Hi, what do you think about sowing maples seeds in trays and let them all the winter outdoor. I've protected mines from the mices and birds with plastic fence but I am afraid this will not be enough. I live in the french alps at 1100m and there is a lot of snow in winter. I am afraid that melting snow in spring will cause rotting problems. Will it be better to stock the trays in a sheltered place, and water them sometimes? I have a lot of trays thxs
If the trays are free draining, I don't see a problem with melting snow. Many of the Asian species come from mountainous areas and are adapted to snow in winter, so as long as the melting snow can easily drain away the seeds should be fine.
I agree. Free draining mix is the key: some like to put sand in germinating mix, but this will risk to stay wet, once the snow starts to melt. This said, the snow will serve to protect the seeds from unusual cold, and keep the temperature stable. I would consider it more of a positive than a negative.
Free draining is a must, but also consider the surface the trays are placed on - putting them on a flat surface will still lead the the trays waterlogging. I tend to put my trays on gravel or a a row of wooden batons to raise them slightly.
And what do you do to avoid damping off? I'm not a novice with seedlings but till now I was using refrigerator's stratification technique and pumice for sowing seeds. This year I harvested so many seeds. I can't use this technique and I'm using pine bark mixed with compost. (I have put large pieces of pine bark at the bottom of the trays to favour drainage) And finally I covered seeds with composted needles of pine
I've never suffered from damping off in maple seedlings grown outdoors. I put sand and grit on top of the soil, don't know if that helps? I also prefer pots to trays as I find trays are too shallow. I usually use 20cm diameter pots and fill them up to 60-70% of the height with potting mix, approximately 100mm depth of soil. I stand the pots on heavy concrete slabs, I feel that being in direct contact with the ground helps to regulate temperature and insulate the pots from dramatic swings in temperature. For example these images may give some clues to how I do it. They were sown outside in autumn 2009 and endured the coldest UK winter since the 1970's with plenty of snow, photo's taken early May 2010:
I don't use usual trays for my seedlings. I've bought plastic mason throughs of 10L which are very resistant and inexpensive. And I have drilled holes in the bottom for drainage and holes in the upper border to fix the plastic fence. I also use the throughs as culture pot for bonsai, it is very useful.
@Sébastien, last year I put lots of seeds in trays outside from november 2021. The soil I made was a mix of compost + bark + perlite. Next time I think over Winter i put a mesh on top of the trays because a squirrel that kept coming and digging... In winter: Seedlings started to come out here end of March here, and by end of April I have lots of them come out. I've scattered the seeds like that: and I didn't notice any difference about keeping wings vs removing them. Good luck with your growing!
Those are brilliant, Seb, great job. I'm sure they'll last much, much longer than the trays, which start to fall apart after a couple of years use. Personally the only issues I've had with trays being too shallow is when it comes time to separate the seedlings into small pots (godets). Roots tend to travel along the bottom of the trays, and get tangled. But I've always felt as though shallow is better than deep, to avoid wet earth underneath. I've had plenty of problems with damping off, which I seem to recall is botrytis? You have to spray (with copper, or a proprietary fungicide. I use the former) prophylactically, otherwise by the time you notice the problem, it's too late. As I am, um, rather Catholic about the process, I've lost entire trays of seedlings. It happened last year with a crop of A. monspessulanum, up very early and do in a cold frame.
@ChrisUk good job, you have had so many seedlings. I hope I will have same success with mine. I even noticed little pines on your pictures. What kind of pine do you grow? I'm also mad about sowing pines. @emery damping off is caused by many fungus like pythium or botrytis and some bacterias. I did'nt know that copper is effective. I have some conventional fungicides (propamocarb)and usually I don't like to use it. But sometimes (and damping off is an exception) it is necessary.
Pythium is a water-based root rot, and should only occur when your medium is too wet. I don't know that copper would help against it. Ont the other hand, botrytis or bacterial blights are usually very treatable with copper, it is certainly one of the most recommended solutions for the former. My point was, if you don't spray in advance before any possible symptoms, an attack will wipe you out. (With apologies to anyone I offended with the attempt at humor...)
That was the second year I grew small pines from seeds. I got seeds of Japanese Red Pine (Pinus Densiflora), Japanese Black Pine (Pinus Thunbergii) and Japanese White Pine (Pinus Parviflora). * None of the White pines came out... :( * Lots of the Red and Black pines came out. They all survived the extreme hot weather this summer, unlike many of the japanese maples seedlings... Oh also, for the japanese maples seeds, before putting them into the soil, I sprayed them with a solution of water and hydrogen peroxide (just in case there's fungus)
We generally collect many young seedlings after they have sprouted in early spring. A couple of specimens in particular ( ksagyama and Atrolinears) will have 5 -10 young seedlings coming up. The seeds come down off the trees in the fall after we have done all our winterizing and then the remaining few that have not blown away or picked up by birds come to life. Wind, rain, snow and freezing temps are all hazards that the strongest ( or luckiest) survive to become young trees.
@ChrisUk Pinus parviflora produces many seeds which are empty and unfertile. The seeds of white pines need minimum 3 month of cold stratification and they can take 2 years for coming out (like Pinus cembra, Pinus flexilis, Pinus koraiensis...)
Salut Sébastien, Perhaps you already know, but J. white pines used for bonsai are, most of the time, grafted on J. black pine. It seems they're stronger when grafted. The method you're using is very similar to mine, except that I use aluminium trays for frozen food (cheap!). The last ones I bought are about 5 cm high, which is well enough for seedlings. I add a layer of sand on top of the free-draining mix (mostly composted pine bark) and place the seeds on the sand, then I cover them with another layer of sand. Of couse, I make holes in the bottom, and leave the trays outside. The winters here are much milder than in St Jean de Sixt, but as Otto put it, the ones that survive are the strongest. On these photos (Jan. 2021), there was not much mix, but with the rain, the sand gets under the surface. These seeds were stratified in the fridge for about 3 months before (aquarium sand + a bit of sphagnum moss), but I had about the same result with seeds that I kept outside : April. Some didn't germinate, it depends where the seeds come from : I usually repot some of them when they have two or 4 leaves (not cotyledons), and leave the rest in the tray.
Thanks @Sébastien , I didn't know that! They are still in the tray so maybe they will come up next spring (unless they've been fried during the summer)
@ChrisUk I hope they will come up next spring. With pines from the "strobus" section, you have to be patient. Fortunately the seeds are very resistant (if not eaten by rodents, squirrels or birds). I've sown seeds of Pinus albicaulis (wich is a rare pine of the western US) and they had taken 2 years to come up (I was so anxious with those seeds, because they were so difficult to obtain). @AlainK I notice that you are using the same plastic fence than me. So I concluded that it is suficient to stop mices and other birds from eating my precious seeds. I had used composted pine needles to cover my seeds. I hope it don't will provide too moisture. Sand looks a better alternative. And for all who loves sowing maples I have this document which is a version corrected by me of the Dr Reno's book "Seed Germination Theory and Practice"
