Eastern White Pine repotting

I collected some pines 10-12 years ago, they winter in the ground without pots annually as they break, so I see the roots every year and they look just as they shouldn't every year, large thick white roots at the bottom of the pot.  This winter I was reading about inorganic soil and decided to try it, I used river stones black lava and pine bark.  I followed what I do every spring and prune the roots when I put it back in the pot, I am now reading this is not right but in that they are being taken from the ground it seemed right and they always seemed okay with it, candles extened with good growth.  I now read that it is not good to bare root a pine, should probably have read more specifioc to pine because I bare rooted one!  (fools eh?)  I have lost the Mycorrhizae, Question one is should I take some of the soil from another pine and put it on the roots or just leave it?  The second question, is the particle size too large? I used what went through a 1/2" but was retained by a 1/4" mesh, now the pine bark and lava is a bit bigger than the river stone.  The third pic is of Turface (I can get similar sized bark), Lava and river stone all about the same size. I could also go in between the two with bark, lava and stone.  If I should change this when? wait till next year or do it when the needles have hardened?  Thanks


   

Dear Oleg6,

You can actually purchase mycorrhizal products these days at garden centers and the internet. Pines specifically rely on Rizopogon ectomycorrhizae (ECM). If you go to a garden center or purchase on the internet, make sure the product contains Rizopogon spores such as Rhizopogon amylpogon, Rhizopogon fulvigleba, Rhizopogon rubescens, Rhizopogon villosuli, etc.

I don't specifically work with Pines or Rhizopogon, because I grow mostly maples, ficus and medicinal herbs. I use specifically endomychorrizae of the Glomus variety to encourage healthy root structure in new seedlings and rooted clones that would otherwise need to be grafted to hardier root stock.

Good luck with your pines.

Best regards,
Geoline

Thank you for the advice, I recently found mycorrhizal on a website, treehelp.com that sells locally here they said each was specific to the type of tree, but your post seems to really nail down exactly what I'm looking for.
Thanks again.
Chris

I have some knowledge of ECT fungi is because it is used in pine reforestation projects. Rhizopogon has been used to reforest pines in cleared land to help improve water quality for nearby communities. Cleared land involves killing off all other plants and basically sterilizing the soil so that the pines do not have to compete with other flora. Bonsai soil used for pines are mimic sterilized cleared land. Rhizopogon, in theory should work well with pines receiving some nutrients in bonsai soil the same way it works in clear land reforestation projects.

Pines innoculated with ECT Pisolithus tinctorius is used to reclaim and reforest highly toxic soils in mineland areas. Pisolithus tinctorius also happens to be a more common biozone additive in commercial organic gardening products (like Jobe's Organics All Purpose Granular Fertilizer which is relatively cheap and ubiquitous at garden centers). I guess the idea here is that it may be more tolerant of the harsh chemicals we use on our lawns.

I repotted a severely root bound white pine last spring. Some of the top had died back from what i assume was being too dry in the center of the root ball. At the time i removed about 60 percent of the root ball and bare rooted it. I used oil dry, similar to turface, grit that was the same size, and some bark that was a bit larger. The tree did amazing last summer, didn't seem to even notice what happened, and right now candles are starting to form and appear to be nice and healthy. Bit on the late side but that said so is everything else this year. I've found that these pines grow roots like crazy. As for the size of your mix, compared to mine its much larger. Since you repot every year anyways, i would suggest waiting until next year if you were change soil size. I also wouldn't worry too much about the fungus if you use a liquid fertilizer the tree should still be getting what it needs for the most part, if i remember correctly the tree should also have new fungus colonize on its roots over time

Chadley is correct.

I'm not sure if the mycorrhizal relationship is necessary in such a confined pot root zone space, as the fungi is competing for space with the tree's roots. Although, in harsh climates, mycorrhizae and certain cyano bacteria have been known to partner with pine to grow on the edge of cliffs where there is virtually no soil. The mycorrhizae role is to break down available nutrients in the form a plant can use, crowd out pathogenic microorganisms, provide more root zone mass to find nutrients and water for the tree. For bonsai confined in shallow pots, you need take on the role of the mycorrhizae by delivering its nutrients in easy intake form and getting rid of pathogens and competing flora. Repotting , soil changing and root trimming will destroy the mycorrhizal community. (I think I had this discussion with IBC mycologist Nina Shishkoff almost 20 years ago.)

Otherwise, the fungi is good for trees with a weak root structure (ie, seedlings from an acer palmatum cultivar developed in another region) or a root system that cannot tolerate foreign soil conditions. So for developing root mass on pre-bonsai seedlings and clones, the fungi is awesome stuff.

Thanks again,

I might try it, what I found was only 10 bucks and it said it would do 3 smaller potted trees, which is what I have. I was thinking it couldn't hurt. Although I generally repot in the spring, current advice I've read is to do it later, after the needles have hardened. I was also thinking of what taking them out of the pots would be like in the fall with only one years root growth, that the weight of the lava and stone might fall apart tearing the roots. I bought some cheap Tupperware containers the right size, I was thinking of drilling holes in the bottom and trying to transfer them before much root growth had taken place. The idea being that they could spend several years undisturbed to form a strong root ball, by covering the top with cloth I could bury the hole tub deep in the ground then covering with leaves. Though I have also just read of someone quite experienced with establish trees loosing some by changing time he repotted, as I'm suggesting. A tough choice.

Generally pines are not repotted every year, and with your planting them in the ground in the fall and digging them up in the spring you are disturbing the roots twice a year. Your trees are not likely to survive this long term. I would suggest that you keep them in their summer pots, and simply bury the pots in the ground outside in autumn, without disturbing the roots. Then dig them up in spring. If your summer pots are not freeze tolerant, still do the same, they will break over winter. During the winter purchase higher quality freeze tolerant pots. Transplant them in the spring and try to not transplant again for at least three summers of undisturbed root growth.

Your potting mix is fine, less than 1/2 inch is fine enough, especially for young trees. No need to change it.

Eastern white pines are nice in that their roots tolerate wet winters better than most western and mountain species of pine. They are nice and hardy and easy to grow for those of us east of the Mississippi. Your first job is to let the seedlings develop some initial branching and volume, so that when it is time to style them, you will have choices. Fertilize them, and give them sun this summer and next summer. Maybe by the 3rd summer you will have enough branches to have some choices available for styling.

I don't worry much about mycorrhizae - if you did not treat your tree with a fungicide when you repotted you likely still have some small amount of mycorrhizae still inhabiting the bark of your roots. It will colonize your pots quick enough. If you have white pines growing in the ground within a mile of you, spores are in the air of locally appropriate mycorrhizal species.

When it is time to get styling advice, many will tell you eastern white pine P. strobus is not good for bonsai. You will also get people like me who will encourage you to try it anyway. Jim Doyle, Marty Schmallenburg, and a few others have turned out very nice national exhibit quality P. strobus, so they can be done. It is a species with some less than ideal growth habits, but as you become more familiar with how this species grows, you will figure out how to deal with the growth habits. I have not got it figured out yet, but some day I hope to. I will share when I know. Unless someone like Jim Doyle tells you different, by and large use the same general techniques one would use for Japanese White pine, Pinus parvifolia. Do not do the early summer candle pruning that one does for Japanese Black Pines. P. thunbergii, this will not give good results, potentially kill your tree if repeated too often.

Plenty of time to research styling techniques. For now, let this tree grow for one full 12 month year without repotting, wiring, pruning, or "pinching". Just let it grow to get healthy and vigorous.

Looking good.
Leo

Thanks a lot Leo.

Chris