Cold-hardy Mediterranean Perennial Border

How to use cold-hardy perennial plants from the Mediterranean area in your garden borders.

Origanum libanoticum
Item # 73050 		Origanum libanoticum
Cascading Ornamental Oregano

each $5.99
3 to 6 $5.79
7 or more $5.59
Veronica liwanensis
Item # 97340 		Veronica liwanensis
Turkish Speedwell

each $5.29
3 to 6 $4.99
7 or more $4.79
Helianthemum 'Ben More'
Item # 55070 		Helianthemum nummularium 'Ben More'
'Ben More' Rock Rose

each $5.29
3 to 6 $4.99
7 or more $4.79
Digitalis obscura
Item # 43345 		Digitalis obscura
Narrow Leaf Foxglove

each $5.99
3 or more $5.79
Anacyclus depressus
Item # 17210 		Anacyclus depressus
Mt. Atlas Mat Daisy

each $4.99
3 to 6 $4.79
7 or more $4.59
Artemisia abrotanum 'Tangerine'
Item # 22640 		Artemisia abrotanum 'Tangerine'
Tangerine Southernwood

each $5.29
3 to 6 $4.99
7 or more $4.79
  • Topic: Cold Hardy Gardens
  • Keywords: borders, exotic plants, groundcovers, perennials, Garden Design, gardens
  • Date: November 2000

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For years Mediterranean perennials like creeping Rosemary have been used prominently in mild winter areas like coastal California. Now, with the increasing availability of cold hardy cultivars and new species introductions, we are able to expand the use of these attractive plants into the colder areas of the western US (USDA zones 4-7).

Mediterranean perennials are native to the land areas of southern Europe, western Asia, the Middle East and north Africa that surround the Mediterranean Sea. They are valued in the garden for many reasons. As ornamentals they have both brightly colored flowers and attractively textured foliage in an endless number of green, gray and blue hues. In cultivation these plants are xeric, well adapted to heat and poor quality soils and are generally low maintenance, resisting attack from insects and browsing mammals.

As a general rule, Mediterranean plants are most colorful in the spring and early summer months reflecting the winter moisture/summer drought conditions of their native habitats. Of course, this is the easiest time of the year to have a colorful garden regardless of where the plants originate. It is during the heat of summer and changing of the seasons in fall that the Mediterranean perennial border really distinguishes itself from the rest of the garden. Once the Mediterraneans go out of flower we are better able to appreciate the foliar tapestry that these plants create.

As I gathered my thoughts and plant materials, I began preparations for the new Mediterranean section of my Xeriscape Demonstration Garden during the spring of 1998. The new bed was rototilled to a depth of 1 foot and my crew incorporated compost, YumYum Mix and Planters II trace mineral fertilizer into the native clay soil. During the fall of 1998, I began planting the 100 foot long bed along the garden’s western edge. After planting, I mulched with a thick layer of 3/8 inch crushed gravel to conserve soil moisture, capture water from sudden summer thunderstorms, and protect the crowns of the plants from extended periods of winter dampness.

In a perennial border, there are three height levels that we need to fill to achieve a balanced planting. Along the edges of the bed and between the other taller plants, groundcovers hold the garden together and guide the eye away from the path into the rest of the bed. Moving toward the middle, mounding plants link the edges with the tallest plants in the center or back of the bed. The tallest plants will occupy either the center of an island planting or the back of a bed that’s located against a wall or building. To plan this new perennial garden, I made a list of all the plants that I wanted to include in the planting and separated them into these three categories.

The guiding principle I used when planting this garden was to contrast the textures and foliage colors of each plant with its neighbor. Although I did try to choose plants with yellow, white or blue flowers, flower color actually took a back seat when deciding where to put each plant. For example, gray leaves mounders went next to tall olive-green specimens while silver groundcovers with short thin leaves nestled up to large leafed gray-green mounding plants. The resulting planting is very pleasing and one of subtle drama.

Groundcovers

I often use groundcovers. My favorites include:

Mounding Perennials

Included in this group are:

Tall Perennials

  • Spanish native foxglove Digitalis obscura is a standout with its finely textured evergreen foliage and unique brown/orange flowers.
  • Phlomis russeliana (Hardy Jerusalem Sage) is an architectural marvel with its showy whorled spikes of yellow flowers and large, fuzzy olive-green leaves.
  • Artemisia abrotanum ‘Tangerine’ lends a soft look to the border with its lacy, fragrant deep green leaves.

Ornamental grasses provide the final touch to any perennial border adding height, texture and long lasting ornamental seed heads. Two showy tall growing specimen grasses are:

  • Blue Avena grass (Helictotrichon sempervirons)
  • Stipa gigantea (Giant Stipa grass)

Culinary and Ornamental Herbs

Another essential category of plants for any Mediterranean border would be the culinary herbs. Many of the cooking herbs originate from the Mediterranean and include Salvia (the Sages), Thymus (the Thymes), Lavandula (the Lavenders) and Rosmarinus (Rosemary). These plants are fragrant, evergreen and taste great.

Among the Sages large-leafed “Berggarten” and the finely textured ultra-tough dwarf “Minimus” are two favorites. The Thymes provide both groundcover (non-culinary) and mounding (culinary) plants. My favorites in this genus include groundcover Woolly Thyme, “Pink Chintz”, “Doone Valley”, and mounding “Ray Williams” (to 2 feet in height!).

The Lavenders are rich with superb varieties. The French (x intermedia) hybrids like “Grosso”, “Provence” and “Alba” are among the tallest Lavenders and should be placed accordingly. Hybrids of mixed origins like intensely fragrant “Silver Frost” and everblooming “Goodwin Creek Gray” should always be included in a list of mounding (medium height) varieties.

Also among the mounders are highly recommended English varieties (which are actually native to Spain) such as deeply colored “Mitcham Gray”, pink/white flowered “Mellisa” and dwarf “Nana”. An excellent new cold hardy Rosemary I really push is “Madaline Hill” a marked improvement in grace and disease resistance over more commonly available “Arp.”

Wildflower Bulbs

And last but not least, many of the most colorful spring blooming wildflower bulbs originate from this region of the world. Tiny species tulips, Iris, daffodils and crocus kick-off the growing season with their early spring blooming flowers. I have planted carpets of these little beauties into the perennial beds with excellent results.