Ephemerals at superlative, spring Corydalis species emerge fast, flower abundently, set seeds and then quietly disappear in early summer. But for that brief time, they will fill your heart with unconditional love for the years to come. The ferny-looking foliage and long spurred, tube-shaped flowers are adorable providing the much needed burst of colors after our long winters; also, they are very precious food for early pollinators. They are not a good fit for very ‘tidy’ gardeners, but for all of us wild at heart, they are on the list of ‘plants we cannot live without’.
Every spring I look fwd to the first Corydalis solida (and others) to start poking through the ground. With the same excitement I await for the first bumblebees to arrive; the 2 events are tightly linked. 
A little while ago, someone wrote to me to happily announce that his Corydalis seeds have germinated; the message was also somehow showing disbelief to see the seeds germinating and I wondered why? I showed and wrote so many times how easy it is to grow them from freshly sowed or moist packed seeds.
As it turns out, I wrote small bits here and there but there is no post with a clear title: Growing Corydalis from seeds on the Germination page. So, here it is one where I tried to put together everything I have. When they are in flower and later, there is little time left for writing.
Other species I’ve personally grown from seeds beside Corydalis solida, are: Corydalis malkensis, Corydalis caucasica, Corydalis paczoskii, Corydalis bracteata, C. intermedia, C. kusnetzovii, C. ambigua…. Also, Corydalis nobilis it is easily grown using the same method and probably other Corydalis species from any temperate/cold climate.
To start from the beginning: you need to sow fresh seeds or seeds that have been kept moist.
The seeds are ready sometime in late May/June in our climate. The capsules easily split open when mature and eject the seeds, so if you want to catch the seeds is best to go around the garden every day to collect the seeds. Even if they reseed easily, if you want to actively increase your stock, it is still the best to collect the seeds; otherwise, the ants will carry them maybe to places where not all the seeds may be able to germinate (the seeds present elaiosomes which attract ants).
The exact moment requires some practice to observe. After a while you will learn to ‘see’ when the right moment arrives. Be wary of collecting them too early! In the majority of cases, the seeds are black and shiny at maturity. You can sow them right away, or keep them for short periods of time. For this, place them in a small paper bag or in coffee filters. Coffee filters work great for keeping freshly collected seeds and you can even fold them to make small packets!
For best results the seeds need to be sown fresh or kept in slightly moist vermiculite for later sowing. By fresh, I don’t mean sowing the next day. The seeds can withstand a few weeks dry; placing them in moist vermiculite right away will lead to rot.
The seeding habit of Corydalis in nature gives us information about their germination requirements: cycles of summer-fall-winter temperatures, in moist conditions (warm/cold).
Sow the seeds as usual, using a slightly ‘heavier’ sowing mix: for example combine a sowing mix with some garden soil. Regular sowing mix contains too much peat and dries out excessively. It is never good for seeds/seedlings that are meant to stay in pots for 2-3 years.
Also, because the seedlings will be grown in the same pot for 2-3 years, use slightly larger pots when sowing: 3,5 x 3,5 in or 4 x 4 in work well. The seedlings will not be pricked out.
Add a layer of small gravel/grit, water well and place the pots in a shaded area. If critters are a problem, covering them with a mesh is a great idea. Water once is a while throughout the season, especially during the dry spells. Don’t forget that the seeds are ‘alive’ in the pots.
For the winter, leave the pots outdoors under snow, a cold frame, or make a little special area for your sowings, which can be covered with a fleece and a tarp until spring.
Likewise, you can dig a small trench and ‘plant’ the pots in it. That’s what I did when I had a large Corydalis sowing collection a few years ago. The soil around the pots maintains the humidity more constant. It is like sowing seeds directly in the ground, but with a bit more control.
Freshly sown seeds will promptly germinate in the following spring, grow for a few months and then go dormant (you will notice the leaves yellowing from which point be careful not to over-water). Another season of ‘empty looking pots’ that need caring will follow.
My method is to grow them in the same pot for 2 years, and at the end of the second cycle, I plant the small tubers in the ground (sometime in July/August). In most cases, the first flowers will appear in the third year.
Of course, you can grow them in pots until flowering, if space is not a problem, although frankly I killed more ephemeral species in pots than when planted in the ground. It is much easier to let nature take care of them.
For those having no experience with sowing, I think the best is to sow the seeds directly in the ground (mix them in the top layer of soil), and let nature take its course. Like I explained with other occasions, when sowing directly in the garden, choose a location close to an establish large perennial, where you would water during dry spells (plus that you won’t disturb the little seedlings when dormant). Don’t scatter the seeds over a large area, you can move them after 2-3 years when they get bigger (you can do the same for Erythronium and Trillium species).
Corydalis solida cross-pollinate freely, which means that growing it from seeds, there is no guarantee you will obtain the same seedlings as the mother plants. The same is valid for a few other species. However, if you collect seeds from a population of the same color, then the chances of obtaining seedlings true to the mother-plant increase.
With this in mind, take it with a grain of salt when purchasing Corydalis tubers and proudly sticking the labels in the ground. The only way to have true to name cultivars is to propagate them vegetatively and that is not always the case.
On the positive side, cross pollination leads naturally to interesting forms; all one has to do is pay attention and select them.
How spring would look like without various Corydalis? I can’t imagine that. A short preview of the good things to come.
We are well prepared now; waiting for them to flower again and if possible, provide more seeds!
