Pricking-transplanting seedlings

I recently got a question about pricking seedlings. It referred particularly to Aquilegia flabellata and Capnoides sempervirens started in early February, which are now starting to look a bit unhappy. Liz (not real name) did a very good job! and notice the coir fiber pot used for Capnoides (it can be planted as a whole in the ground).

This is a good occasion to talk about if, when and how to prick out seedlings in general.

So, you got your seedlings growing. What next?
Most will need to be prick out. Common saying is that this should be done after the true leaves are formed. Usually we are doing it much later.

It all depends on what species were sown, the size of pot used and germination percentage.
For species with very good germination rate, the sowing pot will get insufficient to sustain a good growing for all seedlings.
From my warm sowings of this year: Thymus zygioides, Paronychia cephalotes, Acinos alpinus…..they are all pricked out as of last week.

How to proceed? I will exemplify with pictures of Anthemis carpatica seedlings of last year.
First, let the mix to dry out; if the mix is too wet most fine roots will break when you try to separate them. The more roots you preserve, the better.
Gently squeeze the pot on all sides; the content should easily slide out (if too wet, wait a few more days).
Place the pot content on a tray, plastic sheet…then separate the seedlings. Ideally, the roots should easily come loose when trying to separate the seedlings.

It is quite amazing how many seedlings will come out from a 6 x 8 cm pot! Lower right corner – Silene suecica before pricking out last week.

Since we are not talking nursery production :) it is best to not prick out individual seedlings, especially for species with fine seedlings (discard the very week or the ones with broken roots). I usually make bunches of 2-3+ seedlings and repot them together in a pot with fresh potting mix. By transplanting in bunches you obtain a nice clump-like looking plant fast. Large seedlings are best potted only 1-2/pot (Centaurea, Eryngium, Helleborus….).

Various pricked out seedlings; choose the size of the pot accordingly with your needs: Oxyria dygina, Centaurea orientalis and Acinos alpinus

Water thoroughly.
Wait 1-2 days before placing the pots again under the lights (if outdoors – keep them out of direct sun for few days).

*Various Fabaceae may not react kindly at transplanting and it is best to do it fast before the roots grow too long. Same applies for the true alpine species, which grow up very long roots although the aerial growth seems small.

It is good to learn from mistakes, so I will show a Lupinus breweri seedling of last year: I waited too long for transplanting, that’s for sure! The plant survived but later slowly disappeared. Most Lupinus species are prone to do this and are best sown directly in the garden or pricked out very, very young.
The same goes for Astragalus, Oxytropis and other ‘legumes’.

 

What happens if you don’t transplant the seedlings?
In some cases, the young plants will stop growing because of lack of nutrients and space. Especially in small pots all potting mix is ‘consumed’ by the roots which will became entangled at the bottom. In most extreme case the seedlings may perish or get sick.

We can learn again from my mistake. Last year I failed to prick out all seedlings (again). In the plate below, I show 3 species I transplanted only in October. Notice the root system of Anemone caroliniana after growing in a small pot from May to October!. Being too late for the roots to have time to re-establish, I transplanted the Anemone and Clematis in larger pots without separating the seedlings.

!Various species seedlings do not need to be pricked out and react badly if you try to do so.
I already mentioned this for Arisaema species, Roscoea, most Liliums, Fritillaria spp., Podophyllum, most Iris; in general any rhizomatous/bulbous/tuberous species (Allium, Calochortus, Crocus, Gladiolus,….). They are all best grown in the same pot for 2+ years.

If you realize the sowing pot is too small to ensure good growth, the best option is to transplant the whole content in a larger pot. This can be done at any time during the growing season (Lilium philadelphicum 2 years old seedlings transplanted as a whole in a larger pot shown above).

Another option is to wait until the seedlings go dormant and repot the little bulbs/tubers in new pots, keeping the same depth where you found them. Problem is that in many cases they are tiny, and most likely some will be lost in the process (I’ve been there).

Good luck and keep growing!

 

 

Sowing advice for springtime

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With the first snowdrops in bloom spring is undeniably in the air. It is an exciting time with renewed hope and we all think about new plants to add in the garden.
Some people plan well ahead about what to grow from seeds, but others maybe purchase seeds and plants on the impulse of the moment. Then, there are always seeds arriving late from seeds exchanges.

