Patty's Plant Picks: Upright Rosemary

Upright rosemary shrubs are blooming freely now, their pale blue flowers reminiscent of the clear skies we have been missing here in the Pacific Northwest. Both ornamental and edible, Rosmarinus officinalis has a great many assets that put it at the top of my garden wish list.

For one, rosemary is evergreen, with beautiful color and texture, so the shrub looks good in every season. It is an attractive vertical plant that can reach 6-8’ high, perfect for that upright statement in a garden. Rosemary blooms in winter and spring in colors ranging from blue to lavender to pink to white. Of course, rosemary has terrific aroma—place it along a walkway to enjoy its pine-like scent as you brush by, or snip off bits of this savory herb to use in cooking.

The evergreen leaves of rosemary are needle-like and plentiful. On top, the leaves are dark green, with white fuzziness on the underside. The abundant blue, pink, lavender, or white blooms are nestled between leaves and are also edible. The flowers attract hummingbirds, bees and butterflies to forage on them.

Bruising the foliage of rosemary releases a pleasing aroma, a bit like pine and sage. The flavor of fish, beef, pork, or vegetables is uniquely enhanced by the addition of rosemary during meal preparation. In addition to culinary uses, the leaves can be used in potpourri, and stems of cut rosemary make interesting additions to floral arrangements.

Rosemary can be used as a background plant, screening hedge, or solitary specimen. Its green spires, if not pruned regularly, can reach as high as 8’, although there are plenty of cultivars that are much shorter. Rosemary is also useful in outdoor pots, planted in the “thriller” role of the “spiller-thriller-filler” container combination. A 50:50 mix of potting soil to builder’s sand is just right for potting up rosemary. (Don’t use washed sand, as its particle size is too small for a potting soil.)

Rosemary plants need a fast-draining, not-too-rich soil, and plenty of sun. If your garden has lots of clay or boggy areas, this is not the plant to choose. A Mediterranean native, rosemary thrives best with little to moderate water.

The upright varieties are the hardiest, but will not likely survive a winter with prolonged or frequent temperatures in the teens. I cannot recommend the trailing 'Prostratus' plants, as I don't believe they will live through our winters at all. The most cold-hardy rosemary is ‘Arp’, named after a small town in Texas. This cultivar is 4-6’ tall and 2-4’ wide, with an upright habit. It features light blue to almost white flowers, and thick, gray-green leaves.

Although any variety of rosemary can be used in cooking, varieties with broader leaves have more of the flavorful aromatic oils that give the distinctive taste. Favorite culinary cultivars are 'Tuscan Blue', 'Blue Spires', 'Spice Island', 'Gorizia', and 'Miss Jessup's Upright'.

'Tuscan Blue': 6-7’ tall & 2-4’ wide. Leaves are wider than average and very aromatic; dark blue flowers. Great choice for screening, or carefree waterwise gardens.

'Blue Spires': 5-6’ tall & 3-4’ wide. Strong vertical habit; clear blue flowers; light grey-green foliage. A good choice if your gardening style is formal.

‘Spice Islands’: 4-6’ tall & wide. Very upright form; dark blue flowers. Named for its exceptional flavor as a culinary seasoning, either fresh or dried. 

'Gorizia': 4-5’ tall & wide. Upright, open form. Leaves are larger, longer, and brighter green than typical; pale blue flowers. Good “architectural” specimen or accent.

'Miss Jessup's Upright': 4-5’ tall & 2-3’ wide. Slender branches; pale blue flowers. Good choice for small gardens or containers.

Whether your garden is pocket-sized or sprawling, your style formal or wild, and you enjoy cooking with this savory herb or not, you’d do well to add this evergreen shrub to your landscape.

West Seattle resident Patty J Campbell is a botanist and garden authority with forty years experience in Western Washington landscapes.