Not in the realm of an older plant.....but young plants 1G-3G. Granted I'm sure it may depend on the grower, what container soil is being used, watering schedule, etc. Presuming the understock is all the same - Acer Palmatum, what dictates or drives how the root system is on a JM plant. I've received rootstock of all different variations. Some with 2 thicker roots and fine roots. Some others that I wasn't crazed about and it didn't have many fine roots but just a handful of -thicker roots- (this was a small, 1G in very sandy dense container mix). In other plants, not fine roots but just a smaller mass handful of toothpick thickness roots. I did not bare root my 25G's. Flare was ontop of the pot plug so for these, I just scarified the sides of the soil and planted them as I did not want to chance killing my $$$$ acquisitions.
I am unsure of just what your question is, but roots must be kept moist but yet get air (oxygen) to live and grow. IOW, roots will be poor in a dense soil or one with little air-filled porosity. The smaller the air spaces between soil particles, the more it will retain water and tend to drown the roots = low air filled porosity. Interestingly, the interface between the pot wall and soil that will compact has a relatively higher air filled porosity --> roots tend to grow in this interface instead of the bulk of the soil. Roots grow from the tips. Hair roots, that are the extension of the cell walls of epidermal cells a few millimeters behind the top are responsible for the bulk of water and mineral uptake. The rest of the root is little more than plumbing. If the growing tip is deflected by a hard particle, it tends to branch at the bend --> hard particles in the soil will cause the root growth to branch. Removing the growing tip or root pruning causes root branching closer to the trunk. Root tips dying by desiccation or air pruning has the same effect. Of course, root pruning when new growth is extending is not good as extending that new growth requires a lot of water. Unbalanced roots can result from bad luck and/or because of an imbalance in the foliage distribution. Carbohydrates and auxin produce by the foliage and buds flows down the tree in the inner bark (phloem) analogous to how a thick syrup would flow if simply poured onto the top of the tree. IOW, a branch with lots of foliage tends to produce a big root (which in turn tends to supply more water and minerals to that same branch, over time. This can be reversed by partially or completely removing the root and/or reducing the corresponding foliage above. Note that one can simply prune that one root if the tree is ground planted. If you are at a nursery inspecting potted specimens, look for trees grown in composted bark chips instead of the usual garden soil as they will nave more/healthier roots (ibid). Anything like answers/opinions you were looking for?
Yes, just needed someone to break it more down in granular for my Wiki. Regarding the sandy soil.....most of my JM's are mail order and fairly decent (as I cull out the good JM mail orders vs others) generally in bark/perlite or bark/pumice mix. On the sandy soil....I was committed. I drove 4 1/2 hrs to this place. I left with what I went there for and an empty trailer on my tow hitch as this JM source just had poor stock if not poor container mix habits.... It did rain heavy the other day before I visited so the pot was heavy ....but when I got home, to see what I was working with, it was a poor root system due to the soil medium it was planted in. Just took order another JM mailorder...and as always , such a huge difference in roots systems I see sometimes.
All rootstock is not the same. Because it's grown from seed, (in the case of Acer palmatum), there is a vast variation. Some is dwarfing, some it sick, some is vigorous, some is healthy but slow growing early... every variation you can imagine. All of this effects how the top (scion) will perform as a graft, regardless of substrate and nutrition. Everything 0soyoung says is true, but the fact remains that plants are like individuals, and rootstock is, erm, plants. Another thing that can make root growth uneven is black nursery pots heating on one side. I have often found maples growing towards the cool side of the pot. (Difficult to keep the pots in shade, as would be desirable.) The other thing comes from recent techniques of growing rootstock from pegged layering. This leads to uneven growth (towards the ground-side of the layer) and a large wound, which often dies upwards, where the thick branch is cut. Commercially this procedure has the advantage of producing good caliber rootstock without the 2-3 years otherwise required, as well as allowing selection of vigorous stock; this is however largely outweighed by the disease problems, especially as the layers tend to be over-fertilized.
That is one helluva remark. Here I was thinking most independent nurseries are buying -bulk rootstock- from X supplier, just short of Acer Reds, I was thinking there would be some consistency amongst the trades. Right now , on a particular plant:cultivar I spent 10 hrs in total driving for it, I feel like I'm nursing the heck-ova out of it just to bring it in true form. It's leafed out and I can see potential.....when, hopefully in the next 2 years, I can get a good system on it. Is it possible that I can have crappy rootstock and it will never get vigor ....I'm only in year 2 of JM's. I gotta say.....I'm not really impressed with the understock size or roots. However, it has leafed already and I can see potential if this thing can get some Vigor growing down and up "found maples growing towards the cool side of the pot." I've noticed this on some JM's I have received - mainly the 3/5G formats. This wasn't on my radar. I actually thought it was staking but now that you post this, maybe this is it. It's like on particular spot of a *round perimeter* of the trunk, there are just no roots in one section
Unfortunately, yes. Maple rootstock is not like Apple (or other fruit) rootstock. These, understock is carefully trialed over years, and then reproduced by cloning. So the scion wood will always react in the same way for a specific rootstock, because it's genetically identical to the others in it's class (although of course there are choices of different rootstock you can use). Rootstock is the dirty little secret of the business. Maple rootstock is almost all seed-grown, with the exception of the pegged stock currently being produced. But since industry people know about the disadvantages of rooted cuttings (tendency to die after 5-10 years), seed grown is preferred. Which seed? Seed which germinates early and can be forced in a greenhouse. If an understock takes more than 3 years (upper limit) to be ready to use, it's not economical. So the seed comes from a thin-skinned green maple or maples. After all, we need 20-40K of these things. Because of the variability of A palmatum seedlings, any variation is possible. Of course "most" of them are vigorous maples, thin skinned or no. But their treated in the tunnel, lots of copper and pesticides, anti-mold or botrytis, EM if you're lucky, etc. Mostly they don't harden off sufficiently before use, which is why during a maple's first year out of the nursery, it's the understock that's more likely to have problems than the scion (with notable exceptions!) Some rootstock is already sick when it's being grafted. This is one reason why, as a consumer, you're often better buying a maple that another nursery has coddled along for 2-3 years post-liner; the stock has hardened off, the graft is healed, if it was doomed from the start, it already will have died. I usually buy liners, they sometimes die, and it is almost 100% of the time that the rootstock fails, not the top. But even then, there's no way to tell how the stock will perform for vigor. Big wholesale nurseries grow their own rootstock. The quantities are such that they can't spend much time with each plant. They sell to the smaller nurseries, often bare root. Best practice is to leave the stock in the liner container for a full year before grafting. That costs money. Throwing out stock that doesn't look great costs money, and small nurseries are quite low margin businesses. It would make loads of sense to produce palmatum rootstock by tissue culture, but the industry (unlike apples) just isn't large enough to justify the research costs, when cheap and "acceptable" stock is available by other methods. Some Red or Freeman's Maples, that are very popular, are produced by tissue culture, as it's difficult to get consistent results through grafts. Most red-leaved cultivars used to be grafted on red-leaved understock, because there is some evidence of genetic transfer across the graft, and it was always believed these kept their color better. (Also, of course the stem color matched better!) The practice has been practically abandoned, though. HTH, -E