Because all the latest orders had in common a combination of species, warm and cold germinators, I feel obliged to repeat how to proceed at this time in order to obtain the best results with minimum effort. Good timing for sowing is important!
If you don’t need advice, jump to the end of the post to see a few ‘green things’ from the garden :) All grown from seeds, except the snowdrops.

For those in the Northern Hemisphere
Species that are indicated to germinate at warm (15-20C) can be sown right away if you use indoor lighting for growing seedlings or later (April/early May) if you intend to keep the pots outdoor.

*Species indicated to have double dormancies and require first a slightly warm cycle, followed by a cold one in order to germinate (Hydrophyllum, Euonymus, Actaea…) – can be sowed later, in the summer. Most Peonies are also in this category; sowing in late June/July gives them more than enough time to develop the roots until late fall. Same goes for two stage warm germinating Lilium species (L. michiganense, L. monadelphum…).

Various Fabaceae can be treated with the ‘hot water treatment’ and considered warm germinators. Last year tests gave excellent results (Hedysarum, Oxytropis, Astragalus, Baptisia, Thermopsis, Lupinus*).

Species that can be sowed ‘in situ’ (Papaver, Lobelia, some Viola spp.…) – wait until April/early May and cast the seeds in place, incorporating lightly (most such seeds are fine and need light to germinate), keep the area moist and if there are too many critters around consider placing a mesh on top of the sowing location.

Species indicated as: sow in the fall or cold/moist stratification – I advise you to keep the seeds packets in the fridge until fall, and then proceed with sowing (in pots or ‘in situ’).

You can of course try to provide cold/moist stratification in the fridge, but don’t expect the same good results. Also, you may end up with seeds germinating in June/July and young seedlings by late fall withstanding poorly the winter cold.

 Moist packed seeds: not sold at this time of the year, with the exception of two years germinators (Caulophyllum, Medeola), when stock supply and temperatures allow.

Cypripedium: if not using ‘in vitro’ equipment, as discussed already, there is a slight chance that by incorporating the seeds in the garden close to where other orchids thrive, to be successful. Note the ‘slight chance’.

Those in the Southern Hemisphere: reverse the timings, sow the cold germinators, keep the warm ones in the fridge.

snowdrops

Draba lasiocarpa (warm germinator)

Erinus alpinus (warm)

Papaver atlanticum ‘Flore-Pleno’ (direct sowing)

Polygala vulgaris (cold)

Potentilla porphyrantha (warm)

Helleborus foetidus (moist, warm/cold)

Mitella diphylla (cold)

Aquilegia ecalcarata: use it or lose it syndrome

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Many articles have been published regarding the relationship between the intra/interspecific variation of floral organs and the primary pollinators, and not only for Aquilegia.
So, it seems a bit superfluous to repeat that the length of the nectary spurs in Aquilegia species is an adaptation that has evolved to match the feeding structures of their pollinators (bees, hummingbirds,…and not only). The spurs development is achieved purely through cell-shape anisotropy.

In the case of Aquilegia ecalcarata, the spurless columbine, according to various sources the main pollinators are syrphid flies (with short feeding structures). Not having spurs, doesn’t make it a ‘false’ aquilegia; it is just a classic example of “use it or lose it” evolutionary syndrome :+)

A few studies using ancestral character reconstruction of pollination  syndromes have shown  that  the  ancestor  of  the  genus was pollinated  by  bees/bumblebees (see notes).* Aquilegia ecalcarata it is the only species that has lost its spurs.


Aquilegia ecalcarata Maximowicz, was reconsidered for a while under the name/genus of Semiaquilegia ecalcarata (Maximowicz) Sprague & Hutchinson; S. ecalcarata f. semicalcarata Schipczinski; S. simulatrix J. R. Drummond & Hutchinson.

Things have changed and, the genus Semiaquilegia Makino, is now recognized as a sister genus to Aquilegia (based on petal evolution and geographical affinities). It includes tuberous , herbaceous plants which differ from the genus Aquilegia L.

To set the record straight, we should use only the name Aquilegia ecalcarata. In keeping with my good sowing tradition for Aquilegia, I just treated a few seeds with GA3 500 ppm solution.** Sowing will follow tomorrow (cold/moist stratification for 1-2 months works very well, I just want to start them early).

