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Long-Blooming Perennials

September 11, 2014

One of the challenges of gardening with perennials is that, unlike annuals, most do not have long periods of bloom. Some, like peonies, are notorious for a flash of glory which can end almost as soon as it begins when the blossoms shatter in the heat or are flattened by heavy rains. While most are longer-lasting than peonies, perennials are not generally known for providing color all season long. Some strategies for dealing with this characteristic of perennials include mixing perennials with annuals, designing gardens that focus more on foliage than on flowers, and mixing a variety of flowering perennials with a succession of bloom times.

Geraniums 2013

But a gardener who is in love with flowering perennials might also be interested in finding perennials with long bloom times. In my Maine garden, I consider perennials that will bloom for eight weeks or longer during the garden season as long-blooming. Achieving this is easy at the genus level. For example, I grow more than a dozen different species and hybrid varieties of hardy geranium, and one or more of these has been blooming in my garden since the first week in June.

fall fence border dayliliesHemerocallis (daylilies) is another genus that provides bloom in my garden for much of the season. This year, my first daylily to bloom was the reblooming variety ‘Happy Returns,’ which opened its first flower the last week in June. I have had daylilies in bloom somewhere in my garden continuously since then. Currently, there are three late-blooming varieties —  ‘Autumn Minaret,’ ‘Final Touch,’ and ‘Sandra Elizabeth’ — providing a beautiful display in the fence border. The very late daylily‘Sandra Elizabeth’ did not begin blooming until the first week in September.

09geranium & hosta_1But what about individual plants that bloom for eight weeks or longer? This is a greater challenge, but I do have a number of such plants in my garden. One of my long-blooming stars is Geranium x oxonianum; its lovely clear pink flowers first appeared in my deck border the second week in June, and are still blooming there more than 12 weeks later. Another plant of this hybrid in the circular bed bloomed for 12 weeks before going dormant, and new plantings in their first year in the raised bed bloomed for 10 weeks. Various cultivars of Tradescantia virginiana are also long-blooming in my garden. Particularly notable for its longevity is the variety ‘Osprey;’ one self-sown plant of ‘Osprey’ in my deck border has been blooming continuously for the past three months and still has a few unopened buds. Other long-blooming perennials include Astrantia major, which has been blooming in my serenity garden since the beginning of July, and varieties of Heuchera. Heuchera ‘Raspberry Regal’ bloomed continuously for 12 weeks, and one plant of H. ‘Raspberry Ice’ has been blooming in the deck border for the past three months and is likely to continue blooming until frost.

long-blooming perennials

Geranium, Tradescantia, Astrantia, and Heuchera are all plants with small flowers and prominent foliage. Their display in the garden is often a subtle one, especially since their big first flush of blooms is typically followed by sparser flowering. fall heliopsisThere are other long-blooming perennials in my garden, however, that put on a big showy display for eight weeks or more. Chief among these is the false sunflower (Heliopsis helianthoides), which begins blooming in mid-summer and often continues until frost. One clump of this plant blooming in the holding area, for example, began blooming during the second week in July (9 weeks ago) and are still going strong. Another big, showy plant that is often long-blooming is the tall Rudbeckia lacianata x ‘Herbstsonne’ (‘Autumn Sun’); this plant began blooming at the back of my blue and yellow border 6 weeks ago and is likely to continue until frost.

herbstsonne in blue&yellow

It’s not possible to create a list of reliably long-blooming perennials, because which perennials will have long bloom periods depends greatly on local climate and conditions. Many gardeners in warmer climates than mine swear by the hybrid Geranium x ‘Rozanne’ as a long-blooming champion, but this plant is not reliably winter-hardy in my zone 5a garden.  By contrast, some of the long-blooming perennials in my garden, especially Geranium x oxonianum and Tradescantia virginiana are not heat-tolerant. In warmer climates, these will bloom in late spring and then go dormant in the heat of summer, perhaps to bloom again in autumn. (This is how divisions of both these plants behaved in my zone 6b Gettysburg garden.) But in my cool Maine garden, these will often bloom continuously all summer long. Micro-climates within the garden also matter; several plants that I have growing in different parts of the garden seem to have longer bloom in cooler, slightly shadier locations. Rudbeckia ‘Herbstsonne,’ for example, blooms longer in the partial shade at the back of the blue and yellow border than it does in the sunny fence border, and Astrantia major has bloomed longer in the deeper shade of the serenity garden than in the light shade of the deck border.

