I have this project over time to settle the big container ( 23 inches in diameter, at waist level )I have in the middle of my little garden and put a maple in it that would go upright first and then spread out so that we could walk under it ) Do you think it could be done ? What cultivars would be most adapted ? Thanks
Off hand I'd say a japonicum, but the width of the container sounds a bit small for something you want to get fairly large. Mine tend to grow upright and then spread, and the larger leaves make for a nice feeling to walk under. I have aconitifolium where I walk under it, but it is in the ground and larger than what you would get in a container. It is now about 10 or 12 years old. I have seen fairly large maples in containers that size at the local nursery. David
I'm not sure how much color you can expect from your maples in the fall there, but the japonica offer great color usually. Other possibilities that I really like, and might do well in a container waist high, are the thread leaf maples. I have a Koto no Ito in the ground that is taller than me at 10 years and absolutely stunning. It would need more attention for pruning--they get pretty wide but remain more dense and 'bushy.' I'm still leaning towards japonicum for you, and there are many choices.
The main problem I see would be its exposition to the South in summer. The weather here could be compared to that in UK. Do you think it would take sun alright ? for I read semi shade would be best.
My first thought after reading the initial post was Acer palmatum 'Omure yama'. It is said to grow upright at first, and then begin to grow outward with pendulous branches. The best picture showing this habit is in one of the Vertrees books, possibly the pocket guide. Though as jacquot said, the container size could limit eventual growth, and it would surely take a while for a grand, weeping specimen to develop to the size desired. Japonica are indeed a good choice for outward growth and great fall color.
Most any willowy upright Maple such as Sherwood Flame, even Burgundy Lace, would make an ideal Maple for having as a showpiece large container plant that can be easily be maneuvered under when tree gets some size and age to it. Omureyama is a very good selection but the trouble with this Maple is it is so hard to find the exact same plant as shown in the Vertrees second edition book of J.D.'s fine plant as pictured from his Roseburg garden. We have to keep in mind that for the Maples that cascade in order to maneuver under them then either we have to force these trees to grow taller or we prune out much of the cascading branches in order to be able to walk under them. An upright dissectum such as Seiryu might be a better choice once the tree is of mature age. Although some of the red atropurpureum dissectums can also trained to grow upright, create a round head with some cascade of the outward branches but for a container grown tree we will have to have some real patience and time to eventually get our desired result from a dissectum. [A word of caution is that a red or green dissectum once they reach a certain size or certain age will become less vigorous growing trees over time. This can cause some real havoc later with any internal and external disease issues once the trees slow down their growth rate. What happens is that the disease issues become much more noticeable and twig and branch dieback issues more frequent. I was mentored that there is a time line for how long we can keep a typical dissectum as a viable container tree and from what I've seen once these trees slow down in their growth rate it is very hard to correct and even live with, tolerate, a disease issue once this rate of growth happens. Think of it like a cancer that once the tumor is seen, it will only expand and infect other areas of the tree until the ultimate demise of the tree is inevitable. In some of the weeping cultivars this is a natural condition that once the tree is mature in the ground or grown as a long term in a container, its life cycle is on the downward slope for time.] Most any of the Japonicum aconitifoliums will naturally grow upright at first and then grow wider. Some of the very best and least fussy long term container trees I've seen were Aconitifolium. Long term here meaning can be kept in a large container for many years. I've seen some Maiku jaku that were 50 year old container trees. Hard to do this for that long of time with the palmatum types. The closely related Shirasawanum can also be kept as container plants for long periods of time as well. Many of the willowy upright growing Trident Maples can be grown as long term container trees without too much trouble as compared to several of the palmatum type trees. Jim
Thanks Jim and Praieriestyle Kind of you to develop such rich answers. I read Burgundy Lace won't stand full sun, so that may be a problem. The best combination I find as for personal taste and requirements is Sherwood Flame but Vertrees doesn't list it among varieties grown in containers though. I'll ask my nurseryman about what he thinks would be best between Sherwood and Aconitifolium for I like them both. I like multiple trunks.
'Trompenburg' is another that has the upright at first growth, followed later by spreading almost horizontal branches, should work well in a situation like this. Nice structure, good colour, great leaf shape and does well in a large container in full sun here in the UK. (Sherwood Flame and Aconitifolium are good choices too!)
How does one accomplish root pruning and soil replenishment when the containers are huge? Even 8-10 yr old plants, if they are robust, will crowd a large container in a few years. It is quite a project to extricate, prune and re-pot. Anyone have experience performing this maintenance on trees in containers the size Fabrice describes?
