Wherever a plant lives, access to water is crucial. Plants cannot grow without water, they cannot photosynthesize without water, they cannot even stand up straight without water. Plants that live in regions where drought is common must therefore adapt and find ways to survive when water supplies run short. In areas with a Mediterranean-type climate, rainfall comes only in the winter, and plants must tolerate summer drought. Together with the Mediterranean itself, similar climates can be found in California, central Chile, the Cape of South Africa, and parts of Western Australia. All these areas are renowned for producing grapes (Vitis vinifera), a Mediterranean native that thrives wherever this climate type can be found.

Many plants native to Mediterranean regions are hardy here in the Puget Sound area and make great garden plants. Having evolved to tolerate summer drought, they readily adapt to our dry summers, reducing the need for gardeners to water. Drought-tolerant plants have adopted several strategies to reduce water loss, and a common one is to have gray or silvery leaves. The color comes from a dense coating of hairs, scales, or wax, and these surface textures provide several benefits. They reflect light, reducing damage from ultraviolet radiation and cooling the plant. They also reduce evaporative water loss by partially covering the pores of the leaves. Silvery leaves are easy to spot in the nursery, making it easy to find drought-tolerant plants. Great examples include lamb’s-ears (Stachys byzantina), Jerusalem sage (Phlomis fruticosa), and lavender (Lavandula angustifolia).

Top row: Cyclamen graecum, Madrone Arbutus, Sempervivum globiferum. Bottom row: Phlomis fruticosa, Pinus brutia, Stachys byzantina.

Other drought-proofing strategies include an annual life cycle, evergreen foliage, corky bark, succulence, and swollen roots. Annual plants grow from seed, flower, then set their own seed within a single growing season, escaping the dry season as dormant seeds. California poppies (Eschscholzia californica), desertbells (Phacelia campanularia), and snapdragon (Antirrhinum majus) are good examples. Evergreens include manzanitas (Arctostaphylos), madrone (Arbutus), cypresses (Cupressus) and palms (Chamaerops), and very little water escapes through the thick cuticles of their tough foliage. Corky bark is of course a characteristic of the Mediterranean cork oak (Quercus suber), but also olives (Olea europaea) and pines (Pinus), not only resisting water loss (cork is hydrophobic) but protecting from fire. Succulent plants store water in swollen stems, leaves, and/or roots, as in century plants (Agave), cacti, houseleeks (Sempervivum), and stonecrops (Sedum). Storing water underground keeps it cool and protects it from animals, so plant storage organs such as bulbs, corms, tubers and rhizomes are common in Mediterranean landscapes. Wild onions (Allium), crocuses (Crocus), cyclamen (Cyclamen) and bearded iris (Iris) utilize this approach.

While many Mediterranean plants thrive in our area, not all are hardy, so make sure to check hardiness zones before purchase. Drought-tolerant plants also dislike wet soils during winter, so only grow them in places with excellent drainage, such as in pots, rock gardens, raised beds, slopes and in areas with free-draining sandy soils.