It seems likely to me that, with some trial and error, most perennial gardeners can identify perennials that are long-blooming in their conditions. Which perennials have long bloom periods in your garden?

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28 Comments leave one →
  1. September 11, 2014 11:23 pm

    You’re right that climate plays a part. In my old garden, Geranium x cantabrigiense ‘Biokovo’ had a very long bloom cycle, as did G. x oxonianum ‘Katherine Adele’ but neither performs as well in my current hotter, drier garden. For long-term floral color, I rely more on shrubs like Cuphea x ignea ‘Starfire Pink,’ which blooms year-round until it’s hacked almost to the ground, Phlomis fruticosa, and some of the Grevilleas and Hebes. The re-blooming evergreen daylilies also offer repeated, if not continuous, displays.

    • September 16, 2014 7:21 pm

      Kris, ‘Biokovo’ is a flash-in-the-pan type of flower in my garden, puts on a big show, but lasts less than a month. I, too, find some shrubs to be good long-bloomers; Spirea japonica x ‘Magic Carpet’ provides long bloom in my garden.

  2. September 12, 2014 1:13 am

    Your garden photos are such a joy to look at…So full of color and an enthusiasm for life.

  3. September 12, 2014 7:14 am

    Hydrangea and Black Eyed Susans seem to bloom the longest for me. 🙂

    • September 16, 2014 7:22 pm

      Judy, I wish I had the right conditions for hydrangea, which I love. Alas, my one-step-removed-from-beach-sand soil is not a good environment for a water-loving plant.

  4. Nell Jean permalink
    September 12, 2014 11:52 am

    You are correct that ‘…which perennials will have long bloom periods depends greatly on local climate and conditions.’

    Many of my tender perennials are annuals in a cooler climate, like Pentas. Some of my root hardy perennials are shrubs that bloom year-round in a warmer climate than mine and in a warm winter may stay green here. Duranta for example died to the ground last winter but not the year before.

    Not only is each garden different, every year is different. Some of my reblooming Hemerocallis are sullen this year.

    Tradescantia virginiana is a weedy native here. The only Geranium we have is a late winter weed.

    • September 16, 2014 7:26 pm

      Nell Jean, The heat-loving plants that thrive in your garden would never make it in mine. I’ve gotten very little bloom out of my reblooming daylilies this year. Even ‘Happy Returns,’ which I normally think of as the energizer bunny of daylilies, only had 3 flowers on its second flush of blooms. In my case, the problem has been a summer much too short for rebloom. The daylilies began their first blooms a week or two later than normal, and frost is likely later this week.

  5. September 12, 2014 4:01 pm

    Interesting post, Jean. In my garden, my long bloomers are daylilies, perennial phlox, rudbeckia and coneflowers. For some reason, my longest blooming ones are also late bloomers. I think that is just a coincidence though. Cheers. And lovely photographs!

    • September 16, 2014 7:27 pm

      Diane, That’s an interesting observation that your longest blooming plants are also late bloomers. I’m wondering if it’s more than just a coincidence.

  6. September 12, 2014 5:16 pm

    each year is different. I always have something in flower, so I’m less concerned about one plant having a long season. Now the plum tree is veiled in white!

    • September 16, 2014 7:29 pm

      Diana, I can see that in a garden that blooms year-round (unimaginable here), how long any one plant blooms would be much less important.

  7. September 12, 2014 7:38 pm

    Jean, I find that rudbeckia ‘henry eilers’ is a long bloomer. I’ve never ‘clocked’ it, but it’s been blooming for weeks on end. I, like you, have a range daylilies that bloom for me from mid May til mid Sept.
    A charming annual that reseeds itself so freely and consistently that I almost think of it as perennial is the Chinese forget-me-not. Grows quite differently than the typical spring ones. About 2′ tall, airy stems, and I’ve had some blooming all summer and some still in bloom. Holler if you’d like some seeds and I’ll mail some so you can scatter them this fall.
    Still awaiting anxiously for an update on the addition.

    • September 12, 2014 7:40 pm

      PS – they would be so pretty in your blue & yellow garden!

      • September 16, 2014 7:41 pm

        Ginny, I had never heard of Chinese Forget-Me-Not and had to look it up. A re-seeding annual might be a great addition to my garden, and I certainly have “well drained soil.” I don’t think I’m ready to sow seed this fall, but I might take you up on this offer next year.
        The addition is proceeding, but slowly. I’m learning to double any time estimate made by a building contractor 😐 ! Maybe I’ll get my photo montage of the construction together by next week; I’ve been waiting for the outside to be mostly completed, which may happen in the next few days.

