Bulbs Gardening Laidback Gardener Tip of the Day

Forgotten Spring Bulb Creates Waves

Waves of corydalis unfurl presently in my shade garden.

Some plants just don’t get no respect. And that’s certainly the case with Corydalis solida.

It’s a small spring-flowering bulb that goes under the inauspicious name of fumewort, a name that practically makes me gag. Any gardener worth their salt simply calls it corydalis (pronounce it any way you want) or, if they’re trying to be specific (there are some 300 other species of Corydalis), bulbous corydalis. Of course, most gardeners have never heard of this bulb: it’s that rare.

But it really makes waves in the garden… waves of color, that is. The photo above was taken in my garden yesterday, where it blooms densely under the shade of tall spruces… a spot where little else wants to grow. How many bulbs do you think I planted to get that effect? 300? 500? 700? Try 3. Yes, all those flowers in all those colors came from just 3 bulbs planted 9 years ago.

I originally planted all 3 of the available bulbous corydalis varieties offered in Fraser’s Thimble Farms’ catalogue at the time. ‘Penza Strain’ (mixed purple shades), ‘Beth Evans’ (bright pink) and ‘George Baker’ (pink going on red). They’ve since self-sowed like the dickens and intercrossed too, I believe, as there are colors now I never had originally.

You might think I’d be upset by this massive proliferation… but I’m thrilled. After all, these are spring ephemerals, small plants that come up, bloom and grow dormant in short order. They do no harm to any established plants, most of which are dormant and out of sight at this time of year (remember, my garden has only come out of the snow within the last 10 days. There isn’t a leaf on a tree here yet and most perennials are totally invisible). By the time the hostas and ferns that dominate this space in summer have leafed out to any degree, they will have faded away completely. I don’t want less of them, I want more!

A Description

Bulbous corydalis belongs to the genus Corydalis and is closely related to the much better known bleeding hearts (Dicentra spp). There are other corydalis species you might know and grow, most of which are long-blooming perennials, not early spring bulbs, such as yellow corydalis (C. lutea), pale corydalis (C. ochroleuca), both of which have, by the way, been moved to the new genus Pseudofumara, and the different blue corydalis, like C. elata. There are other bulbous corydalis, some of which I also grow, but bulbous corydalis is the easiest to find and the most prolific.

The flowers are quite intriguingly shaped when you look at them up close.

It’s a small plant about 6 to 8 inches (15 to 20 cm) tall and wide that grows from an underground tuber. The gray-green leaves have a certain resemblance, by their texture and their form, to columbine leaves (Aquilegia spp.), but are more deeply cut. The flowers are borne on upright, somewhat arching stems of up to 20 flowers, each with a long upright spur, bending a bit towards the back, that opens into a flattened two-lipped “mouth” at the base. The flowers come in different shades of purple, pink, red and white. Bumblebees seem to love them!

How to Grow It

There’s quite a range of colors.

Bulbous corydalis is native to forests throughout much of central and northern Europe and Asia, from Sweden to Siberia and that is quite telling, for it does best in the shade (ideally under deciduous trees, as they let in plenty of spring sun) and are very hardy. Not that the latter bit of information seems to be getting around. I keep seeing it labeled as a zone 5 or 6 plant, yet it positively thrives in my zone 4 garden and I know people who’ve grown it for years in zone 3.

Plant the tuber about 5 to 10 cm deep in the fall. Plants can also be moved carefully in the spring while they are in bloom or leaf. Any well-drained soil suits it perfectly (it can withstand soils that are sopping wet in spring, as long as they dry out a bit in summer), but it does best in a soil rich in organic matter. If necessary, reproduce the abundant forest litter found in its native environment by applying a thick mulch. I mean, right over top of the tubers! Don’t worry: come spring, it will simply pop right throw.

Yes, in the wild, it’s a shade plant, but it will also grow in full sun, especially in cool climates. My neighbor now has a few sprouting in his sunny lawn thanks to me.

All my plants come from just 3 original bulbs.

If you read this text from the beginning, you probably already guessed that bulbous corydalis self-sows. Abundantly. If you want to start a new colony, simply move one of the self-sowers. You can also harvest and sow the seeds, but that’s a bit complicated. The capsule remains green when it is mature and will quickly split open and spread its seeds around before you even notice. So try to harvest them just before the capsule is fully ripe. Sow the seeds immediately, directly outdoors where they are to grow, as they are not viable for very long.

Other Varieties

Bulbous corydalis, and also its look-alike cousin, hollow corydalis (C. cava), come in a wide range of colors (purples, lavenders, pinks, reds and whites), but most color forms are hard to find. The varieties mentioned at the beginning of the article remain the most common ones. I must add I would love to find a white one to add to the mix, but haven’t been able to find one I can buy in Canada.

Where to Find One?

Every time I write about a plant, I get messages from people who want to know where to find it locally… as if I could ever know such a thing! (How would I know what is sold in your neighborhood?) Personally, I buy three quarters of my plants by mail order, following an old family tradition. And if you want to try bulbous corydalis, you’ll pretty much have to do the same.

It’s hard to understand why such a pretty, easy-to-grow plant is so rarely available. You’d think all bulb sellers would offer it.

You see, it just isn’t amenable to garden center sales. Unlike many other bulbs, like tulips, narcissus and crocus, that don’t mind sitting around for months on store shelves in bags or boxes, corydalis bulbs suffer greatly when they’re left to dry too long. You really should buy freshly dug bulbs in late summer or early fall and plant them without too much delay, that is, within a few weeks or so. That works fine with mail order: the seller digs and packs them at one end of the chain, then mails it to you so you can plant it quickly.

I ordered my bulbs from Fraser’s Thimble Farms, which ships to Canada and the USA… and they still offer them. Even then, you still have to wait. This nursery will only take orders for fall bulbs starting in July. Arrowhead Alpines and Brent and Beckys’ Bulbs are other US sources you could try.

As for European readers, I strongly suggest that you buy your bulbs from Rare Bulb Nursey, the world’s biggest small bulb specialist. You’ll find an incredible list of different cultivars in every color imaginable. I only wish there was that much choice in North America!

If you’re a laidback shade gardener, you’re really going to love this bulb’s ability to carpet your shade garden all on its own: try it and see!20170512A

1 comment on “Forgotten Spring Bulb Creates Waves

  1. Yvette Sneath

    VERY enlightening. I have Fraser’s Thimble Farms catalogue open in Chrome while I use another browser to search images and cultural information about some of the listings from Fraser’s. I’ve never planted Corydalis (indeed I never knew it was so hardy!) but thanks to you, I’ll definitely try them.

    Yvette Sneath, St. Catharines, Ontario

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