Our abiding passions are seed and germination. We do extensive public speaking and have, over the years, written many articles on various aspects of seed and germination. Our own in-house work with germination is of an on-going nature and ultimately reflected in the germination information you find on our seed packages. However, we plan to use this site to post new discoveries and developments as they arise and urge you to visit regularly. We also hope that many of the questions raised by you in correspondence relating to germination, seed collecting or storage will be answered here, where they can be of benefit to everyone and that you will find the responses helpful and informative.
All articles copyright Kristl Walek 2002Germination Basics
Recommended Germination Books
Adlumnia fungosa and Ampelopsis brevipendunculata
Do good seeds sink and bad seeds float?
Germination Of Gentiana, Primula and Saxifraga
Working With GA-3
Collecting Tree Seed
Growing Ferns From Spores
First: organize seeds into "germination types" (warm-germinators, those requiring cold, etc). Provide pre-treatment if necessary (soaking, puncturing impervious seed coats, washing etc.).
The Easy Warm Germinators
These are indicated as "easy, warm germinators" after the description
in the catalogue.
Seed Requiring Cold Conditioning
- The conditioning you must provide is moist and cold. In other words,
you are not doing anything to your seed to enable it to germinate by putting
your DRY seed in its package in the fridge or freezer. The seed must be
sown in moist soil-less mix (as above) and placed in the cold.
The Multi-Cycle or Extended Germinators
These are the more complex seeds to germinate as they sometimes require
Kristl Walek 1995
You will have noticed that reference is often made to germination with
GA-3 is most normally used, but there are in fact, many different types: over 67 gibberelins have now been isolated. Sanguinaria canadensis (our native Bloodroot) appears to give the best results with GA-7, obviously present in woodland soil where it naturally grows. Germination of this seed by any other method has proved futile.
Some genera have germination dramatically stimulated by the use of GA-3 (Thalictrum, Viola, Aquilegia). However, this does not mean that germination is impossible without it. And to the ordinary gardener, obtaining maximum rates in a scientifically reproducible manner is rarely essential. In some cases, the use of GA-3 is detrimental or even fatal to seeds. Few plants absolutely require gibberelins to germinate.
Dr. Norman Deno,
Seed Germination Theory and Practice
First Supplement to Seed Germination Theory and Practice
Second Supplement to Seed Germination Theory and Practice
Dr. Deno has now turned his attention to the study of seed storage and
I am sure we can
Even though we are a Canadian company, we use USDA Hardiness Zones in rating the seed in our catalogue. Our business is international, and the USDA ratings are more widely known and understood by gardeners throughout the world.
The term "hardiness" refers to a plant's ability to survive (and thrive) in the normal climate where it is planted. Many factors, aside from heat or cold, influence the hardiness of a plant, including sufficient opportunity to acclimatize, the amount of wind, rain, sun, snow cover, drought, humidity, and soil. Also, within each climatic area, microclimates occur (caused by such factors as altitude, exposure or shelter, proximity to bodies of water) which can affect a plant's hardiness.
That aside, I would like to see hardiness zones entirely abolished, at least for herbaceous plants, as I believe that they influence gardeners negatively. For woody species, I pay more attention.
Hardiness ratings in the catalogue are based on our experience in a Zone 4 garden, as well as the input of our customers over the years who garden in much colder areas.
Average Annual Minimum Temperatures
"Do you have any comments on either Adlumnia fungosa or Ampelopsis brevipendunculata? Does the Adlumia re-seed well? Is it easy to start from seed?"
The Adlumnia fungosa is one of our most popular seeds both retail and wholesale. This is a subtle woodland plant with lovely ferny foliage and while it performs well in full sun I find the (already pale) pearl pink flowers look washed-out and less effective in this position.
We have it scrambling over some of the tall stumps of sugar maples we left standing after the ice storm. It is interesting to note that while it is a tendril climber, in the wild it is most frequently found on shady woodland slopes, acting like a groundcover.
