What growing medium to use for seedlings? Cold stratification recommendations?

(Orion Potts) #1

Good morning!

I have a few questions about growing from seed. I have a variety of seeds I purchased off seedrack.com, they are in good condition and some of them I have already used with great success! I was wondering, after I cold stratify, what is the best growing medium to use for new seedlings moved from cold strat or no strat? Just sand? Or a mixture of?

When I move them to it, should I use a covered container with a grow mat on all seedlings? Or just move them outside? I plan on started a large variety of seeds which I have from that site :slight_smile: I would love to know any tricks or best practices to make sure I get a great yield!

For cold stratification, I was using paper towels dampened with a solution of water and hydrogen peroxide (I read somewhere that helps with bad mold and fungus while stratifying). Ziplock bags and put into my fridge in a separate drawer for 90 days or until they germinate. This time around I think I am going to use Sphagnum moss with the same solution. Does this sound right? Am I missing anything or does anyone have any recommendations on the cold stratification process as well?


Orion Potts

(Sely) #2

Seems like your on the right track! I just sieve my mix and not the powder but the one before it for seeds. And as for cold strat, I too put them in the fridge because sometimes here in Texas, we don’t get a good 60-90 days of cold. Controlling the amount of moisture in the zip lock is hard, so I drain the water off and put them in a dry fine aged pine bark. Then I say the magic words and presto.

(Frank Corrigan) #3

Hello Orion
For cold stratification i have used the following with good success.
wet paper towels and wring them out to get the excess moisture. Soak some shredded sphagnum moss and wring out the excess, evenly distribute the moss on the flattened towel. place the seeds so they do not touch each other and fold the towel over and over to a suitable size that can be placed in the zip lock bag for the fridge. Ince a month i check the bags and if they need moisture I spray the outside of the paper towel and replace in the zip lock baggy. If the seeds start to sprout early i just plant them right away.

The seedling germination mix i prefer is finely seived pumice with a small amount of shredded sphagnum added to the pumice. This mix tends to stay damp and still provide air in the mix due to the porosity of pumice as opposed to sand. I have had some issues of damping off and anaerobic conditions with sand.With the pumice it is very easy to see if it is drying out due to the change of color from grey to white.
Hope these suggestions help.

(Jonas Dupuich) #4

For pines, I used to do it like this:

but now take a few shortcuts. I use a moist paper towel in a ziplock bag for the cold stratification, and I simply toss them on top of a bed of bonsai soil and cover with finer mix.

As for how long to stratify and whether or not to scarify, I refer to https://treeshrubseeds.com/

(Sely) #5

I sure love that pumice. I use it for everything, especially for my pine seeds.

(Orion Potts) #6

Thank you guys so much for the info! Ill let you know how it goes! I have half in just wet paper towel and half in soaked and drained Sphagnum moss in ziplocks. Both in my fridge! :slight_smile:

(Orion Potts) #7

Does anyone know a good place to get Sphagnum Moss? I have peatmoss but it does not look like the moss I see everyone else using. Mine is fine and not stringy at all.

THanks, :slight_smile:

(Jonas Dupuich) #8

Home Depot and Amazon are two easy bets. Look for the white stuff, usually marketed as New Zealand sphagnum moss or orchid moss.

(Alice) #9

I wonder whether we can use a garden bed like this http://inthebackyard.ca/gardens/ as the growing medium for the bonsai. I read that garden beds have many advantageous like, it can produce more yields. I found that it is easy to prepare the garden beds too.
Is it necessary to grow the bonsai in a pot?

(Jonas Dupuich) #10

Large garden beds, or better yet, raised beds work well for developing material for bonsai. Refining bonsai - developing branch ramification, etc. - takes place in a pot as it limits the vigor of the plant when fine branching is desired.


Jonas, I am currently building a raised garden bed. It’s not the typical bed in that it’s actually more of a table and will be a large 7’x4’ wood box sitting on a metal frame 3’ off the ground and will be about 12" deep. I plan on buying several 4" trees from evergreengardenworks to plant in this box to develop into bonsai. What is a good soil for this idea? I have read that potting soil is actually good for these starter trees vs typical inorganic mix they will eventually end up in. This helps mimic a bit more what it would be like if they were actually in the ground. But I’m concerned that straight potting soil will not drain enough. Maybe a layer of river rock and sprinkling some lava or perlite to keep it from compacting too much?

(Jonas Dupuich) #12

What an interesting approach - sounds like a good opportunity to experiment and let us know which mix works best.

Were I to go the this route, I’d consider using bonsai soil - a standard 30% akadama mix with pumice and/or lava.

(Frank Corrigan) #13

I am curious about drainage with your raised box. What did you have in mind ? I like the thought of a drainage layer and was wondering what other steps you have in mind. I have experimented with 60 percent garden soil/40 percent pumice in a raised bed that was in contact with the ground and it stayed way to wet, even with a drainage layer of 3/4 inch Lava. I ended up having to rescue my Japanese Black Pines from Root Rot after six months. I do live in an area with a lot of rain.


The floor of the box will be made using 2x6’s with 1/2"-1" gaps between each. Those will be covered by a 1/4" wire mesh. My thought then was to add a drainage layer over the wire. Above that is where I’m not quite as sure. I read somewhere that saplings and cuttings do better in regular potting soil until they mature more (may not be true or accurate, just recall having seen that somewhere). But definitely wouldn’t do 100% potting soil.

I had been tossing around 2 ideas, 1- add another smaller drainage layer above the river rocks, possible lava? Before then adding the potting soil as the top layer. Or 2- doing a potting soil/ lava/ and maybe a perlite mix all together above the river rocks. I guess a combination of the two could be a 3rd?

(Frank Corrigan) #15

I like the idea of using a second layer of drainage material. I feel that it prevents the smaller material from just flowing through and plugging the larger drainage rock. The drainage layers do not need to be very deep. Perhaps even one or two layers of each size. you might consider the following approach. 2x6 with 1/2 inch gaps. Layer of 3/4 inch drainage, covered by layer of 3/8 inch drainage. Then place the soil mix you prefer. If you use potting soil then an additional layer of drainage say 1/4 inch may be adviseable. Whatever you decide, be sure and update us on the progress.