  8. September 13, 2014 10:06 am

    Jean I am finding geraniums blooming again with native Tradescantia still blooming…I find heliopsis still blooming and if the summer is not too dry monarda is long blooming with phlox.

    • September 16, 2014 7:43 pm

      Donna, I think some of my geraniums (like Brookside) would be blooming again if it weren’t so cold at night. The phlox are trying to make more flowers; we’ll see if they manage to open any of them. Frost is forecast for later this week!

  9. September 13, 2014 4:56 pm

    Here in my yard in Michigan I wish I could find a way to kill the hardy geraniums like the pink one in the bottom row of your first photo. They seed themselves all over the place, even in the neighbor’s grass three houses down. I have learned to transplant them down wind in the back field where the color is welcome, but I wish the person who gave this non-garderner that first plant would have told me how fast they multiply.

    • September 23, 2014 9:33 pm

      Jean, Beware of free plants from gardeners: they are usually plants that are pretty but that the gardener has plenty of to spare because they reproduce so readily. This year has been the first time any of my geraniums have self-seeded (yes, that pink one!), but I have sterile geraniums that spread like crazy by their roots and Tradescantia (spiderwort) that self-sow everywhere. I have even been guilty of giving these away to others — although I usually try to include a warning about their spreading tendencies. I always joke that if my investments multiplied as fast as my Geranium x cantabrigiense, I’d be wealthy and could have retired years ago!

  10. September 14, 2014 4:15 pm

    Hi Jean, I like to have plants that have a mix of flowering times, some that lazily flower over a whole season and some that have one big brief show. Spring flowering shrubs fall into the latter category. A long blooming perennial we have would be Abutilon Megapotamicum, it started flowering around late spring and is still going, months later. We also have a fuchsia that just about manages to survive the winter (with some protection) and that flowers quite heavily for months and will keep going until the first frosts hit it.

  11. September 14, 2014 10:54 pm

    Many of the plants that I sell bloom for eight weeks starting with hellebores and pulmonarias. Maybe that’s because as you mention they are shade plants. However, customers always want plants that bloom all season, spring into fall, they really want an annual. I recommend Rozanne as you said plus yellow corydalis and a cultivar of lamium called Shell Pink.

  12. September 15, 2014 10:42 am

    Thanks for the information on long blooming perennials. We live in a zone similar to yours and I am interested in those late blooming daylilies that you described. I have some of the re-blooming variety, but in this climate they do not reliably re-bloom. I loved your tall rudbecki and didn’t realize that it would perform that well in some shade. And I found that unless I plant the hardy geraniums in full sun they don’t flower very well for me. We do have a lot of shade in our gardens.

    • September 23, 2014 9:43 pm

      Sue, I have also been surprised that the tall rudbeckia ‘Herbstsonne’ performs better in some shade than it does in full sun. For some suggestions on finding late-blooming daylilies, see this earlier blog post on the subject. ‘Autumn Minaret’ and ‘Final Touch’ just opened their last flowers a couple of days ago, and ‘Sandra Elizabeth,’ which didn’t begin blooming until the first week in September, still has many buds remaining. (I threw a sheet over it on the one night we had some light frost to protect those buds.)

  13. September 22, 2014 1:21 pm

    Since starting to shy away from annuals a little the subject on perennials really interests me Jean. This year I planted (Heuchera Paris) The blooms are the most striking I have ever seen in Heuchera and each flower panicle goes on and on for two months and when you think its all over, equally strong flowers appear again which bloom beyond late Summer.

    • September 23, 2014 9:47 pm

      Alistair, Thanks for the tip about Heuchera ‘Paris.’ I just checked online for availability, and Plants Delights nursery lists it as the best-blooming Heuchera they’ve ever grown.

  14. September 26, 2014 8:00 pm

    In this last week of September, I have discovered a no-name and very tall pink variety of Phlox paniculata that still continues to bloom. What a pleasant surprise and how frustrating that I am unable to identify it.

    • September 26, 2014 8:22 pm

      Allan, I’ve also noticed some bright pink phlox blooming through September around my neighborhood. (One garden has it planted with cosmos, and the combination is enchanting.) I have a sense that these phlox are some old variety long since lost to commerce.

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