While creating my last A Vine of Ideas digest, I wanted to share a decent list of the best perennials to grow in sun. But the lists I found were lacking. They were too long, not broad enough in terms of zonal hardiness, included fussy or hard-to-find plants, or listed actual shrubs. So I’ve compiled my own list of what I believe are the best low-maintenance, long-blooming winners. They’re all pretty and tough and widely available. Plus, they all attract butterflies, bees, and birds!
Daylilies (Hemerocallis) have got to be the easiest perennial to grow. They’re hardy to zone 3 and require little, if any, care. As they store energy in little tubers, they leaf out in early spring and bloom for several weeks in summer. Each blossom lasts for about a day, hence the name. I have the classic orange daylilies (hemerocallis fulva) that are larger, to about two feet high. With their arching spear-like leaves, they make quite a bold statement and fill in blank spaces rapidly. I also grow a dwarf ‘Happy Returns’ daylily, which is yellow and so darn cute. They don’t spread as rapidly, just simply hangout in their little space.
Salvias are known to be tender in northern gardens but I’ve denied my zone and grown ‘Black and Bloom,’ ‘Hot Lips,’ and other fun cultivars without returning success. I’ve also planted hardier cultivars and ‘May Night’ (salvia x sylvestris ‘May Night’) is my favorite. It’s got deep purple flowers that make a bold statement, especially paired with an orange rose or magenta peony. And they bloom for most of the summer with some deadheading. Plus, foliage leafs out early! ‘May Night’ also has excellent hardiness to zone 4. I think it’s a must-have for the garden. Plus, bees adore it!
The tall sword-like leaves of crocosmia (crocosmia) elegantly add contrasting structure to the garden. That they bloom in this succession of strongly colored, exotic-looking flowers is even better. I grow a couple different kinds and rarely think twice about them. If you like red, choose the taller ‘Lucifer.’ My favorite is ‘Emily McKenzie,’ which is shorter and brightly orange. Overall, as long as a crocosmia is in full sun and doesn’t dry out too much, they will produce late-summer blooms for many weeks. Delicate looking but super tough. Hardy down to zone 5.
You might know stonecrop (sedum spectabile) by its broccoli-like appearance. It emerges in rosettes before growing into 1-1 1/2 foot wide stalks topped with flat flower heads. Stonecrop is hardy down to zone 4 and loves to bake in the sun in poor soil. In late summer, red flowers emerge that then fade to marroon and darken to brown. In winter, their sturdy forms offer great structure and seeds for birds. ‘Autumn Joy’ is a reliable cultivar, but I also love the variegated ‘Autumn Charm.’ I also grow ‘Xenox’ and ‘Purple Emperor’. ‘Brilliant’ is a brighter version of ‘Autumn Joy.’ All are highly drought tolerant. A great perennial for sun.
When I think of tickseed (coreopsis grandiflora), I think of sunshine. These clumps of mostly yellow flowers (sometimes orange, red or bi-colored) bloom all summer long. They grow to about a foot high and require little care. I occasionally deadhead to prolong blooms. I grow the straight species as I like solid, darker yellows. A cultivar called ‘Main Street’ allures with its red-magenta color and the threadleaf plants add interest with narrow foliage. Some are hardy down to zone 4.
The phlox (phlox paniculata) perennial is an old fashioned mainstay and even though it’s dismissed for that, I still think it’s a great perennial to grow for constant summer color. And there are hundreds of colors to choose from! I have a cultivar called ‘Coral Red Flame’ that blares and a couple others whose names I can’t remember. ‘Ruby’ is a common cultivar with bright red flowers. These lovely perennials are not that drought tolerant, they like a bit of water in summer and even some shade. I grow mine in full sun with supplemental water and they do well, nestled in the mid-border due to the vertical form. I have had some powdery mildew problems here and there. Hardy to zone 3.
In my northwest climate, coneflowers (echinacea purpurea) take a while to get going in early summer, but once they take off, they bloom well into fall. These prairie flowers like well-draining soil but reward with some drought tolerance and rich friendly pink and orange colors. I grow some harder-to-find cultivars like ‘Tiki Torch’ and ‘Wild Berry,’ but the straight species is a fine choice for anyone with a garden between zones 3 and 8. The pink varieties look stunning beside the dark salvia ‘May Night.’
I fell out of love with irises for a while because they bloom during a shorter window in spring but if you’re looking for a low maintenance perennial, irises are a solid choice. They make up a broad family of Siberian, Japanese, and bearded varieties, which can be overwhelming. For regularly blooming color, I’d choose a Japanese or Siberian. In the northwest, I also grow bearded irises. Their flat wide leaves offer great evergreen structure. My favorite is Iris pallida ‘Aureo-variegata,’ which I like more for the striped yellow-green foliage than the lavender flowers. Hardy to zone 4.
9. Black-eyed Susan
Black-eyed Susan (rudbeckia fulgida) is another workhorse. You can plant a pot of these, turn away, and the next thing you know they’ve spread to form a pleasantly large clump. These two-foot perennials bloom from mid-summer to late fall, usually only fading just as the first frost arrives. Butterflies love the prairie flowers whose beaming yellow cheer up any garden. I grow ‘Goldsturm,’ which is the classic flower you often see in public and home gardens. In winter, I leave the dried heads undisturbed to feed the birds. Hardy to zone 4.
10. Bee Balm
Bee balm (monarda) almost didn’t make my list because it tends to get powdery mildew in fall but the flowers are so uniquely cool I just had to include it. They look like fancy crowns with points all around. Plus, hummingbirds and bees love them. Bee balm is a tough perennial, multiplying quickly and offering a punch of magenta or purple in a mixed border. I grow the larger ‘Raspberry Wine,’ a mildew-resistant cultivar, beside my purple smokebush. There are many dwarfs and colors available. Hardy to zone 3.
Runners Up: Peruvian Lily and Lavender
Peruvian lily (alstroemeria) is another beloved favorite of mine. I’ve had a peach cultivar whose name I don’t know (above), if it has one, for decades and every year I can’t wait for it to bloom. Usually, these back-of-the-border plants grow to almost three feet tall and depending on what’s around them, may need staking. Still, the cut flowers last a long time and they bloom profusely all summer without attention. I also have a ruby colored variety, which contrasts nicely with my Salvia ‘May Night.’
I didn’t include lavender in the main list because technically it’s a shrub. Still, English lavender (lavandula angustifolia) delights with silvery wands and fragrant purple flowerheads. Gardeners in colder climates can’t grow the more tender Spanish lavenders but English lavenders grow just fine down to zone 5. I’ve found lavenders look lovely lining a hot walkway and do best when trimmed after blooming, though be careful. A lavender can die if old wood is pruned. It’s fun to run your hands along lavender and enjoy the lovely scent!