Adlumnia fungosa is a biennial and self-sows copiously. However-- there is something important you must be aware of if you are to establish it as a permanent resident of your garden, which it eventually will become. And it is this: unlike so many biennials which are easy, warm germinators, this species requires cold to germinate. Translated, this means that unless you plant it for the first TWO years when you are seeking to establish it, you will not have it permanently.
I believe I need to explain this further. Assume you grow it from seed this winter. You plant those seedlings out this coming spring. This is not a plant that will EVER flower the first season, or in fact show any signs of being a climber at all. It simply stays as a neat rosette of ferny foliage, no matter how early you set it out in the garden. That rosette will winter over to flower (and produce seed) the second year. However, here is the hitch....the seed that falls the first year of flowering will only become that same-self low rosette of foliage the following year. You will have no flowering plants that season. So, in other words, for you to get into rhythm and have this plant self perpetuate, you need to set out seedlings both the first year and the second year, allowing the first batch you grew to self-sow its flowering year. I hope this is clear.
Even if you find plants to purchase, you will have to purchase them for two years running. Better to grow them from seed!!!!
There are a number of Ampelopsis (Porcelain Vine) species, and we have carried the seed of many of them over the years (aconitifolia, brevipendunculata, humulifolia, with a few others in the wings). In the garden, the differences between them usually comes down to foliage. They are all tendril climbers.
Ampelopsis brevipendunculata (native to Asia) and its variegated form "Elegans" are the ones most commonly found in the trade. This is an extremely vigorous climber & should be watched. It also self-sows with abandon, requiring cold to germinate. It will normally flower and produce berries its second year from seed.
As mentioned earlier, the variegated form comes true from seed, requiring a year to fully manifest its variegation. Many of my variegated seedlings are in fact much more striking than their vegetatively propagated mom. You can simply choose to keep the plants exhibiting the best variegation.
We grow most of our species in full sun, but they do equally well in part shade and the variegated form looks better there.
The flowers are entirely insignificant- they will come and go without notice; and notwithstanding its rampant habits, I could not live without this plant in the fall garden- there is nothing that carries my late season like the absolutely beautiful berries of this plant, in shimmering shades of porcelain blue, turquoise and amethyst-purple, often all at once. Michael Dirr has commented that this plant is perhaps unrivaled by any other woody plant in vitality of color.
"While cleaning seed I observed that some of the seeds floated in the bowl of water they were in, and some sank. I assume that the "floaters" should be discarded because they are likely "empties" anyway."
While in some isolated cases it might be true that floaters indicate a seed without embryo, it has not been my experience over the years testing many thousands of species, that this old "rule of thumb" has much basis in reality. I would never reject the floaters for this reason alone.
It is perhaps the case that many of these notions are simply accepted without thought, on the basis of common sense and further investigation is deemed unnecessary. However there are other reasons, aside from the lack of an embryo that would cause a seed to float.
And the only way one ever finally does answer the question is to take the experiment through to its logical conclusion- and that is to sprout both floater and sinker. Doing this will lead to surprising results.
Unfortunately, often the myth, rather than the science is what remains.
Norm Deno has the following to say: "The notion that all good seed sinks in water and bad seed floats is just not always true. All Iris setosa seed floats even after a month in water. In fact, it starts to germinate after a couple of weeks floating. Iris pseudoacorus seed floats for a few days and then all sinks. Large sample seed of Cornus amomum were collected from our own colonies and after thorough washing and cleaning, about half the seed floats and half sinks. Both types gave about the same germination both in percent germination and in the rates and other germination characters."
"In September 1999 I sowed some seeds of Paeonia suffruticosa in a seed starting mix in zip-lock bags, planning to alternate them between 70 and 40 F. I started them at room temperature. Today I noticed that a couple of seeds have already germinated. Should I transplant them into separate pots immediately or let them stay in the bags during the cold period? I believe they need a cold period in order to send up a leaf?"
You need not be in a hurry to get them in the fridge. I often wait for a while, until more seeds germinate; because often once they start, more are not far behind. There is absolutely no harm to leaving the already germinated ones in the bag, while you wait. They will not do anything else anyway at this stage, and they will not die, so don't worry. I have been down this road many times.
