Alpine plants Perennials

The Longest Blooming Perennial of All?

Abundant whitish flowers over deeply cut leaves of white corydalis

White corydalis: the perennial that won’t stop blooming. Photo: Michel Descamps, Sysbio

The older I become, the more I appreciate plants that cover the entire blooming season. Yes, I have grown and still grow lots of plants with a 2- or 3-week blooming period and enjoy trying to mix and match them with others with different blooming cycles so my garden is always in full flower right through the growing season. However, you simply can’t beat a plant that blooms for 2, 3 or 4 months or more to help give your garden a solid base of continuous color. But there aren’t many plants out there that really bloom from spring through fall. 

A Daphne × transatlantica shrub covered in white flowers.
Daphne × transatlantica (here the cultivar ‘Blafra’ Eternal Fragrance) is the longest blooming shrub I know, but white corydalis still beats it hands down. Photo: WBLA_Corky. Flickr

Of course, there are annuals, most of which have an incredibly long blooming period, but they’re not in bloom in the spring and, worse yet, you have to replace them yearly. I still do plant many kinds of annuals, but I prefer more permanent plants. There are no everblooming bulbs or trees (at least not for cold climates) and precious few shrubs, although Daphne × transatlantica comes awfully close (read more about this fantastic shrub in the article The Shrub That Just Won’t Stop Blooming), but it isn’t solidly hardy in my USDA zone 3/AgCan zone 4b garden. Plus, under ideal conditions, white corydalis blooms for an even longer time.

Among blooming plants, therefore, that leaves perennials.

Geranium  Rozanne blooms all summer and into fall with purple flowers.
Geranium ‘Gerwat’ Rozanne™is awfully long-blooming, but not as long-blooming as white corydalis. Photo: Geraniumplantlust.com

Now, if you ask most gardeners about everblooming perennials, they’ll mention gaillardias, coreopsis, a few geraniums (Geranium ‘Gerwat’ Rozanne™ is pretty incredible), some daylilies and maybe mauves and nepetas. All are great summer bloomers that continue well into fall, but … where is their spring bloom? Absent. One of the rare long-blooming spring-flowering perennials is Helleborus, but although it starts early enough, it’s all bloomed out by late June or early July. In fact, I’ve only found one family of plants that includes perennials blooming spring through fall, the Fumariaceae or bleeding-heart family. 

Dicentra ‘Luxuriant’ with blue green cut leaves and abundant pink flowers.
Some of the bleeding hearts, like this Dicentra ‘Luxuriant, are heavy spring bloomers, but peter out during the summer months, especially in hotter climates. Photo: gardengallery.ca

Better clones of the western bleeding heart (Dicentra formosa) and the fringed bleeding heart (D. eximia), plus hybrids between the two species (D. ‘Luxuriant’, D. ‘Adrian Bloom’, D. ‘Aurora’, etc.), are remarkably long-blooming, blooming massively in late May/early June then sporadically right through summer and early fall, at least in areas with cool summers, but you can’t trust them for summer bloom in hotter, drier climates.

 yellow corydalis with deeply cut blue-green leaves and yellow flowers.
Perhaps the second-longest blooming perennial is yellow corydalis (Pseudofumaria lutea). Photo: plantsam.com

Better yet is the yellow corydalis, Pseudofumaria lutea, formerly Corydalis lutea. It starts blooming a few weeks earlier than its relatives, the bleeding hearts, and continues just as long, into October. But even it is beaten by an even closer relative, white corydalis. 

And the Winner Is…

The finely cut leaves and the many flowers cive white corydalis extra elegance.
White corydalis (Pseudofumaria alba) will bloom pretty much all the time in a cool, yet snow-free climate. Photo: Andrea Moro, Wikimedia Commons

White corydalis or pale corydalis (Pseudofumaria alba, formerly Corydalis ochroleuca and Fumaria alba) is up and blooming by early May in my climate (it starts as early as February in its native southern Europe!), flowering along with the mid-season daffodils and tulips, and sails through the summer into October without stopping. November can be an iffy month where I live, with freezing nights and the first snows, but it keeps blooming right through them: the blooms don’t even seem to be damaged after a day or two under 10 cm of snow! What does stop it is when either the ground freezes solid or a long-lasting snow, one that will last until spring, settles in. Lasting snow usually arrives in mid to late November in my climate, but there are years when it comes late and the plant is still blooming in December. I’ve been told that it will bloom 12 months a year in climates where winters never include more than moderate frosts. Now that’s a long-blooming plant!

