The title of this was supposed to be IN pots, not ON pots! I guess it would be kind of difficult to raise them on a pot. Ha.
Cathy

Hehehe!! Now that's a new method of growing trees - ON pots!
Cathy, the roots of every tree I've ever grown in a pot have quickly outgrown the pot, and I've had to plant the tree out. Unless you know bonsai, which includes root trimming along with branch trimming, you'd be unable to keep any tree in a pot indefinitely, unless the tree wasn't thriving, in which case, it'd eventually die in the pot.
You can use what they call "sleeves" over branches to protect cats - I've used small ones, and they were a lot of trouble. You could still clip small branches or individual leaves from the tree in the pot and use it to feed your cats in a cage.
You really need enough space to be able to plant your trees out. If I didn't have 5 1/2 acres of woods, I couldn't do it.
Sherry

There is really a lot of ground to cover for one post, but I'll try to cover at least some.

Some trees will do much better in pots than others, and different types of trees may require different techniques. The first thing you'll probably want to determine is how big the tree would normally grow. In general, trees that naturally grow large will make poor candidates for long-term growth in pots except in a bonsai situation. I won't go into bonsai except to say that you'll need to study up on it if you plan to use the techniques to control the size of your trees. Also trees with taproots (oaks, pawpaw, sassafras, etc) generally don't do well in pots. If you do want to grow a taproot-forming tree, use the deepest pot you reasonably can. Another way around the issue of growing large-variety trees in pots is to grow them as temporary specimens and replace them every few years. By the time you decide to replace them, they may be too potbound to plant out and you may have to resign yourself to throwing them out. I would have a hard time doing that, but it is an option.

A second consideration, which I see you are already aware of, is cold hardiness. A plants root system is the least cold tolerant part of the plant. You'll probably want to choose plants that are one or two full zones hardier than your area's hardiness zone. One way to minimize or even eliminate this concern is to bury the pot in the ground over winter or to place the pot on the ground and use mulch to form a mound that completely covers the pot. Using foam or insulated pots can add a little (half zone?) protection.

A third, and highly important, factor is soil type, drainage, and soil deterioration. I am going to try to find a link to a must read post from the Container Gardening Forum, and will link it below. Keep in mind that even with a really durable, high-quality soil, you'll still need to repot your tree every few years. As the tree grows, this task will become more and more of a challenge.

Watering and drainage are also important factors. The post that I will link below will give lots of info about drainage, but I'll reemphasize here that it's critical. The frequency of watering required will be determined by factors like environmental conditions, size and type of tree, soil drainage/capacity, and container size. Larger pots will hold more moisture and reduce the frequency of required waterings.

Well, I've just skimmed the surface of a few aspects involved with growing trees in containers, but, especailly with the link below, it's probably quite a bit to read. If you have any more questions (except about protecting your cats from being parasitized - which I haven't the foggiest idea about), please ask or even email me. I believe I can also answer any questions you have about Al's post. I was in the process of writing my own similar post when I stumbled upon his.

Here is a link that might be useful: Al's Post on Container Growing Media

There are few trees that cannot be grown in containers. Even those with reputed 'taproots' will do just fine if you learn some basics of container growing. The fact is, those tap-rooted trees lose that characteristic after a very short period of time, anyway, switching naturally to the more efficient (and shallow) fibrous root system.

The only bonsai techniques that you would have to learn (but not limited to bonsai by any means) are root pruning and top pruning. Both are quite easy and will help your trees have a long and prosperous life within the confines of a container. I root prune all of my houseplants, as well as woody plants in containers that don't happen to be bonsai.

3 gallon containers are certainly not very large, but only you can be the judge of whether or not your plants can remain in them for another season. Potting UP is easy, too.

Brandon mentions 'soil' type is highly important. In my opinion, it is THE most important factor in container culture. Do some research regarding building your own simple potting medium. The Container Forum is an excellent place to start.

By the way, most professional nursery mixes are composed almost entirely of aged bark fines. With a very few other amendments, you can make yourself a long lasting, fast-draining, porous medium that is sure to foster plants of nearly all kinds.

Rhizo, what you say about taproots just isn't true. Some trees partially or completely de-emphasize their taproot dominance as they mature, but many don't. I've seen trees with taproots larger around than me! Trees with taproots are, on average, more of a challenge to maintain in shallow pots than those that don't form large taproots.