Sherwood Flame and Burgundy Lace are directly related. Your intensity of light will not be as intense or hot as ours is and if you look around in this forum you will see a Sherwood Flame of ours that really gets no afternoon sun protection at all. It is not the open sun you have to be more concerned of, it is the hot afternoon winds, of which the misses home does provide some wind protection for her Maple. Generally it is good idea, prudent in some growing areas, to increase the size of the container every seven to ten years. When we take a Maple currently being grown in a 36" box and place it in a 48" box with new soil we can leave this tree in the new and larger sized box for upwards of 15 years, depending on the Maple and overall shape and size of the tree we desire. Adding in new soil every five years or so is not a problem and the tree does not have to be lifted out of the container, although I've done it even with Maples in 60" boxes. An old trick I learned years ago is that we can force the trees to have natural air pruning of the roots if we do not place the boxes on solid ground. Place a few bricks on the ground and then place the box on top of the bricks and from then on there is no need to lift the tree out of the box just to prune the roots. I am not fond of pruning roots anyway, unless we are forcing the tree to live in a root constrained area for many years of which we want the tree to scale down in size. Even the then 40 year old Ima deshojo, we had in the nursery in a 50 gallon concrete horse trough on blocks, for 30 years was never lifted out to prune the roots. Jim
Jim, I'm trying to understand this. I live in a very climate where I have to move most of my containers into my unheated garage the winter. Are you saying that the larger containers in say a zone 7 or 6 environment would self prune in the winter if left outside and elevated? I'm not sure if you're writing about a milder climate like in northern France. This is a very interesting method. I've been fortunate to rehome many of my maples into the ground, but will always have some larger container trees, too, and have had varied experience overwintering if left outside. David
Perhaps I was mistaken but I had the impression that the Maple to be grown outdoors in France was to be left outdoors and not indoor protected during the Winter. I realize that for some of the palmatum type Maples that it may be resourceful to place them in protected areas during the colder months in areas that are subjected to prolonged periods of cold but what do we gain from this approach if our ultimate objective is to plant these trees in the ground. For young and juvenile trees left in let's say five or seven gallon containers we do not have the same issues with portability that we would have with trees in 24" boxes or larger in size. I am not trying to be facetious but good luck moving a 48" box into a garage for the Winter. Even a forklift might be challenged to lift and move a 48" box with a decent sized tree in it into a garage or enclosed protected area. The berm approach may even be a better way to go as I've seen it done on a grand scale at Toichi Domoto's nursery in Hayward. Whereby the large boxes were placed in a berm, surrounded on three sides with banks of mounded soil to Winter and Summer wind protect them. Container growing is not for everyone. Small container growing is one thing but to place a juvenile to close to mature aged tree in a large container requires some long term thought as to what we want from those plants. Years ago I bought a significant collection of Reticulata and Retic- hybrid Camellias. All 25 of them had been in a 15 gallon container way too long in my mind, so I went out and bought twenty five 32 gallon trash cans, cut four rectangular shaped drainage holes near the base of the cans and then proceeded to transplant every Camellia into those cans and have not looked back since. Yes, in time some of those old Camellias that were rescued were planted in the ground, albeit not all at my location but at the time of purchase I was looking at trees that were potbound, starting to look distressed and felt it was my duty to try to save them as best as I could. Well, only a couple of them have perished since twenty years later. A long while back we had a discussion in theMaple forum in regards to some newly available, portable and elevated plant containers with pedestal feet that were not only portable, can be moved with relative ease but were in my mind better than the wooden (cedar) boxes I was much more familiar with in the nursery as well as at my home and elsewhere. The trouble with the wooden boxes is that they do not hold up well after years of use. After about seven to ten years gaps in the wood sidings start to develop and with that a noticeable loss of soil can be a problem each time we hose water. Plugging up those gaps can be achieved but even in time our renovation can deteriorate and we end up having the same problem all over. If we lose soil we also lose water and thus a good drink of water during the Summer may all go to waste as in some cases due to those gaps more water is wasted than is applied to the roots. Then after a few years of having a Maple in let's say a 24" or 30" box and we decide to move it, I can pretty much tell you that when we lift or drag that box we are going to tear away the bottom boards from underneath that box and wish we had never attempted to move that box. The nice thing about placing the wooden boxes on top of bricks is that the bottom of the boxes do not rot out so easily, even upon super saturation from long term hose watering. The bottom boards stay pretty much intact. If the boards stay intact we lose less soil, keep more water in the root zone and will lesson the amount of stress upon that tree. The plastic boxes, in 24", 30" and 36" up to 48" as I remember it, provide a container that can be useful for a number of years, unlike the wooden boxes that do deteriorate over time. So, if we want to think in terms of a large container of which the tree is to be left in that container for a long period of time, it may be better to place the tree in a structure that does not deteriorate and with this in mind those large sized plastic boxes still are a better long term planter than any current day wooden box will be. Yes, we can get some air pruning of the roots during the Winter months but we also have to keep in mind we do not have a lot of root growth during this period. Some people feel that we have no root initiation at all but in trials whereby bare root trees have been