Japanese white pine (Pinus parviflora) seedlings advice.

[Ykr]

Hello!
In the fall I went crazy buying and collecting different tree seeds for bonsais and to grow full size. I was at a nursery that had 3 large grafted JWP with pine cones on them. I did not know anything about the tree at the time (still very new to the hobby, and it's my first year growing trees from seed), but the trees were beautiful and I asked the nursery employee if I could have the pine cones and she said sure. When I did some research I realized how rare these seeds are but apparently in that situation the seeds are probably not viable so it killed my excitement. I did decide to go ahead in soaking and planting them because I had some extra space. I got around 45 seeds that sank and the rest floated. I planted most up in 2 mini greenhouses in seed starting mix and left them on my porch with the rest of my mini greenhouses to cold stratify (added a photo of the mini greenhouse). I had a few leftover that I just stuck in the fridge and a couple weeks ago I decided to check if there is any life to them and just stuck a couple in a tiny pot on a heat mat and to my surprise they sprouted (see below). At this point should I bring the greenhouses in and let them get a head start on the season (zone 6) or is it too early and just let them do their thing outside. And once they have a few sets of needles how big of a pot should I put them in and what kind of soil has the most success for them? I would like to keep a few for bonsai and a couple for in ground planting.

I do not intend on keeping a lot of them if they sprout. I am looking for a new job so I am likely to relocate and will probably not have space for all the trees and seedlings. So if anyone lives in East Tennessee or SW Virginia and has any interest in JWP seedlings I would be more than happy to give some away (of course if the rest sprout knowing my luck the only two I tested were the only viable ones). I know they could have cross pollinated with something else so can't guarantee purity or anything like that, but I do not plan on charging anything for them passing on the kindness since the nursery employee let me have them. Also have different varieties of trees good for bonsais in the other mini greenhouses, any extras of those I would be more than happy to give away as well.

Any advice on growing these beautiful trees or seedlings in general is appreciated.

Thank you!

 

[Wulfskaar]

Welcome!

I've been growing from seeds since 2020, so I've learned a little bit about that.

I would probably do what worked, which is putting them over the heating pad, but there's nothing wrong with letting nature take it's course outside and letting them sprout when they are ready.

Wait until the first set of real leaves/needles has grown out before you can transfer the seedlings to larger pots. Many people use perlite and peat for growing out seedlings. Once you do that, just let them grow! They should be outside in fresh air and sun. Water when the soil starts drying out. Fertilize lightly until they get bigger.

Keep in mind, it will be years before any of those are bonsai, probably a decade or more.

 

[Wires_Guy_wires]

Do not keep them in the dome, please. Put a net over them, or some wire mesh, but the dome will cause moisture buildup and transpiration issues leading to certain death in most conifers.

 

[Ykr]

Welcome!

I've been growing from seeds since 2020, so I've learned a little bit about that.

I would probably do what worked, which is putting them over the heating pad, but there's nothing wrong with letting nature take it's course outside and letting them sprout when they are ready.

Wait until the first set of real leaves/needles has grown out before you can transfer the seedlings to larger pots. Many people use perlite and peat for growing out seedlings. Once you do that, just let them grow! They should be outside in fresh air and sun. Water when the soil starts drying out. Fertilize lightly until they get bigger.

Keep in mind, it will be years before any of those are bonsai, probably a decade or more.

Thank you for the advice! Any recommendation on the best fertilizer brand for tree seedlings?

Yeah I am in no rush to be honest, this is all just prep. Creating my own little collection of stock trees for the future. Keeping them in pots for years before I do anything with them. Some to bonsai and some to put in the ground. I enjoy watching things grow so it will be fun watching them get bigger for years to come.

Do not keep them in the dome, please. Put a net over them, or some wire mesh, but the dome will cause moisture buildup and transpiration issues leading to certain death in most conifers.

Ohh okay noted, I have Cedar of Lebanon seeds as well I will just take the dome off and cover them all up with the anti-mouse mesh I got to cover my American chestnuts (I know the odds are they won't live but I can't not give them a try).
Thank you

 

[Wulfskaar]

Thank you for the advice! Any recommendation on the best fertilizer brand for tree seedlings?

I'd probably wait until after the first growing season to fertilize seedlings. As far as what type, I'm not sure. I have used solid and liquid fish/seaweed and I honestly can't tell the difference, other than the liquid stuff is required more often.