Successfully growing naturally very large trees in pots long-term is going to require more than just occasionally chopping some roots and branches off. Bonsai is one method of approaching this. The artistic form part of bonsai would not be necessary to successfully grow such a tree, but many other aspects would be necessary to implement bonsai-ish technique. Chopping off a few roots and branches here and there is not bonsai at all and is not a reasonable strategy to maintain such a tree over a long period of time. Houseplants are totally a different story than woody plants.

I only visit the Conifer Forum occasionally, but the conversations I've seen there about container soil frequently center around the information in Al's thread. I linked the thread to a post there once only to find that it had been mentioned a few days before in a related thread on that forum.

I've grown a tulip tree and a hackberry in pots for a few years now. They seem to be doing fine and I haven't done anything special for them. I don't know how big the pots are though, but they are pretty big. I'll try to take a picture sometime and measure it. The only things I do is make sure they are watered well in the summer when it gets really hot and dry and, if I remember, I put extra mulch on top before winter.

I've also tried pawpaws and a sweet bay magnolia in pots, but they haven't survived. But then, I've put pawpaws out in the yard that haven't survived either.

I've been getting Tiger swallowtail eggs on the tulip tree the past 2-3 years too. But I haven't seen anything on the hackberry. There are many hackberrys growing wild around though - butterflies around here have plenty of other options rather than using my tree.

I don't usually bother with protecting many cats anymore, but if I would I would just cut off a few leaves or a small twig and put it in water someplace safe. I've done that with Tiger swallowtails.

My husband just reminded me that he's been putting fertilizer on them too.

Oh, and I have a hop tree in a pot also. That wasn't planned though, long story.

3-gallon seems awfully tiny to me. I have a number of 'trees' in pots in my yard...three citrus trees, a willow, ...but the pots are quite large. The willow has already grown its roots through and under the the pot. THAT didn't take long so I guess, technically, it is no longer IN the pot! ha ha ha (which is okay by me since the tree it is in front of is one hubby and I both don't particularly care for and have considered removing).

There are ways of trimming the roots along the edges of the pots so the plants don't become 'root bound' but I agree that soil and size of container are extremely important. I just recently transplanted my Mexican Lime into a larger pot because it had gotten too big for its previous pot.

I don't know if constantly pruning will help in keeping a plant down to a shrunken size or not. We have a so-called dwarf avocado that is humongous! ;P

Trisha,

I you want to try another pawpaw in your yard, either plant seeds and let them grow in place or try to get one in early spring and plant it before it starts budding out. Be very very very careful not to disturb the roots any more than necessary. Frequently pawpaws are grown by nurseries in bottomless pots so that the roots are air-pruned. Those are much more likely to survive than pawpaws grown in standard container and potbound.

My only comment would be for the most part shrubs and trees can be kept in very small containers if one uses proper techniques. But there is regular maintance involved. It's what I do. :-)

Clickable thumb

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Plant has a 4" diameter trunk and is about 3 foot tall.

I've had some species that develop a large tap like Red Bud and Pecan in containers. The taps were removed. After two-three years in a container they just kind of peter out. Branching was bad, die back occurred and I ending up tossing them.

randy

Brandon, I was trying to steer Cathy away from what could be an intimidating discussion of bonsai. That science/art form has little to do with the subject matter at hand. I'm sorry that I confused folks.

I have a handsome bonsai collection which includes some specimens that are getting somewhat 'long-in-the-tooth', so to speak, and am pretty familiar with the techniques. I've had lessons and have given lessons.

However, I also grow numerous containerized trees for decorative purposes. These are not subject to the 'rigors' of bonsai at all, other than very rudimentary root pruning and top pruning to maintain form and size. Pot sizes range from 28 to 36 inches.

The root pruning, done on an annual basis (for the most part) is essential for those plants just as it is for my bonsai, but done with much (much) less care, if you will. It is performed so that I can keep these trees in the same container year after year, with an ample allowance for healthy new root development. It's the new root growth that allows us to keep woody plants healthy in containers.

The non-bonsai root pruning of woody plants and most of my house plants are extremely similar procedures, and no reason not to be. The only thing that changes from plant to plant is how much to slice from the bottom and sides, as it depends somewhat on the plant family (as well as the shape of the container).

