Herbs thrive in our hot, dry climate. Some Mediterranean herbs thrive so well that they can take over the garden.
Those with gray green foliage or strongly scented oily leaves are notably vigorous. One artemisia or wormwood plant can grow 4 feet high and 6 feet wide. One prostrate or creeping rosemary plant will cover and smother any other plants within a 3-foot radius. Both artemisia and rosemary are great for erosion control, but problematic in small gardens.
Members of the origanum family (oregano, marjoram) are considered invasive; their strong root systems spread quickly and choke out other plantings. Even when contained in pots, the oregano or marjoram roots can shoot out the drain hole within a couple of months.
Artemisia and the ornamental sages can be kept to a maintainable size if branches are pruned back to 6 to 8 inches high every winter.
Culinary herbs can be reshaped as they are harvested in mid-spring when the aromatic oils in their leaves are at their peak. Pinch back growing tips on rosemary when the plants are small. Prune out side shoots on mature rosemary plants or shear them to a smaller size. Cut back oregano and marjoram to 2 or 3 inches high when in flower; they will quickly flush new leaves.
Plan on replacing perennial potted herbs (sage, chives, oregano, rosemary, thyme) annually and biennial herbs (parsley, cilantro) every two years.
Keep culinary herbs in pots near the kitchen if possible. They’re more easily available for a quick picking at dinner time, and regular cutting and picking will keep the plants smaller. The tender-leafed herbs such as basil and tarragon can be moved into the shade on hot afternoons. Pick off basil flower buds as soon as they form. If basil flowers are allowed to bloom, the leaves lose their sweetness and can develop a very strong odor and taste.
Culinary herbs and their flowers are easily and quickly dried in our low humidity. Hanging herb bunches upside down does help concentrate the oils into the drying leaves (a bit), but isn’t necessary. Just lay the bunches out on newspaper or paper towels on the patio table or the garden bench for a few days and the herbs will be dry enough to store. Herb flowers are edible as well.
There are some differences in taste between dried and fresh herbs. Dried oregano has a much stronger flavor than fresh. Mexican oregano has a different flavor than the Mediterranean varieties. Basil loses much of its pungency when dried and is best used fresh.
Herbs seldom suffer from pest insects since the aromatic oils in their leaves are natural pest insect repellants. Make sure though that no pesticides were recently applied near herbs meant to be harvested.
Herbs really don’t need fertilizing. Side dress herbs with a tablespoon or two of an organic compost or fertilizer only if signs of nutritional deficiencies are apparent.
Mediterranean herbs are well adapted to poor soils and near drought. Plant herbs in groupings on a separate irrigation timer and water when the top 3 inches of soil has dried.
Send Elinor Teague plant questions at firstname.lastname@example.org or email@example.com (“plants” in the subject line).