Herb Gardening 101
Courtesy of Sal Gilbertie, owner of Gilbertie's Herb Farm in Easton, Connecticut, the largest herb operation in the United States, and author of several books on herb gardening and Robert Nuss, Ph.D., professor of ornamental horticulture at Pennsylvania State University, here's a prospectus on herb gardening that will help a greenhorn grow a garden full of nine herbs with a multicultural flair―parsley, basil, oregano, thyme, rosemary, cilantro, sage, mint, and tarragon. Let's get growing! Here's how.
Know your zone. Most herbs will grow in all parts of the United States. But you'll need to know something about your local climate to figure out when to plant particular varieties. The country is divided into 11 regions, or growing zones. To find out which one you're in, call your state's Cooperative Extension System, located in the county-government pages in the phone book. Also, ask for any materials they might have on herb gardening in your zone.
Go south. Locate the garden bed in the southernmost sunny spot of your yard to make sure your herbs get at least six hours of sun each day. Sunlight forces the plants to produce the oils that give them their flavor.
Let them breathe. Breezy conditions help keep plants drier and discourage the growth of fungus, the bane of herb gardeners. Plant 12 to 18 inches from the nearest fence, wall, hedge, or other high barrier.
Think high and dry. Planting your garden in a raised bed 10 or more inches off the ground will help ensure good drainage, which is essential to the good health of herbs. Gilbertie suggests filling the bed with two parts each of sterilized topsoil, peat moss, and sand or fine gravel. You should end up with a slightly acidic or near-neutral pH―the ideal environment for most herbs.
Get tested. Even if you create a raised bed, a soil test is a good idea. Check with your county extension service for information on soil testing in your area; you can also buy a do-it-yourself kit (available at most garden centers). You'll want your soil to be about 6.5 to 7 on the 14-point pH scale. Soil that's too acidic (below 6.5) needs lime; sulfur, peat moss, pine needles, or oak leaves can balance soil that's too alkaline (above 7).
Start small. Ambition can do you in, so keep your first garden a manageable size, Nuss suggests. The nine herbs in our garden should thrive in a 4- x 6-foot space. Make sure to allow for stepping stones or a path through the middle of the garden so you can harvest and weed easily.
Skip the seeds. For your first garden, buy transplants instead―you'll have a better chance of success. Choose plants that are true to color, that aren't overgrown in their pots, and that show no signs of rot or fungus at the base. Two or three plants of each should keep a small family stocked, but buy according to your tastes. You may be able to get by with one thyme and one rosemary plant, for example; go heavy on the basil if you plan to make pesto.
Down in front. Smaller herbs such as oregano, parsley, and creeping thyme belong in the south (or front) part of the garden so they're not shaded by taller plants such as basil, tarragon, and cilantro.
Give 'em room. In general, allow 18 inches between plants. Some will need more room―particularly perennials, which come back every spring and therefore get larger each year. Consult a reference book on herbs, or ask your local grower about the spreading pattern and shape of the plant before you dig.
Make a blueprint. Draw your garden design to scale on a sheet of graph paper; include any permanent structures such as trees, shrubs, or walls in addition to where you plan to place your herb plants. Because they will be permanent, place your perennials―oregano, thyme, rosemary, sage, mint, and tarragon―first. Fill in around the perennials with the annuals―basil and cilantro, which are replanted every year―and the only biennial in our group, parsley.
Hide the pot. Some herbs, like mint, can take over a garden. Keep a handle on them by planting them first in a large plastic pot about 12 inches in diameter and 12 inches deep. Then plant the whole thing in your garden, leaving about an inch of the rim above the topsoil. Use the same technique (but hide the rim completely) to make it easier to bring herbs like rosemary inside during the winter without damaging their roots.
Add an inch or two of mulch. It will stifle the growth of weeds, help keep your herbs clean, insulate them in the winter, and protect the soil from baking around the roots during the summer. Gilbertie suggests using peanut hulls or salt hay; avoid pine-bark mulch and grass clippings because they tend to make your soil more acidic. And be careful not to mulch too heavily at the base of your plants, or they may rot.
Feed sparingly. Generally, all perennial herbs need is a good spreading of manure or all-purpose, slow-release commercial fertilizer worked into the soil before planting and then again each spring. But the annuals, basil and cilantro, will produce much better if you feed them a little more often.
Water in the morning. "Herbs prefer to be dry." Gilbertie says. "Watering them in the morning gives them all day to dry out." Night waterings may encourage the growth of fungus.
Use the soup-can trick. Generally, herbs need only about an inch of water per week (more after you first plant them and during times of severe heat and drought). How to measure: Place several soup cans among your herbs, and check your watch when you turn on the soaker hose or sprinkler. When the water level in the cans hits an inch, check your watch again―that's how long it will take for you to give your plants a proper shower.
Harvest often. "The more you pick, the more you get," Gilbertie says. If your annual plants―basil and cilantro―flower and produce seeds, they'll quit growing leaves. Harvest them in the morning, when the herbs' oils are at their strongest. And clip the skins instead of plucking individual leaves off the plant.
Keep a record. Jot down vital information―which herbs you plant, when you planted them, and how often you water and fertilize them, for instance. "A diary is a great way to measure your successes and keep from repeating your failures," Nuss says.