer to only use organic fertilizers such as manures. Organic fertilizers generally break down slower in the soil and have other benefits that help improve plant growth and soil.
Water herbs during dry periods. It is better to irrigate to maintain soil moisture to a depth of 20 to 25 cm than to lightly sprinkle the soil surface every day. Some herbs wilt faster than others and may require more frequent watering, particularly during hot weather and if grown in containers.
Try to remove as many perennial weeds as possible before planting a garden. Weeds compete for nutrients and water and in some cases can harbor harmful diseases and insects. Cover newly prepared garden soil with a layer of mulch to prevent weed seeds from germinating in the sunlight. Mulches also conserve soil moisture, keep plant roots cool during summer and protect plants during winter. A layer of organic mulch, such as pine straw or leaves, will be attractive as well as functional.
Pruning naturally stimulates plant growth. Pruning herbs can be as simple as pinching back growing tips to encourage branching; removing, or deadheading, spent flowers; or harvesting a major portion of plant growth for drying and preserving. Pinching back herbs throughout the growing season is the best way to maintain healthy, vigorous, attractive plants.
Prune branches just above a leaf node or above another branch where you want to force new growth to occur. It is important to deadhead herbs to keep plants growing and to encourage more flowering.
The best time to harvest herbs is when you are ready to use them. Using clipped sprigs from plants throughout the growing season is the easiest way to maintain herbs, so harvest only as much as you need each time. If harvesting large amounts, follow these guidelines.