heeled in the ground or into sand or humus, when we lift the tree out of that soil medium we can see new shoot growth that has developed on those roots but not a lot of it until the soil temperatures get above and are sustained at temperatures right at or above freezing. I've written before in a once thriving and well regarded, almost defunct now UBC forum of some of the parameters of container growing in which there were a number of different issues at play that may force us to grow those plants in a variety of ways: grown in ground or grown in containers outdoors, grown in grown or grown in containers indoors, grown in ground or in containers in a greenhouse or even in a well lighted atrium. We have the ability to do the same with a variety of Maples as long as we have a notion of what we want from those plants. I can say this that once we decide to leave a good sized Maple outdoors in a cold climate in a permanent large container, that either we let the tree better adapt to its location over time or we can try to harbor it from the cold but if we choose the latter portability and area constraints may be a problem. Jim
In this whole thought of the freeze, I still do not understand if the trees know they are in the ground or in a container when it freezes. The reason I say this is the fact that when it "freezes" where I live, the ground freezes just as solid as the soil freezes in the countainer. Both are just as frozen. now when I did bonsai and had large trees in small containers i di suffer issues but bonsai trees have issues with most seasons. I have now 800 japanese maples in containers and I have not seen problems from the trees being completely frozen but what I have had issues with is frost damage in the delicate varieties. This damage occurs late in fall when a tree does not loose it leaves before a big frost/freeze and also in spring when trees open up too soon and get hit by a big frost/freeze. The one thing I saw with bonsai was that by keeping a tree dwarfed by cutting its root system, it makes the tree at risk for many problems. where if you keep a tree in a container larger than its root system the problems greatly reduced. In a nut shell, I have had many container trees which have been frozen blocks and each year they come back great.
I think the primary difference between the evaluation of a frozen container and frozen ground is has to focus on a couple of factors. One, a tree in the ground, after "X" number of years will have a root system larger than that of a container maple. For "X" number of years post-planting, the root system of the in-ground tree would be small enough that the two situations would be somewhat analogous. At the point the root system is larger, then we obviously have more roots to work with. The second factor would be the ability of the ground or the top layer of earth to insulate the the roots below from prolonged or progressively falling ambient or windchill temperatures. The issue with the potted maple, depending on the size, material and location of the plant, is that the ability of the container to insulate the maple is limited or finite. If the pot is exposed to any degree of temperatures in the "killing" zone for any length of time, the temperature of the pot will drop until it reaches the ambient temperature. One has more time for the same maple in the ground depending on size, age, etc. A maple in dry potting medium or dry conditions will not be as resistant to freezing as the water, and subsequently the presence of snow on the ground, will further insulate the roots. If we assume that allowing our pots to freeze means some degree of bottom-kill, then the question is how much of the bottom can we lose before we lose the top and then the plant. The other side of the coin is the top of the plant, and how much cold or freezing the wood can survive and still be viable. Along the majority of the west cost, there seems to be little risk of overwintering maples out of doors and allowing some freezing of the pots to occur. Sometimes the stress on the plant will allow it to succumb to other diseases and conditions, but rarely, if ever, will we lose a maple to temperature alone---that is until the "big" freeze comes, and then we learn the hard lesson of being at the mercy of mother nature.
Yes, as Galt says there is a big difference between frozen ground and a frozen container. -10°C (14°F in USA) is generally considered the magic number for root death in containerised Japanese maples. Exposure to temperatures below this for any length of time will surely kill a container tree (the larger the container, the longer it might hold out) while the in-ground trees have their roots nicely insulated by mother Earth, only the top few inches exposed to the killing zone. In the west coast of North America, UK, and Northern France we are lucky enough not to face these temperatures normally, and so our container maples generally survive the winter. Those maple people in zones 5, 6 and 7 are not so lucky; hopefully we won't join them in that "big freeze" any time soon. My container maples often freeze solid in the winter and seem to suffer no ill effects, with no apparent difference between mild (say -3C) and harsh (-10C) winters. Obviously the white feeder roots are destroyed by these temperatures but it seems to me that their destruction is a natural part of winter, and the storage roots always seem to be sufficiently lignified to survive. Almost like a reflection of the top growth, where woody branches survive the winter but soft, fleshy, (over-fertilized) growth generally fails.
can I ask then, if the temp than goes down to around 0°F for a period of time then a in the ground would start to suffer similar to the tree in a pot at the higher temperature? My understanding of soil is it is a very poor insulator add to that japanese maple trees tend to have shallow roots so this is why I ask. As noted, I live in a warm zone so I have little chance of seeing these low temps, but i do get people wh come from the neighboring hills and they do see temps this low and lower so it is nice to have knowledge about cold.
0°F doesn't seem to be a problem for Japanese maples in the ground. The lower limit seems to be somewhere near -20°F (−28.9 °C ). (From experience of people who live in colder climates than myself).
We normally never have -10° C temps here in Northern France, very cold winters happen but don't last long. I am just one mile from the sea, so it helps. However I did protect the maples I have in containers this past winter in bubble wrap. Better safe than sorry.
