Vision in Blue
Full sun to partial shade
Average soil
Blue flowers never fail to please, so when you plan an entire garden around them, you have a plan for success. From intense cobalt blue to palest sky blue, from icy silver blues to sumptuous purple-blues — your options for beautiful blue blooms are seemingly endless. Even some leaves get into the act, in cool powdery blues that keep the color theme going when the flowers take a break.
The Garden Plan
Shopping List
1 Arkansas bluestar
Amsonia hubrichtii
2 plants
Zones 4–9
Alternates: Another 2- to 3-foot-tall and -wide perennial with blue or purple-blue flowers, such as ‘October Skies’ aromatic aster (Aster oblongifolius) [2 plants] or blue false indigo (Baptisia australis) [2 plants]
Arkansas bluestar (Amsonia hubrichtii)
2 ‘Blue Fortune’ hyssop
Agastache
2 plants
Zones 5–9
Alternates: Another 3- to 5-foot-tall perennial or shrub with spiky blue or purple-blue flowers, such as Russian sage (Perovskia atriplicifolia) [2 plants] or Adonis Blue (‘Adokeep’) or ‘Blue Chip’ butterfly bush (Buddleia) [2 plants]
‘Blue Fortune’ hyssop (Agastache)
3 ‘Heavy Metal’ switch grass
Panicum virgatum
3 plants
Zones 4–9
Alternates: A 3- to 4-foot-tall, blue- or purple-blue flowered perennial, such as a Siberian iris (Iris sibirica) [2 plants], globe thistle (Echinops ritro), or a blue mist shrub (Caryopteris × clandonensis)
‘Heavy Metal’ switch grass (Panicum virgatum)
4 ‘Caradonna’ ornamental sage
Salvia
5 plants
Zones 4–8
Alternates: Another blue-flowered perennial sage, such as ‘May Night’, or another 18- to 30-inch-tall perennial with blue or purple-blue flowers, such as ‘Sapphire Blue’ sea holly (Eryngium) [5 plants], blue lobelia (Lobelia siphilitica) [5 plants], or ‘Grosso’ or ‘Provence’ lavender (Lavandula × intermedia) [5 plants]
‘Caradonna’ ornamental sage (Salvia )
5 Rozanne geranium
Rozanne geranium (Geranium ‘Gerwat’)
Geranium ‘Gerwat’
5 plants
Zones 5–8
Alternates: Another 6- to 18-inch-tall perennial with blue or purple-blue flowers, such as catmint (Nepeta × faassenii) [5 plants] or leadwort (Ceratostigma plumbaginoides) [9 plants]
Planting Plan
Season by Season
Spring: Leafy growth starts sprouting in early to mid spring on most of these perennials, though the gray-blue new shoots of ‘Heavy Metal’ switch grass usually rise a bit later, in mid to late spring. By late spring, the clustered, pale blue flowers of Arkansas bluestar are in full bloom, and the deep purple-blue spikes of ‘Caradonna’ ornamental sage may be opening, too.
To get your blue garden off to a great start for the growing season, cut down all the remaining dead stems and leaves in early spring. This is also a good time to divide the hyssop, switch grass, ornamental sage, and geranium if they were starting to crowd out their companions by last fall. Finish up by applying a fresh layer of organic mulch around the plants.
Summer: Arkansas bluestar finishes flowering in early summer, but the ‘Caradonna’ ornamental sage is in full glory well into summer. The purple-blue spikes of ‘Blue Fortune’ hyssop and bowl-shaped blooms of Rozanne geranium join in now, too, and contribute color for much, if not all, of the summer. You also get the gray-blue leaves of the ‘Heavy Metal’ switch grass all summer. (‘Heavy Metal’ flowers, as well, with loose, reddish green plumes in mid to late summer, which are pretty even though they don’t add much to the blue theme.)
Once the Arkansas bluestar is done flowering, cut it back by one-third to one-half of its height to remove the developing seedpods and encourage lower, bushier regrowth. Trim the ornamental sage back by about one-third in mid to late summer and the hyssop back by about one-quarter in late summer to promote rebloom later in the season. If the geranium stops flowering or looks straggly by late summer, snip off all of its trailing stems close to the center of the plant, where new growth will quickly sprout if it hasn’t already. Water the garden during summer dry spells.
Fall and Winter: The blues keep coming into fall, with more flowers from the ‘Blue Fortune’ hyssop, ‘Caradonna’ ornamental sage, and Rozanne geranium from early fall to frost. Cooler weather brings out some other colors, too: the leaves of Arkansas bluestar usually turn bright yellow, as do the leaf blades of ‘Heavy Metal’ switch grass, and the foliage of Rozanne geranium often turns showy shades of orange and red.
In mid to late fall, cut down the freeze-killed tops of the Arkansas bluestar, switch grass, and geranium and clip off the finished flower stems of the ornamental sage back to the ground-level leaves, if you wish, or leave all of the tops in place for winter interest. (Even if you cut down the other perennials, it’s a good idea to leave the hyssop stems alone until spring cleanup, to improve the odds of the plants surviving the winter.)
Digging Deeper
- This blue garden would show off beautifully against a light-colored background, such as a white or pale gray house wall or fence. Try it as a foundation planting along the front of your home, as a multiseason border next to a deck or patio, or as an edging along a driveway or sidewalk. If you need to fill a longer space, repeat the plan end to end, mixing in some of the suggested alternate plants to add some variety.
- Blue flowers tend to fade into the background, so keep them for areas where you’ll see them at close range: by your front door, for instance, or around your favorite summer sitting area. Complement their soft colors by pairing them with gray and blue leaves, or give them a bit of zip by combining them with white and yellow flowers or white-striped, yellow-striped, or bright silver foliage.
- As you can guess from their common name, bluestars (Amsonia) are obvious choices for blue gardens. The starry flowers are light blue to near white on Arkansas bluestar (A. hubrichtii) and eastern bluestar (A. tabernaemontana), both of which have an upright to vase-shaped form at their late-spring bloom time and a bushy, mounded shape from midsummer on. The hybrid ‘Blue Ice’ is a richer blue in flower and forms lower-growing clumps. After their bloom display, bluestars offer rich green leaves for summer interest and often turn showy shades of yellow in fall. These dependable, long-lived perennials also tend to be deer resistant — a big plus where these animal pests are a problem.