* Extended phylogeny of Aquilegia: the bio-geographical and ecological patterns of two simultaneous but contrasting radiations:
http://www.plant-animal.es/pdfs/Bastida.et.al.2010.Pl.Syst.Evol.pdf

**For those in need, a reminder that they can read about GA3 preparation and utilisation on the Germination page: here

Friday’s more new seedlings

Today, few species from the sunny, wind swept rocky hills of Dobrogea region (Romania). There are no plans to collect there again soon, so I suggest to take advantage while possible.

From the ‘to try again’ list: Paronychia cephalotes. Interesting, showy and not often cultivated, the seedlings are not difficult to grow; I even enjoy it in the rockery for a while. Sadly it never went any further. I suspect the limestone based substrate had something to do with it.

Paronychia cephalotes germinated seeds

From the ‘sow while still available’ list, from the same habitat with Paronychia: Minuartia glomerata and Thymus zygioides (and few others not yet germinating).

Minuartia glomerata germinated seeds

Thymus zygioides germinated seeds

I also recommend Hedysarum grandiflorum.  My young plants were looking good when last I saw them in late November. The seeds were germinated using the ‘hot water method’  – again, a very useful method for germinating any species within the Fabaceae family.

Paronychia cephalotes

Thymus zygioides

Hedysarum grandiflorum

 

 

New & again

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Some of the newly sown seeds are starting to germinate!
Warm germinators sown in February and grown under lights indoors, can be acclimatized outdoors in April/early May and in many cases planted in the ground by June. At least that’s my method, and I recommend it to those from a cold climate. The young seedlings are establishing fast in the ground and by late fall have developed a good root system to withstand the winter. An examples of last year with: Cerastium alpinum var. lanatum and Minuartia verna. By late summer Minuartia was also flowering.

Also from the screes and rock ledges of Carpathian Mts., the newly sowed Acinos alpinus is starting to germinate. I suspect it will be an easy to grow species at the edge of the rockery.

Acinos alpinus germinated seeds

Besides sowing new species, I also re-sow species with which I wasn’t successful, yet (from various reasons). Anthemis carpatica ssp. pyrethriformis, it is one of these species and I will persevere. It may be that I still have to found a proper location for it in the garden/rockery. In the featured picture, seen last year in July.

Anthemis carpatica ssp. pyrethriformis newly germinated seeds

More to follow….

There are many other warm germinating species in the Shop that can keep you company :) or maybe you got seeds from seeds exchanges or other sources. This is the right time to sow, if using indoor lights.

*For those who don’t use indoor lights and can only sow outdoors: keep the seeds in the fridge and start in late April/ early May (depending on the weather).

Acinos alpinus

Cerastium alpinum ssp. lanatum1

Acinos alpinus and various

 

Fridays Frits

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Do you wonder about your Fritillaria seeds/seedlings/young bulbs? Wonder no more.

With many thanks to a very impatient grower, we can have a look at Fritillaria recurva little bulbs. Also, at my germinating seeds of Fritillaria atropurpurea.

The one-year old bulbs were found at the bottom of the pot. Fritillaria seeds are adapted to wind dispersal (like many Liliaceae actually) and should be sown superficial; then, the growing seedlings will adjust the bulbs to their desired, proper depth.

Fritillaria recurva: seeds to one-year old bulbs

My stratified seeds of Fritillaria atropupurea on Jan. 1st are starting to germinate (1,5 months of cold/moist stratification). And, by the look of the embryos, Fritillaria affinis will follow shortly.

As I already mentioned,  I’m not much of a Frits grower. I’ve grown a couple of species (non-flowering yet) and only this season I have sown more. By the way it goes, it is best to grow the bulbs in the same pot for two years; if necessary transplant the whole content of the sowing pot in a bigger one, keeping the bulbs at the same depth.

Fritillaria atropurpurea germinating seeds after 1,5 months cold/moist stratification (fridge)

If you have pictures related with the Frits species seeds purchased, please don’t hesitate to share!

 

Ephedra distachya revisited

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By tradition in February I start the so called ‘warm sowings’: species that will germinate at room temperature. The seedlings are grown under lights indoors and by April/early May can already be acclimatize outdoors; in most cases, they are planted in the ground shortly after.

It is also a time when warm germinating species are re-tested for germination. Most species keep good germination rates for +/- 5 years (kept dry/cold) but there is no data available for all.

