Feature

Finding Success with Mediterranean Ornamental and Semi-Hardy Edible Plants

Semi-Arid Loving, Half Hardy(?), and Perfect Plants for Your Garden

Dr. Andy Pulte, Distinguished Lecturer (UT Plant Sciences) and Director of UT GATOP Arboretum and Education Center (Knoxville)

Commonly referred to as Mediterranean in origin, there is a somewhat confusing (and decidedly oversimplified) group of plants that come from a similar region of the world. What gardeners and the public may infer from the word “Mediterranean” is somewhat ambiguous, and in practical terms may be most associated with a climactic region that is most often associated with dry summers, mild winters, and lean soils. Parts of California certainly supply the conditions that are described as a “Mediterranean climate.” I often hear people suggest certain plants prefer “Mediterranean” type conditions. And in fact, it is true many of the plant species that we say prefer “Mediterranean” type conditions have originated from the Mediterranean basin, which covers portions of three continents (Europe, Asia, and Africa). For those of us who garden or sell plants in the Southeastern U.S., we know without a shadow of a doubt that we do not live in a Mediterranean climate. We commonly experience hot, humid summers and cool, wet winters. However, some edible, ornamental, and medicinal plants from the Mediterranean basin continue to be tried, and occasionally will thrive, and so are increasing in popularity in regional gardens. I have grown and enjoyed all of the plants that I will describe below. One plant not mentioned, Olive (Olea europaea) (Photo 1), which is the quintessential botanical indicator of a true Mediterranean climate, is not known to be reliably hardy in the southeastern U.S. However, I do keep an olive tree in a container as an example for students and drag it into our greenhouses at UT’s campus every winter.

Photo 1: Olive europaea

If you choose to add any of the following plants to your garden, or if you want to suggest them for customers, I have some basic recommendations. First, realize that most of these plants can be marginally hardy across the state. All species are worth growing, but these plants are also susceptible to the impacts of our regional climate. Second, all of the following plants perform best when planted in spring and placed in full sun after the soil has warmed and the fear of frost has passed. This timing will give the plants an entire growing season to establish before experiencing what winter may have to offer. Also, do not prune any of these plants as fall approaches or during the winter. If pruning is desirable, do so only after your frost-free date is well behind you (in Knoxville’s USDA Plant Hardiness Zone 7, May 1st is a safe bet). Lastly, when establishing new plants, I suggest planting slightly above grade and mounding soil up to their roots to reduce the chances of waterlogging the root zone. Or even better, try growing these plants in containers with increased drainage (note: plants in containers may have greater need of winter protection). All the following plants may not be “forever plants” in your garden or the gardens of your customers. However, you may get several years of enjoyment out of them before plants succumb to winter injury or our region’s high humidity.

As an example, right before Christmas 2022, an unprecedented cold snap killed or severely damaged many of the plants listed below. There is no reason to stop growing these plants altogether or stop promoting their use. In fact, past experience and all indications suggest that retail consumers and residential will want to replace these plants during spring 2023. So this cold snap provides a great opportunity to introduce consumers to species and cultivars that are known to thrive in our region.

Rosemary (Salvia rosmarinus)

Native Range: Africa, Europe (Portugal and N.W. Spain), western Asia

Rosemary becomes a woody shrub across time and can grow to 2 – 4' tall. Plant near sidewalks and walkways for passersby to brush as they move past. Many cultivars are being tested for cold hardiness, but ‘Arp’ is still the standard. ‘Madalene Hill’ which is also known as ‘Hill Hardy’ may be the second cold-hardiest rosemary we can grow. Flowers can be pink or white but are most often blueish purple. Flowering time is also cultivar dependent, with some blooming in spring and summer while others bloom in the fall or early winter. [Note: This plant species was formerly Rosmarinus officinalis.]

Photo 2: ‘Hill Hardy’ Rosemary

Photo by Andy Pulte

Bay (Laurus nobilis)

Native Range: Northern Africa, western Asia, southern Europe

Bay is most commonly known as the leaf you pick out of your soup, or crab boil, before you dig in to eat – bay leaf comes from an evergreen tree or large shrub known for its aromatic foliage. Bay is beautiful in a container that can be moved indoors for winter protection or can be planted in a highly sheltered spot. Laurus nobilis is truly a Zone 8 plant. I have seen specimens survive for several years when planted in just the right spot with good drainage where they may then grow to several feet in height.

Photo 3: Bay

Photo by Andy Pulte

Pomegranate (Punica granatum)

Native Range: Middle and western Asia

Possibly hardier than its typical Zone 8 listing, some Tennessee gardeners have started growing pomegranate not for its fruit, but its flowers. Plants grow as a multistemmed shrub with flowers that range between red, bright orange, and salmon-colored and can look like a small carnation on many ornamental cultivars. If temperatures go below 10ºF, plants are often killed back to the ground but will often persist and rebound from their existing root system.

Photo 4a: Ornamental Pomegranate

Photo by Bill Klingeman

Photo 4b: Dwarf Pomegranate

Photo by Bill Klingeman

Fig (Ficus carica)

Native Range: Western Asia, southeastern Europe

Fresh figs from your garden are a true delicacy, which makes fig a musthave plant for many Tennessee gardeners. Figs are large shrubs that sometimes reach over 15' high and wide. After mild winters when stems persist, gardeners are often treated to both a late spring and a fall crop of figs. There are many cultivars to choose from, but the best advice is to get several so you can expand your harvest window. Different cultivars will produce their fruits at slightly different times and also can provide a diversity of tastes to explore.

Photo 5: Fig

Photo by Andy Pulte

Common sage (Salvia officinalis)

Native Range: Spain, western Balkan Peninsula, Asia Minor, and northern Africa

Very commonly grown in Tennessee gardens, common sage is by far the hardiest of the plants listed, provided they are given good drainage. Common sage grows as a small, woody, sub-shrub that has more or less glaucous, wooly, resinous leaves. Many cultivars are grown as potherbs or spices, with others used strictly as ornamental plants. These are valuable garden additions when planted on the edge of a sunny border with good drainage.

Photo 6a: Sage

Photo by Andy Pulte

Photo 6b: Sage

Photo by Andy Pulte

English Lavender

(Lavandula angustifolia)

Native Range: Primarily Mediterranean climactic regions of Europe, Spain eastward to Italy

Not really originating in England at all, but English lavender was given that moniker by English gardeners. Many cultivars are sold, yet few persist well into the dogdays of summer. All selections require excellent drainage and good air circulation for success. We have all been impressed with the cultivar ‘Phenomenal’ which is actually a Lavandula x intermedia hybrid cross between English Lavender and Lavandula latifolia (Portuguese Lavender). To keep plants from becoming leggy, prune flowers off as they start to fade.

Photo 7: English Lavender