1. ‘Big Blue’ Sea Holly

Name: Eryngium ‘Big Blue’

USDA Hardiness Zones: 4 to 9

Size: 28 to 30 inches tall and 15 to 18 inches wide

Conditions: Full sun; sandy to average soil

‘Big Blue’ sea holly is the perfect plant for our challenging conditions. Hail and drought do not affect it, and it loves sun and lean soil. The plant’s form alone is dramatic enough but then it adds the blue flowers, which extend up the stem and finish with a spiked 4-inch-diameter collar. This is a nonstop bloomer from its first flower in midsummer until early autumn. Deer and rabbits avoid it, but bees swarm the blooms.

2. ‘John Davis’ Rose

Name: Rosa ‘John Davis’

Zones: 3 to 9

Size: 6 to 8 feet tall and 6 feet wide

Conditions: Full sun; loamy, well-drained soil

‘John Davis’ is considered one of the best of the Explorer series roses (hardy roses bred in Canada). Its blooms have the character of an old-fashioned rose. The plant loves to climb. It has a high resistance to disease and requires minimal pruning. ‘John Davis’ blooms freely throughout the season, with the first flush having clusters of up to 17 flowers each. It leaves one with the sensation of being enshrouded in a softly sweet cloud of pink.

3. New Millennium Series Delphiniums

Name: Delphinium cvs.

Zones: 3 to 7

Size: 3 to 6 feet tall and 2 feet wide

Conditions: Full sun; fertile, well-drained soil

New Millennium is a series of hybrid delphiniums from New Zealand selected for heat tolerance, cold hardiness, and longevity. Started from seed in January, they will bloom in the first year from June through September. The stalks are covered in semidouble to double flowers. The series includes plants of varying heights, so choose carefully. My favorite is ‘Morning Lights’ (pictured), whose color looks like a layering of watercolor shades of blue and pink.

4. ‘Comtesse De Bouchaud’ Clematis

Name: Clematis ‘Comtesse de Bouchaud’

Zones: 4 to 9

Size: 6 to 10 feet tall and 3 feet wide

Conditions: Full sun to partial shade; fertile, well-drained soil amended with organic matter

“Floriferous” is the perfect descriptor for ‘Comtesse de Bouchaud’ clematis. From June until September, it is covered with large 4- to 6-inch-diameter blooms. An early-spring pruning combined with a generous topdressing of mulch will be the extent of your maintenance, and the rewards are tremendous. This clematis is happy trained up a wall, fence, or tuteur, or when allowed to sprawl on a shrub. Its one flaw is that it has a bit of lower-leaf drop, but an underplanting of a perennial with shallow non­invasive roots can cover its legs.

Photos: (1), Bill Johnson; (2), Jerry Pavia; (3), courtesy of perennialresource.com; (4), doreenwynja.com