If you are keen to get the cold period started, you could prepare another ziplock with barely moist seed starting mix and start transferring the germinated ones into it and continue to add to the bag as more germinate.
To clarify, all the seed does at the initial warm is germinate (send out the radicle). Absolutely nothing further. You could keep it at the warm stage for months (and I have done this) after germination, and it will proceed no further. It requires the cold period to form a rather extensive branching root system. This can take anywhere up to 3-4 months. So what you will be doing at the next stage is keeping an eye on the zip-lock in the fridge. Once you see that any of the seeds have formed this kind of root system (it will be VERY obvious) then take that seedling out, pot it up and put it under lights in warm. It is only then that the first true leaf appears (at this final warm stage)...The seedlings will be huge, and quite satisfying to grow on.
I spent most of today dealing with a large variety of species Paeonia seedlings that have been in zip-locks at various stages since last winter. Some were left almost the entire summer (as I did not have time to deal with them) in their zip-locks and yet are as healthy and vigorous as if they only needed to be potted yesterday, instead of months ago.
Some plants are very forgiving, and the zip-lock bag method forgives those of us with more seedlings than time on our hands.
Hellebores are ephemeral and need to be sown fresh. They also germinate as temperatures fall, not rise, making them a bit awkward to deal with in a cold climate. However, they are exceedingly simple to sprout, once you understand this. In their native haunts, they germinate in late fall/early winter. One wonders how they manage to survive until spring; that is, until you have seen their root systems, even at germination.
Growth Rates For Hellebores H. niger, orientalis and its hybrids Extremely slow glowers, usually taking a full year to progress to their first few true leaves stage. Thereafter, they continue to grow slowly and can take from 3-5 years to flower. They are happiest if set out in the garden early the first spring, while small.
H. foetidus and hybrids Extremely fast growers. Can fill a 6" pot in a single season. Will flower the second year. For nursery persons and growers: first year plants will be more than saleable, they will be huge. Foolproof Method for germinating fresh Hellebore seed While you should feel free to devise your own method (understanding the above general principle of germination), here is what we do, with consistently good results each year.
Sow the seed as soon as possible in a deep and wide pot. Water Leave pot anywhere outside in the shade where you will remember to keep it watered throughout the season and into late fall. Allow the pot to stay outdoors as late as possible in the season, hopefully after it has had a few frosts behind it. Peek at the pot now and then and if any germination has started, go to step (5) immediately. I normally do not have germination at this stage, but it could happen. After a couple of freezes outside, place the pot in a COOL (but not freezing) spot inside. Ideal areas include: An unheated garage A cool basement or extra room that is unheated. I bring the pots into my office. This space is heated, but often not yet at this time of the year. However, even when it is, the furnace is ceiling-mounted and heat stays up high. The floor is poured concrete and cool. I place the pots on the floor in the corner I know stays the coolest. Keep pots moist, not soggy and simply wait. The H. foetidus will sprout first, and the niger/orientalis gang later. Germination will occur by Christmas or soon thereafter. Don't panic if the timing is off. Just be patient and wait. Once they start sprouting, they will continue, often, for several months (particularly the nigers and orientalis), so don't assume anything when the first flush of germination occurs. I keep my flats on the cool floor for months after germination starts. They would like to have light once they germinate, so the dark, unheated garage may not work anymore. You will have to improvise. The nigers/orientalis can remain in their original pot (assuming it was deep enough) the entire winter. The foetidus will need transplanting fairly quickly. I seem to recall the first winter I did this, transplanting them twice before spring. They were monstrous. And wonderful. Plant out in the garden as soon as possible in spring, where they will be happiest growing along.
Over the past few years, I have been working consciously on increasing my collection of Primula, Gentiana and Saxifrages. ( I like to attack genera, finding it a good way of getting to know the species and their habits).