Keep It Cool

That said, white corydalis is not a good choice for climates where summer heat is a problem. Originally from mountain forest in southeastern Europe, it likes things reasonably cool at all times. It’s much hardier than usually claimed (I keep seeing USDA hardiness zone 5/AgCan zone 6 in references, yet it positively thrives in USDA zone 3/AgCan zone 4). It’s less likely to do well in the upper zones, beyond zone 8, where summers are torrid. Dry heat can even push it into summer dormancy.

The leaves are semi-persistant. They hang on into winter in my very cold climate, but are gone by spring, melting back to basically nothing. In milder climates, though, the leaves are present all year long.

Pretty as a Penny

Close-up of white cordyalis flowers.
Although the flowers appear creamy white from afar, up close, they’re white and yellow with distinct green markings. Photo: srgc.org.uk

Long-blooming and attractive too. Not a showstopper (the flowers are too small and their clusters too thinly spread for that), but pretty at all times. The blooms are borne densely on short spikes raised just above the foliage and appear creamy white from a distance. Up close you can see their unusual shape: generally tubular, but opening into lips with some yellow peaking out at the tip, while there is a green spot on the outside and a rounded white spur at the back. As one spike fades, others take its place and this continues until the ground freezes solid or the snow settles in.

Deeply cut foliage of white corydalis
The foliage is deeply cut and very attractive. Photo: Ewen Cameron, Wikimedia Commons

The foliage is attractive too: finely cut, fernlike and gray-green, perfectly setting off the flowers.

The plant is small to moderate in size, about 15 to 45 cm in height and about the same width. 

Good Care Means No Care

And did I mention it is easy to grow? Sun or shade seems to work equally well, as long as the plant gets some spring sun, and any soil will do as long as it is well drained, even alkaline soils. It positively thrives in dry shade where so few plants do well. I’ve been told it can go summer dormant in hot, dry climates when planted in full sun: if that describes your summer conditions, plant it in shade. Elsewhere full sun is fine. It requires no pruning, deadheading, staking nor any other meticulous care, nor does it seem to have any insect or disease problems and deer, rabbits and other mammals pay no attention to it. Just plant it and let it do its thing … which includes self-sowing.

Naturalized white corydalis mixing in with other plants, white flowers.
White corydalis self-sows modestly, naturalizing in open spaces in your landscape. Photo: dryades.units.it

Yes, it does get around. It’s not one of those invasive plants that crushes its neighbors, but rather pops up here and there, filling in open spaces. If you like formal plantings where every plant remains in its designated spot, simply don’t plant white corydalis: it is just not that kind of plant. It is, however, a plant you’ll adore if you like English-style mixed beds or naturalized woodland gardens.

White corydalis loves to sow itself into rock walls.
White corydalis seems to love rocks and will self-sow into the slightest crack of a rock wall. Photo: specialplants.net

It also likes rocks and has sown itself into a few retaining walls at my place. And thank goodness for that! Planting in rock walls is such a pain that I love plants that do it on their own.

And you do want the plant to self-sow, as it is not long-lived. I’ve been told that individual plants rarely live more than 2 or 3 years … but I’ve never had to notice, as there are always enough replacements in about the same spots that the death of a specimen or two doesn’t show. And it can only be propagated by seeds … fresh seeds. The best way to share plants with a friend is therefore to pot up any stray babies. 

Now the real downside: white corydalis is hard to find in nurseries. But do ask. You’ll be surprised at how many have it in their display gardens but have never bothered to pot it up. Or try ordering seeds by mail. Jelitto Perennial Seeds is one company that carries it.

So there you go: simply the bloomingest perennial ever and so easy to grow. Try it and see!

Larry Hodgson is one of Canada’s best-known garden communicators. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He has written for many garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 60 other titles in English and French. He is a past president of the Garden Writers Association (now Garden Communicators International) and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. He resides in Quebec City, Quebec, Canada.

2 comments on “The Longest Blooming Perennial of All?

  1. Christine Lemieux

    I am going to look for this little beauty!

  2. Beautiful flowers to bring some color into the waning winter.

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