So, I considered necessary to re-test Ephedra distachya. It seems that the seeds are in good standing, starting to germinate in water in a few days. For those interested – the seeds are back in stock! If you want to grow something beautifully ‘different’, this species is for you.

Watch its journey from seeds to young plants in the plate below. This Ephedra likes hot summers, and it was no surprise that after a slow start in May/June (rainy & cold in 2019), has put up a nice growth from August till late fall.

Ephedra distachya 2019 journey from seeds to young plants in the ground; a reminder that it is a dioecious species – keep and grow a few seedlings for assurance of female/male plants ratio

The ‘warm games’ are declared open at BotanyCa; stay tuned for more seeds/seedlings happenings!

Spetlem: Lewisia rediviva

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The bitteroot seeds I sown a month ago have sprouted. I looked at the little seedlings and thought about their story; the story of spetlem, from a time when the species wasn’t even yet described!

Lewisia rediviva seedlings; seeds sown January 4th, kept at room temp. for +/- 10 days, then in the garage (+/- 5C). I was planning to put the sowings outdoors but there was no snow for a while…The germination pattern can vary depending on the collection site (origin for these seeds: Butte Co., California)

An excerpt from an article recounting the discovery of the species during the Lewis and Clark expedition, available here: http://www.lewis-clark.org/article/311.
“An old Flathead Indian woman sat weeping on the bank of the In-schu-te-schu, or Red Willow River, in the shadow of the Chi-quil-quil-kane, or Red Mountains, singing a death song for her starving children. The rising sun heard her plaint, and sent a red spirit-bird to comfort her. The bird promised that from each of her falling tears a new flower would grow, tinted with the rose of his feathers and the white of her hair, and springing from a root as bitter as her sorrow but as nourishing as her love. The prophecy came true, and her people called the plant spetlem -“bitter”.”

Lewisia rediviva in flower; with many thanks to the provider of the picture.

How the bitteroot came to be collected during the Lewis and Clark expedition(1804/06), how it was named and by whom, and more importantly how profound this little species was intertwined with Indigenous Peoples  lives – I hope you will read about it all in the article provided. It is a great story, especially for a cold, snowy day!

Advice for growing it, and more beautiful pictures, in this thread from SRGC forum: http://www.srgc.net/forum/index.php?topic=15817.0

 

Tuesday exotica

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Let’s indulge in few ‘exotic’ late June flowers today. Roscoea species, regardless if they come with small or larger flowers, always bring a ‘tropical’ look to our cold climate gardens.

They are not difficult to grow from seeds, only require patience and I’m happy that more local customers have taken advantage of the seeds offered. Mature plants can be quite expensive when available and I consider that younger tubers will adapt better when planted in the ground.
I gave advice about planting them in this post: Contractile roots – a journey to the center of the earth?.

The tiny R. tibetica fo. atropurpurea fits better in a rockery nook or a container planting. The plant shown below close to Hepatica acutiloba is the result of a ‘location’ experiment; the Hepatica leaf is good for size scale!.

Clockwise: Roscoea scillifolia fo. atropurpurea (small but striking dark purple flowers), striped Roscoea cautleyoides form, Roscoea cautleyoides ‘Kew Beauty’ (flowers of a delicious creamy color) and the tiny Roscoea tibetica fo. atropurpurea ex. B-15 (seeds offered some years)

Here’s a better look at R. tibetica fo. atropurpurea:

Results on Rubus chamaemorus germination – update 2 and 3

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For those who didn’t follow the story from the beginning, please see these links:
Homework for today: Rubus chamaemorus germination – December, 2019
Preliminary results on Rubus chamaemorus germination – update 1 (Jan. 10, 2020)

Lot#2 has been eliminated (the seeds were damaged during the endocarp removal).

Lot#1 – the first signs of germination appeared pretty fast, with the radicle emerging first, in most cases.
A few seeds were also discarded, but almost all the remaining ones showed signs of germination (radicle growth and greening of cotyledons).
The container/and the pot with transplanted germinated seeds have been kept under light at +/- 20C.

Rubus chamaemorus seeds starting to germinate, Jan 19

Rubus chamaemorus germinated seed

The main aim of the experiment was to see if the seeds indeed germinate at warm/room temperature, and they do.
But excising the seeds from the pyrenes is not an easy job and many will get damaged during the process. Especially for large lots of fruits, it is a completely unpractical method.

