Long Blooming Perennials
If you've read my book on making a perennial garden bloom all summer, you understand that squeezing an extra week or two out of plants begins with plant selection.
While there are other tricks to making the garden bloom all summer, good long blooming perennials plant selection is important.
Almost equally important is understanding that every garden and every garden year is different when it comes to long blooming perennials. Some of these plants will do much better in dry years (Achillea) than in wet.
Some will thrive in cold years (Campanula) while they will languish and rot in damp and humid conditions.
Always Different
With a big grin on my face, I will tell you that this is the joy and the challenge in perennial gardening. No two years are the same so you’ll never be bored with these long blooming perennials. No two years are the same so you’ll always be frustrated because THAT plant looked better last year or doesn’t look like the magazine picture or… Well, you pick the reason.
Also understand that when it comes to long blooming perennials, there is a world of difference between varieties of the same plant species.
The perfect example is in Hemerocallis or Daylilies. The old varieties typically bloomed for 21 days, producing a new flower every day. You got to watch the old blossoms fade after one day and you know the show was only a three week deal. Then the breeders introduced ‘Stella D’ Oro’ – the first commercially available repeat blooming daylily. We can now have several flushes of blooms of this plant and the breeders have been introducing varieties that outbloom old Stella who is now considered a historic plant in terms of introductions but is still the most popular daylily sold today.
I have Stella in my own garden but she is surrounded by heavier blooming and longer blooming (and fragrant) introductions. I keep her for old time’s sake but her days in my garden are numbered I fear.
And I haven’t included plants that don’t impress me with their blooms. For example, it is true that Heuchera bloom for a long time but I haven’t seen one yet that I’d get excited about. Now, the foliage on Heuchera is spectacular but this list is about long blooms, not great foliage.
Blooms Longer Than Three Weeks
Let us assume the average perennial flower is going to bloom for three weeks (some a little higher, some a little lower) so anything that exceeds this by a goodly margin is eligible to make this list.
Achillea is a long blooming plant for full hot sun
Agastache ‘Blue Fortune’ or licorice plant is one of the better longer blooming Agastache.
Anthemis tinctoria is a long blooming daisy that will self sow with abandon.
Asters; there are a few fall blooming asters such as ‘Monch’ and ‘Wonder of Staffa’ that are extremely long blooming. Check out the newer varieties.
Campanula a decent long bloomer three years out of four.
Centaurea montana was a reliable plant for me but self seeded everywhere.
Centranthus is easy and a little known but decent blooming plant.
Chrysanthemum. Everybody knows Shasta daisies and Fall mums. Deadhead the Shasta daisies for longer blooming.
Coreopsis. All bloom for extended times but the lanceolata and grandiflora types benefit from deadheading to get repeat blooms. Deadheading is not necessary with verticillata and rosea hybrids to make them into long blooming perennials.
Corydalis lutea is my favourite long blooming perennial and simply the longest blooming plant in my garden.
Dianthus can be very long blooming perennials if you pick new hybrids. Dianthus gratianopolitanus and D. deltoides are two of the best.
Dicentra Formosa and D. exemia hybrids are long lived for shade. Short bleeding hearts are superb while the taller ones are short bloomers. ‘Luxuriant’ has been my shade garden stalwart.
Echinacea are the current darlings of the plant breeding world and it is true the blooms last a long time and each individual flower lasts a long time. Good for mid summer blooms and so far they all seem to be about the same length of time in my garden.
Gaillardia are long bloomers but tend to be short lived. Will self sow but what a bloom they give.
Gaura plants are tremendous long blooming perennials and with its airy butterfly like flowers, it is a garden ornament worthy of the best designers. Grow it.
Geranium ‘Rozanne’ is a season-ling blooming geranium and the others are so-so long season bloomers. Watch for more repeat bloomers such as ‘Jolly Bee’ with its huge two-inch blue flowers. Both are stunning long blooming perennials in my garden (I like geraniums.)
Hemerocallis or daylilies ‘Stella D’ Oro’ is the classic but look for “repeat bloomers” at your favourite garden shop. See note in the introduction.
Heucherella – this cross between Heuchera and Tiarella has produced some very long blooming plants with dainty flowers. Not for heavy competition in the main flower border against phlox and daylily but lovely in containers or small dainty gardens.
Hibiscus moscheutos or perennial hibiscus is a very long blooming fall plant and the modern hybrids are simply stunning. I have three and I lust for more.
Kalimeris pinnatitida "Hortensis" or Japanese Asters produce a profusion of small flowers or a very long period of time.
Kniphofia can be long bloomers if you can grow them. The used to be very short green plants in my old garden. Haven’t gotten around to killing any in the new one yet.
Lavender is a classic long blooming plant for growing anywhere in the full sun.
Liatris, is Gayfeather or Blazing Star and is a good long bloomer and unusual flower heads.
Linum perenne or perennial flax is disappearing from garden centres because the larger nurseries have a hard time growing it. It produces literally hundreds of blue flowers every day almost all summer from early July onwards. Grow it yourself from seed – direct sow it in the garden – it is easy.
Lysimachia clethroides or goose neck flower. This blooms for a very long time but then again, after a few years of growing it you’ll have a tremendous number of this very aggressive thug in your garden.
Malva sylvestris or ornamental mallow blooms for a long time but is very weedy.
Nepeta or Ornamental Catnip is a good plant if you get the newer hybrids. The old species plants are not as long blooming.
Perovskia or Russian Sage gives a good blue mist to the garden in late summer and early fall and is a good plant in full sun gardens with great drainage.
The Backbone Plant
Phlox paniculata or garden phlox. No list would be complete without this classic backbone plant. Pick modern mildew resistant hybrids so the plant will keep its foliage on until August.
Rudbeckia or black eyed Susan is a good long bloomer. ‘Goldsturm’ is the classic standard and well worth growing. Pooh-poohed currently by the gardening “elite”, because it is over-used and “boring”. It is overused because it is rock hardy and long blooming. Go figure.
Scabiosa, the pin cushion flower, is a very long bloomer if you can keep the powdery mildew away from it. If you can’t, it’s a really short lifespan never mind bloom. The shorter versions have more flowers but also more mildew. Take your chance, if your garden is good for them, you’ll see blue and pink flowers for a very long time.
Sedums are very long blooming perennials in the fall garden and I can’t imagine a fall garden without them. Great new variegated varieties mean you don’t have to depend on flowers but the leaves give you season-long appeal. Again, newer varieties have different coloured foliages as well as good flower times.
Tradescantia is a mainstay of the damp garden where it will happily bloom almost all summer. Don’t let it dry out or it will immediately stop producing buds. One of the best long blooming perennials.
Veronicas are often suggested as good long blooming perennials and ‘Sunny Border Blue’ did very well for me. If your garden gets powdery mildew, this is another plant you should pass on.
This is by no means an exhaustive list of long blooming perennials. It is a good list for starting out and using these plants as backbone plants to ensure your garden has an ongoing supply of flowers.
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