The problem with all 3 genera is their rate of growth (particularly the
Gentians and Saxes). And because I already know that the summer is *my*
most vulnerable time in terms of taking care of small plants, I began
to alter my sowing habits. I did not want to deal with *just germinated*
or tiny seedlings from May-August, when I would surely lose them. And
certainly not primula, gentians or saxes!!! So, last year I abandoned
sowing these genera
The seeds of the 3 genera are sown now, and by spring I have decent sized primula that can either go straight into the garden, or even on the benches for sale. I am not struggling to get some choice tiny species through the hot summer and then losing it anyway to stress or drought.
Because primula are largely a genus of warm germinators, the simple change to sowing at this time of the year has made a tremendous difference to my survival rate.
However, the issue is not so simple with gentians and saxes. They not only have various germination requirements, but it is only the exceptional species that could ever be large enough the same year of sowing to amount to anything. If on top of slow growth there is cold conditioning required, one is set back even more.
I knew that Norm Deno had only begun his experiments with GA-3 on both gentians and saxes and made a threshold recommendation of trying the treatment on more species. And so I did- on all gentians and saxes across the board, some 54 or more species. They were sown approximately 8 days ago, all treated with GA-3. And today there was a most pleasant surprise. A solid 2/3 had germinated, and I intuitively feel optimistic about more.
I had already known about the dramatic effect of GA-3 on Gentiana verna and Saxifraga oppositifolia. But I was thrilled to see massive germination of Gentiana clusii, dahurica, and others. I have germinated Gentiana algida before without cold treatment, although sprouting was very sparse and prolonged. It looks as though it germinated 100% and the seedlings appear healthy, at least at this small stage.
Kristl Walek (Post on Alpine-L November, 2002)
"I have not developed a good method for treating seeds with GA-3 and then getting the treated seeds planted. Would you please describe your procedure?"
All of us who play with GA-3 know, certainly, that it has a reasonably
long lifespan, kept refrigerated.
A good way to check the viability of your GA-3 is to do a quick test run with a seed that obviously needs or benefits from GA-3. I often use Thalictrum as my "test seed", because it will usually not germinate at warm at all, unless treated with GA-3. If it sprouts at warm within about 10 days, your GA-3 is fine.
I should note that the insert that comes with the chemical states viability of "3 months." This obviously refers to the concentration, once mixed with water. And I suspect, refrigerated. I do know that one cannot use mixed concentration for too long.
Now, as to my procedure, it is hardly high art. Depending on the size of the seed, and how lazy I am, I normally do one of two things.
Last year I forgot (for too long) batches of Opuntia--which proceeded to sprout almost instantly, but many ended up weak, etoliated and eventually expired. Whether from the GA-3 or from too long of a soak still needs to be re-tested.
After the soak, I transfer the seeds to my pot of soil-less sowing mix (already pre-moistened with water in the normal course of events), pour the GA-3 soak mixture over the seed (just for good measure) and place under lights.
I know that many people soak even small seeds, but I find this very difficult, particularly the getting-it-sown-afterwards part. It is very difficult to *pour* small seed into a pot and not have it all end up either sinking in or sitting in one wet clump. Then, annoyingly, one has to separate the clump with a tool, it gets stuck to the tool, etc. A never-ending frustration. But I am not a patient woman.
I do believe, however, that the soak probably gives the best insurance that the seed has taken up moisture (and the GA-3). Although its presence in the medium (as in the soil, leaf mould, in nature) is likely enough.
Seeds are sown on the surface of their pre-moistened pots (pre-moistened with water, in the normal course). If not pre-moistened, the GA-3 mixture will simply disappear into the dry soil-less mix.
I do up a concentration (how much depends on how many seeds I am treating). This is by feel. In the past I would put the concentration in a spray bottle and simply spray the surface of the pots. I found I had some success, but less than satisfactory results, so now I spoon. Using a teaspoon I simply spoon the GA-3 and water mixture evenly (but generously) over the surface of the pot where the seeds have been sown.
Cover the seed to retain moisture and put under lights. I try not to have to re-water during the germination process, so that whatever concentrations of the GA-3 are "in there" don't get washed away, diluted, whatever. It seems to work well.