Rubus chamaemorus pyrenes: hwt x 3 times, placed at warm/light

Another attempt is being made by using a hot water treatment (hwt) on the pyrenes. The hot water treatment gave excellent results last year for replacing the mechanical scarification usually employed for Fabaceae seeds.

Lot#3 was treated with boiling water 3 times, one day after another starting on Jan. 16, and then placed in the same conditions like lot#2. We’ll see if the treatment was enough to produce fissures in the endocarps and allow germination without extracting the seeds.
Update will follow.

 

Recap:
If Rubus chamaemorus fruits are sowed, they require 270 days of cold/moist stratification in order for the endocarp to broke down and allow the seeds to germinate. Translation: for fruits sowing in late fall, expect some germination in the third spring after sowing.

If you manage to remove the endocarps without damaging the seeds, they will germinate quite fast at warm (room temp.)/light.

 

Update 3 – regarding germination trials out (2021):

First, because I had a question about it: what went wrong with excising the seeds from within the pyrenes?
The problem was that using a very sharp scalpel, the seeds were damaged while cutting through the pericarp. Microscopic cuts or punctures led to the damage of the seeds and embryos.

Unless one is a surgeon, I don’t see it as a feasible method, even if the few unharmed seeds did try to germinate.

So, in early spring of 2021 I went back to a classical method of scarification used by plant nurseries for this type of ‘seeds’ by using  sulphuric acid. This is not something that can be applied at home and I don’t know if it is much in use in the nurseries nowadays; out of curiosity I had to give it a try.

One lot of seeds was treated with sulphuric acid for 45 min and another one for 1 h.

Rubus chamaemorus pyrenes – H2SO4 treatment in April 2021, kept in Petri dish on moist towel; picture taken Sept. 12/2021

Afterwards, the ‘seeds’ were kept under lights at room temperature, and… nothing happened. Some seeds seem a bit enlarged but obviously the time wasn’t enough for the endocarp to be eroded enough in order to allow water imbibition.
Later on I found one study suggesting a 3h treatment with sulphuric acid; maybe I will try it this coming winter.

 

Also, another more friendly method, like nicking, was also tried with no success.
Then I left a sample of pyrenes sitting in water since March! I thought that some may give in and imbibe but it didn’t happen.

 

Rubus chamaemorus pyrenes – after receiving hot water treatment x 3 times in spring 2021, then kept in water (regularly changed); picture taken Sept.12/2021

Conclusion: for home gardeners sowing as usual and patience may provide the best outcome in regards to germination of this species. Repeated cycles of warm/cold/warm/cold are necessary for the endocarp to broke down and allow water imbibition of the seeds and start the germination process.

Friday’s Seeds: Rosaceae on the wind

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“All the flowers of all the tomorrows are in the seeds of today” – with this being said (I don’t remember by whom), the Friday’s seeds series starts again. Rosa family is extremely large and diverse, with many ornamental species. Equally diverse are the fruits and seeds.

Apart from the well-known species with fleshy fruits many are familiar with, many others have dry fruits, of which some are adapted for wind dispersal. For this purpose, the styles remain attached to the fruit and begin to elongate after pollination; they also develop hairs in various amounts and many times the fluffy ‘seed-heads’ are nice additional ornamental features. The featured image shows the alpine Geum reptans with developing fruit-heads.

What we usually ‘seed’ is actually the fruit, which is an achene; inside it holds one seed. Few examples:
This year good fortune made it that we can compare two mountain avens species: Dryas octopetala and Dryas oxyodonta seeds.

Dryas octopetala seeds

Dryas oxyodonta seeds

Also, we can have a look at the Aleutian avens, Sierversia pentapetala seeds (syn. Dryas pentapetala).

Sieversia pentapetala seeds (syn. Dryas pentapetala)

The genus Geum contains a lot of species cultivated in the gardens. It would be hard to distinguish them after the ‘seeds’ but we can at least define the genus.
Geum triflorum (Prairie smoke) and Geum rivale (Nodding avens) shown.

Geum triflorum seeds

Geum rivale seeds

And, finally, something like a Geum on steroids if someone cares to google for plant pictures: Woronovia speciosa.

