Herbs are a big group of plants with the two largest groups being medicinal and culinary. Many of these herbs are Old World plants from the Mediterranean regions of Europe and North Africa. These wonderful plants have attached themselves to humanity and been grown for hundreds, if not thousands of years, for their essential oils.
I use these multi-purpose perennials in my waterwise plantings for their aromatic foliage and flowers (on the plants and in my food) and for their love of hot, sunny and dry planting sites. They are also indispensible to pollinators like bees and butterflies for their nectar and pollen rich flowers. Your bee-keeper friends will love you for planting big patches of these plants. My favorite herbal genera include the Lavenders (Lavandula), the Sages (Salvia), Catmints (Nepeta), Oregano (Origanum) and Rosemary (Rosmarinus).
Lavender is at the top of my list. I keep my lavender plantings in bloom by planting a mix of late-spring/early-summer blooming English varieties (Lavandula angustifolia) and summer blooming French hybrids (Lavandula intermedia). And if you plant re-blooming English types, like ‘Sharon Roberts’, ‘Pastor’s Pride’and ‘Buena Vista', you can stretch the flowers into September! For cold hardiness, the best of all the Lavender varieties is the heirloom variety ‘Vera.’,
Little Leaf Culinary Sage (Salvia officinalis 'Minimus') is another favorite that is often overlooked by gardeners. I love this durable perennial for its profuse display of deep lavender-blue late spring flowers and its beautifully fine-textured, gray leaves that look great all season long. Plant it alongside the brilliant deep green Rosemary ‘Arp’, one of the most cold hardy cultivars of this fragrant perennial. The ornamental Oregano (Origanum) are unfamiliar to many gardeners. Rectify this oversight by planting ‘Rotkugel Ornamental Oregano’, a superb grower with large, loose heads of bi-color flowers with dark purple calyces and deep pink flowers. The plant forms low-spreading mats that bloom from August through October.
These glorious herbs are most at home in USDA zone 5 to 10 areas of the western US where the arid climates and ample sunshine are most like their native lands. In areas of the country where there is more precipitation (more than 18-20 inches of water annually) and high summer humidity, the key to growing these perennials is to provide them with a fast draining soil and plenty of air circulation. Air circulation is improved by planting them with space between neighboring plants and in beds not enclosed by solid fences and walls. Fast drainage is best accomplished by planting in sandy or gravelly soils and/or on a south- or west-facing slope or in a raised bed. Mulching to a depth of 2 inches with crushed gravel helps to keep the crown dry and prevents water splashing onto the foliage.