Some species may like different fertilizers, so you might have to research specifics on that.

Enjoy growing your trees! I have found it to be very personally rewarding.

 

[Leo in N E Illinois]

As recommended by @Wulfskaar , it is best to keep JWP outdoors only. Sprouting indoors it is difficult to give bright enough light for normal growth. In addition, best growth is with a sharp day-night temperature change. Night should be 10 to 20 F cooler than daytime temps. This temp change allows the accumulation of sugars for growth. Indoors day and night tend to be close to same temperature. This means metabolism at night runs high consuming more sugars than a cooler night would have. This is why many tree species languish indoors even when light seems adequate.

Aditional note, JWP seed tend to be viable for only 18 months stored cool and dry in a refrigerator, meaning germination rate will drop below 50% after 18 months in a refrigerator. Germination rates drop more quickly if stored at room temp. (70 F or 20 C)

Another comment. with pines, ideal cultivars have short needs, deep green to blue green to blue in color. Blue in pines is due to a white waxy coating on the needles that leaves a "blue-ish" color. Wipe the wax off and the needle is green. In addition to to short deep colored needles an ideal cultivar will have straight needles without twisting. Many North American pines have needles that twist on their central axis, noticeable if you follow the lines of stomata on the undersurface of the needles. Twisting is unattractive in bonsai.

The reason the majority of JWP in North America are nurseries are grafted is that the majority of JWP from seed do not meet bonsai standards for attractive pines. They are often yellow-green rather than deep green or blue-green and the "blue" seedlings are very rare. Short needles are not the rule, and most from seed have twisting in their needles . So if you germinate 100 seeds, maybe a couple will be passible for bonsai as far as needle characteristics go. The named cultivars were selected from thousands of seedlings.

I am encouraging you to do grow JWP from seed. But I am also encouraging you to be selective as to which seedlings you grow on to larger plants. Somewhere around 2 year mark you should be able to cull out 90% of the seedlings as less than desirable for bonsai. Especially if you are looking for "blue" JWP you may need to raise hundreds of seedlings to get just a couple.

Interestingly, with JBP and JRP the percentage of seedlings from seed that seem acceptable for bonsai do seem to be higher. Near or over 50%. In part because the "blue" color sought after in JWP is simply not a possibility in JBP or JRP. These 2 species simply don't "do blue". Twisting in the needles is a flaw, and can be selected against.

 

[River's Edge]

the majority of JWP from seed do not meet bonsai standards for attractive pines. They are often yellow-green rather than deep green or blue-green and the "blue" seedlings are very rare

Interesting comment, I have noticed that the seedlings change colour ( deepen darker green first then later a bluish tinge) as they mature. The new growth is always a lighter almost yellow green. For example the batch of JWP seeds I germinated last year have dark green juvenile needles with a bluish tinge, the newest juvenile needles are yellow/ green. One of the other variable is cooler temperatures for the seedlings pushing new needles. I will be interested to see how the seed batches collected from a variety of sites in Japan compare or contrast in needle size, shape and colour development. The seeds I acquired come from three separate areas. Expect there should be some regional differences.
Selecting or acquiring established known cultivars is definitely the best route to ensure the needle size, structure and colour that one might prefer. Also interesting to note the variety of needle shape, size and colour on the JWP shown in Kokufu and Taken Ten that are wild collected trees as opposed to " cultivars" .

 

[tanlu]

I’ve been purchasing Mt Ishizuchi (Shikoku island) JWP seedlings from Julian Adams for years, and recently 3 other JWP seedlings (northern Honshu variety) from another vendor. All of the Ishizuchi JWP seedlings exhibited the typical gorgeous silvery, blue-green needles that are relatively straight and short when grown in bonsai soil. The northern Honshu JWP seedlings had dark green foliage and even shorter short and straight needles reminiscent of Zuisho. I’ve noticed that when grown in-ground, those needle differences start to show a little more, but certainly or not in a way that made them poor candidates for bonsai.

Now, the main risk of growing JWP from seed in North America (at least east of the Mississippi River is the chance of local EWP pollen, which could lead to much longer needles. Julian mentions this issue in his book on pines as have others on this forum. Some JWP seedlings might exhibit yellowish tinge in their foliage during dormancy, but that shouldn’t be considered a flaw since most conifers tend to do this when dormant.

Another reason to be concerned about EWP genes mixing with JWP is that EWP bark takes much longer to mature than that of JWP.