Woronovia speciosa

Drya octopetala

Sieversia pentapetala

Geum triflorum in June

Geum rivale

Blue-eyes Wednesday

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The June garden review (in progress) it is a good occasion to update the info on Sisyrinchium mucronatum (Slender blue-eyed grass).
Seeds offered as S. montanum for a couple of years were probably a mixture of both species (please see the note on the S. montanum page).

When the light blue, delicate flowers start swaying atop of the grassy leaved tight clump in June, I always wonder why we don’t cultivate more the blue-eyed grass species.
Besides their beauty, all are super cold hardy, pollinator friendly, not requiring a lot of space and good companions to other native and non-native species.
Close to S. mucronatum I grow Primula mistassinica, Parnasia glauca, Viola nephrophylla; last summer were added young plants of Zigadenus elegans and  Prenanthes racemosa. Any other species preferring a slightly moist location (even temporarily flooded) in full sun to part-shade, would be good companions.

Sisyrinchium mucronatum (Slender blue-eyed grass) flowering in June

Preliminary results on Rubus chamaemorus germination – update 1

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January 10, 2020
The first post on R. chamaemorus (December 2019): HERE

First, a simple, short presentation of the Rubus fruit so that we understand the photos. The fruit is an aggregate of drupes. Each drupe presents a fleshy part (intended as a reward for dispersers) and a ‘pyrene’ in which the seed is protected by the hard fruit endocarp similar to the peach stone. Inside the pyrene, there is a seed covered by a thin seedcoat.
The embryo in Rubus species is fully formed, showing a small radicle and two large cotyledons.

Rubus chamaemorus pyrene

The endocarp of the pyrene is very hard, reason for the difficulties in germinating the seeds.
We shall see how to remove it in a simple way and determine if the seeds germinate at warm or need a cold period, to clarify the contradictory existent sources. I realize now that this may be due to the fact that some people tried to germinate the pyrenes while others tried the actual seeds!
When sowing the pyrenes, 270 days of cold/moist stratification are said to be required for germination, meaning 2 years (Baskin & Baskin).

Two lots of pyrenes were used.
Lot#1 was soaked in water since Dec. 18, with the water changed once in a while.
Lot#2 was soaked and also treated with hot water twice at interval of one week (see the ‘hot water treatment’ post).

I sectioned the first few pyrenes last week just to see how it goes, but the germination experiment was started only two days ago; that means about 3 weeks of soaking in water.

The endocarps were removed with a scalpel under a magnifying lamp. The easy way to remove them is by making a small section on the curved side of the pyrene, towards the rounded end. This way you avoid damaging the embryo radicle, which is at the opposite end.

 Rubus chamaemorus; pyrenes showing where to section to remove the endocarp

Despite the recommendation of the article presented in the first post, I find no need for nicking the seedcoat, which is very thin and sometimes even slides out easily (especially in lot #2).

Findings: the pyrenes treated with hot water were definitely easier to cut than the ones only soaked in water. For lot# 2 some of the seeds were already soft, a sign that the soaking time was too long. It is clear that the hot water treatment is very effective, leading to fine fissures in the endocarp. The soaking time should be reduced a bit, maybe at two weeks.

After removing the endocarps, the seeds were placed right away in containers (with lids) prepared with a layer of moist vermiculite and a coffee filter on top; this will allow for easy observation. I borrowed the idea from a friend who used it for stratification of seeds in the fridge.

The seeds (some still with half of the endocarp) and the embryos are sitting on top of the coffee filter, which can be easily replaced in case some of them develop mold (quite possible)

Considering the aspect of lot#2 of pyrenes and seeds, I wonder if the hot water treatment (done a bit differently) may not be enough to allow the seeds to germinate (?). I still have a small lot of pyrenes and will start one more treatment right away.
Removing the endocarps is not a practical solution for large scale sowing, plus other Rubus species (all with hard endocarps) have very small pyrenes.

So, until the next update – let’s have the kettle going!

Special thanks: to Trond Hoy for providing the bakeapple seeds and to Keith Baldie for sharing with me his method of stratification.

Practical considerations for sowing in late fall and winter

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For those who don’t know it yet…the devil is in the details, sometimes.