Kristl Walek (November, 2002)
For someone whose life is her work, the days of late summer are consumed by seed. The most intensive harvest time has begun, at least for larger, herbaceous plants. Most of the alpines are finished and the woody species will begin, in earnest, later this month and continue until the snow flies. The garden is always secondary now; there is no time for tidying or late planting.
I must be organized- various scissors, secateurs, gloves for cacti and prickly beasts accompany me, along with the bags (both paper and plastic). Dry seed in one, berries and fruits in the other. I drag along a huge cart, so that I will not have to return to base camp too often. On lazy days, I drive the Kubota around the 8 acres, to which a cart is attached.
It is still hot, so the collection begins early, resumes in the late
afternoon, does not end until the light is gone. During the worst heat
of the day, I retreat to my office and clean seed. The large-grocery-store-brown-paper-bags
have filled the greenhouse twice, 583
There are sieves of every size and shape, something I am always on the
look-out for at kitchen supply stores, garage sales, second hand shops.
I buy the expensive stainless steel ones, whenever I can, for longevity.
The tools of my trade. The sieves, and the bowls. My favourite is a particular
antique wooden bowl- just the right size and angle for seeds, and no static.
It gets used for tossing the seed - and once you master it, the chaff
There are other implements- face masks become essential for irritating
seeds. Gloves a must for fresh Hellebore (I will not tell all of the gruesome
recent tale of purple and green fingers, swollen twice their normal size,
with all feeling gone for a week, after the initial, fairly excruciating
pain, and then the skin peeling stage. And rubber gloves with a
And then there are the berries. Today the office smelled of ripe fruit,
of strange wine. I was cleaning Arisaema, Clintonia, Arctostaphyllos,
Vitis, Cornus, early Viburnums, Roses and Euonymous, Late Actaea, Aralia,
Sambucus. These (except for the Arisaema- which gets "popped out"
one berry at a time) are collected in Zip Lock baggies, allowed to soften
a bit in the bag, and then first, squished while still in the baggie,
as this makes the washing
The most unique seed cleaning technique I ever observed was not my own- but a team of Finnish seed collectors with volumes of tree seed to clean and package to ship back to Finland. They had many seeds in large, hard seed receptacles- short of spending days hammering each seed to reduce the volume, they simply drove their car back and forth over the seed.
The collecting will continue, long after the seed exchange deadlines have passed. Will continue through late October-November. Continues sometimes, up to the day the seed catalogue goes to the printer. The seed cleaning chaff is taken out to the field a number of times each day, by wheelbarrow. It is astounding what springs up in that meadow each year.
Kristl Walek (Post on Alpine-L September 7, 2002)
While I collect seed in many environments, collecting tree seed ranks high on my list of pleasurable activities, as this is often done in the forest, where I feel particularly comfortable. Even at the end of a long, strenuous day of hiking and harvesting, I am rarely ready to come home. Luckily, the seeds do not ripen at once, so I must make many return trips (from mid-summer to November, or later).
Trees produce seed in a more interesting variety of receptacles than herbaceous plants and this too fascinates me. Among them are cones, pods, berries, fruits, nuts, wings, and acorns.
For genetic diversity, I try to collect the same species from various sites (more northerly spots for hardiness), and from different individual trees. I choose the healthiest, most productive specimens.
Before I begin, I ensure that I am collecting good seed. First, look for tell-tale holes or spots that could indicate insect damage. Also, avoid taking “suspect” seed- any that are obviously distorted or undeveloped.
Many tree seeds are bulky; Quercus (Oak), Juglans (Black Walnut, Butternut), Fagus (Beech), Gymnocladus dioicus (Kentucky Coffee Tree) or Carya (Hickory) and usually contain one seed per receptacle. Before gathering these heavy seeds- crack the shell or cut through a few of the fruits, if possible, to ensure they actually have seed inside and that the seed is not infected by insects. Live, healthy seeds will be white or green and noticeable plump.
Oaks, Tilia (Basswood) and Acers are often empty or infected. If checked before the seed becomes dry and hardens, this task is easy and can be done with fingernail, penknife or your shoe in situ before the collecting begins.
Color As seeds ripen their receptacles normally change color, starting out green and turning tan, brown, grey or yellow. Ripe conifer cones may still appear green, but their scales will be edged brown. They are ideally picked when tan, but before they open and release their seeds. Open cones found on the ground will be largely empty. Fruits will take on their ripe colors of red, orange, blue or black and may become juicy and soft. Winged fruits, pods and cones will also lighten and become less dense as they ripen and dry.
Opening or Dropping With ripeness, the seed receptacles
may split open, fall off the plant or be carried away by the wind. This
is a sure sign that the seed is ready.
HOW TO CLEAN TREE SEED
After cleaning, store seed that can tolerate drying in paper bags placed
in plastic containers in your freezer (where they will keep indefinitely).
Acorns should be sown immediately, either in situ or in very deep containers
to accommodate their tap roots. Recycled styrofoam fish boxes make ideal
sowing containers for trees. Last year’s collection of shagbark
hickories from northern Quebec were lined up in these and have already
produced a crop of beautiful seedlings. I can already imagine the small
pseudo-forest they will make on my property, their wonderful bark there
to be enjoyed by
Even if you don’t have the space to plant many trees, growing even one tree from seed and watching it mature will fill you up, from the inside out, in the way that only rare and precious things do.
My plunge bed is the single most important propagation tool I have. It is like a cold frame, in principle, except that the plants are kept open to the elements. In 10 years of experience I would say that the overwintering rate of plunged plants has been 85% or higher.
Plants in pots are plunged (dug into sand) up to the level of the soil in their pots. I plant tightly, in rows. I used to keep a bit of sand between each pot as an added insulating factor, but stopped doing that years ago with no detrimental effect.
The only down side is the inevitable rooting of the plants in the sand below the pot. This only becomes a very serious problem with tap-rooted species that have stayed in the plunge for too long.
I have two plunge beds at present, and am constantly thinking about areas to construct more. The main plunge is large: a 30’ x 12’ area where all my left-over nursery stock is kept over winter. The newest is a very small plunge next to my greenhouse in shade where I "hold" and grow on my most treasured plants, the tiny Saxifraga seedlings and cuttings which take years to become thumb-nail size, the Ramondas, Gentians and precious tiny alpine Primula that need more time to fatter up. I can safely keep them here for years, if necessary, with minimal care and attention.
A plunge bed is simple to construct and maintain.
What can you do with a plunge bed?
Kristl Walek - February, 2003
Bored this winter? Cabin fever in huge doses? Why not take the plunge and learn to grow ferns from spores? Baby ferns not only win first prize for cutest infantile plants in the universe (yes, even more endearing than baby trees!) but you will learn firsthand what the term sexual reproduction really means in the plant world.
Start by getting spores from one of the seed exchanges or through the
Fern Society. Each almost-invisible quantity of spores will contain millions
of potential babies, so do not be deterred by what appears to be dust.
Now down to work.
Sprinkle the spores on top of the soil, just enough so that you can see the powdery spores wafting down. Put the top on the container and place under your grow lights or near a window; up close for a north-facing window, back a foot or so for south-facing windows.
Wait. Wait. And wait. It will be about six to eight weeks or more before you see anything. Then you will notice small flat leaf-like plants. These are called “prothallia” and will grow to about 3/8” across. If there are a lot growing close together, they must be thinned out to about one or two per three-inch area. If not, they will grow only male organs. During this time make sure the soil in the container does not dry out. Check regularly.
When the prothallia get to 3/8” male and female organs will develop. The male organ will make sperm which will swim to the female part and fertilize the egg. The egg will then grow into the fern plant that we see, called the “sporophyte.” During this time the prothallia should be sprinkled with water so that the sperm will be able to swim to the egg.
After another six to eight weeks you will see little ferns come up. The first frond will be about ½” tall. Thin them out. In the spring give them a long time to adjust to the dry outside air by opening the top of the container a little bit each day. This open time should gradually increase more and more. If the fronds look bad, close the container until they recover, then try again. This is the stage where most ferns are lost.
Plant them out in a mostly shady spot, but not too shady and keep an eye on them the first year.