Updated to: sowing in”late fall-winter” (for those in cold climates, zone 6 and below)

Sowing in late fall – early winter – what is different than fall sowing?
Most important is to consider that seeds must enter the cold cycle well imbibed with water. When sowing in late fall when temperatures are still well above freezing, this is not a problem. By the time the cold arrives (meaning temperatures around 0C and below), the seeds have already soaked a lot of water and will enter the cold stratification well prepared.

But when sowing in late fall (November) and advancing into the winter, even if the pots are well watered, the seeds may not be able to absorb the water fast enough when they are placed right away outdoors.
For this reason it is best to keep the new pots with sowings indoors for about 2-3 (4)weeks, and move them outdoors in the cold after that.

The same concept applies if you want to start the cold/moist stratification in the fridge.
Place the seeds in the moist medium of your choice (vermiculite, sand or wet towels) and keep them at room temperature first for a few days, before placing them in the fridge. You will be surprised by the change most seeds will undergo while absorbing water in only a few days.

I can exemplify with Fritillaria and Tulipa seeds that I plan to grow under lights indoors. In this purpose I kept them at room temp. for about a week before placing them in the fridge; in some cases the embryos are already visible (hover the mouse for names).

Tulipa tschimganica seeds

Fritillaria latifolia seeds

Talking about stratifying seeds in the fridge, please consider first what species you want to germinate. Most are best sowed and placed outdoors.
In the case of species known to require low temperatures for dormancy breaking (like various Gentiana, Saxifraga, most Ranunculaceae), stratification in the fridge at +/-4C is not a good option (unless you have a fridge dedicated to seeds and can vary the temp.).

True that in case of a mild winter seeds may not germinate in the first spring, even if sowed outdoors! Breaking the dormancy requires temperatures below zero for various periods of time, and if specific cold period requirements are not satisfied in the first winter, the seeds will need an additional cold cycle to germinate. In this latter case, keep your pots and take care of them until the second spring.

Talking moist packed seeds: a reminder that these seeds are in full development by late fall (their warm cycle completed and the cold one started), and in some cases there may be signs that the radicles are just about to emerge (a classic example is Asarum canadense which always starts to germinate somewhere in November; if they get too advanced then the shipping will be stopped).
The moist packed seeds require a cold cycle for breaking shoot dormancy at this point, so they should be sown asap and placed outdoors. best option is to use a cold frame, cold garage, or in absence of these options bundle them together and fingers crossed for snow (the pots can also be covered with a thermal fleece, tarps, in case it gets very cold with no snow cover).

To finish about spring Corydalis

Before the year’s end, here’s a bit more about Corydalis solida and the likes (other tuberous species).
This is probably a repeat of what I have previously mentioned, but it is good to recap.

Corydalis solida and the likes (C. caucasica, C. cava, C. malkensis…) are promiscuous species, cross-pollinating freely, which means that growing them from seeds, there is no guarantee you will obtain the same form as the mother plant. But precisely in this ‘flaw’ I find their beauty because interesting forms can appear naturally; all one has to do is pay attention and select them.

A beautiful form of Corydalis caucasica ex. ‘Alba’.

Corydalis caucasica ex. ‘Alba’

Two other C. solida seedlings I am ‘watching’: a deep red one and a red with pink lips (most likely a cross from ‘Beth Evans’).

C. solida seedling1

C. solida seedling2

Nothing is easier than growing this type of Corydalis from seeds. The seeds are ready toward the end of May, and if you want to actively increase your stock, it is best to collect them; otherwise, the ants will carry them maybe in places where not all the seeds can germinate.

Fresh sown seeds will promptly germinate in the following spring (after a warm/cold cycle), grow for few months and then go dormant. My method is now to grow them in the same pot for 2 years and at the end of the second cycle to plant the small tubers in the ground (June/July).
In most cases, the first flowers will appear in the third year.

Corydalis solida- 1 and 2 years seedlings

Corydalis young tubers

Corydalis solida old tubers

Older tubers can be dug up and moved in the summer after the plants have gone dormant; part-shaded locations which do not dry completely in the summer are best.

Happy Corydalis growing!

 

How about those spring Corydalis?

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OK, few pictures of sunny spring days will do good for a dark and rainy (icy for some) late December. Regular readers here will observe that there is a new one added to the collection!
More, including tubers pictures and how to easily grow them (yes, I will repeat it many times), next time.

All pictures: forms of Corydalis solida and Corydalis malkensis.

Corydalis solida

 

Corydalis malkensis