Cathy, I doubt that you could grow many tree species 'indefinitely' without learning to practice the constant renewal procedures of bonsai. But you can, with very little effort, enjoy them for several years. But not in three gallon pots.

I use for all of my containerized plants, a mix that I've adopted from two sources: bonsai culture and golf course greens. Don't laugh about the latter. The largely artificial mix on good greens consists of Turface MVP (or similiar), perlite, peat, and aged conifer bark chips. Over the years I've almost eliminated the peat. I also add granite grit, which I am usually able to find in the form of chicken or turkey grit at the local feed store. Lo and behold, these are also the components of 'Al's mix'.

rhizo,

I hope I didn't overstep the boundaries here. Why do I feel like I'm being talked down down to or ignored? Please forgive me for intruding.

Clueless

My goodness, your experiences and comments are much appreciated. Certainly by me, and I'm sure by the rest of us.

I use plants for bonsai or otherwise that are nursery grown, often in containers (not always). Thus I have never had to deal with the tap root on those plants that may develop them. So, I guess I've avoided that issue altogether.

Years ago, I helped root prune what I recall was a pretty large Redbud that had been growing in a big container at the al fresco area of a restaurant. It had been declining for a few years, I guess. We did the 'surgery' in late winter, much to the shock and horror of passersby. Boy, was I ever relieved to see it rebound during the growing season! Whew. But again, that container was very large.

Your jade bonsai is terrific. Are the flowers fragrant? I may have to give a couple of my jade plants a looking over with bonsai in mind.

Dorie

Dorie,

The flowers are almost aromatic. Sometimes I imagine there is a fragrance. :-)

Guess I opened this thread when I should have been counting to ten thousand. It's been a trying day. Good luck with you plants. Hope I didn't ruffle your feathers too much.

randy

Oh my, I guess I didn't know that this would get so involved. If container gardening involves a lot of top and bottom pruning, I'm not sure if I should do it. Maybe I shouldn't even considered it at all. It's just that I have problems with my hands and arms (carpal and cubital tunnel syndromes) and maybe I shouldn't put the added stress on them. I'll have to think about this. If I do decide to keep them in containers, I now know that I'd have to somehow obtain much bigger containers that I have now, and I'd also have to learn about container gardening. I guess it's more complicated than what I thought. I enjoyed your picture, Randy, and I appreciated your comments and those of everyone else. This certainly has given me much to think about! Thanks everyone!
Cathy

I have a whole lot of stuff, including trees, in containers right now (Home Depot has loved me this spring) but it is just supposed to be temporary until I figure out where things are going. I'm hoping to plant the trees in the fall after they go dormant. We shall see.

Just checked and I have my trees in 8 gallon pots.

The only related taproot experience I have is with pawpaw. I moved a couple last fall. I believe I planted them in 2007 and they were about 10" tall when I dug them up. I'd swear the taproots were 3' long. I couldn't believe it. I eventually quit trying to save all of it and just yanked. They are not showing signs of life yet but the wild ones around here are still dormant too.

KC

Cathy, if you do decide to go through with this I would suggest you try Dwarf Hackberry (Celtis tenuifolia) if you wanted to grow a hackberry in a pot. It's naturally small, slower growing, and tolerant of trying rocky conditions in the wild so it might take pot culture much better than some others. I know forestfarm has carried it in the past.

The only trees I have kept in pots are willows and usually shrub-type willows with the exception of one babylonica which is in a five gallon pot for several years now and is doing okay at the moment. The others are all in 15 gallon pots that I get from Home Depot. In fact, I just planted a giant pussy willow in one of those pots yesterday. I use the pots because my yard is tiny and I have to control myself because I am a plantaholic and it is very hard to keep myself from doing outrageous things in the yard. And I use willows because I get tiger swallowtails who lay eggs on them. I also get sphinx moths and underwing moths who use them also. Just be very careful putting the pots on the ground or you will likely end up with a tree in your yard and not in the pot. And it doesn't take long either. When the trees do that I end up having to brake off the roots that are in the ground and cut back top growth and see what happens. So far, I have not lost any though some are "stationary" shall we say. Murray

Murray,

I was hoping that E. Tigers Swallowtails will use willows in the northeast: NJ. I hope that Red-Spotted will use blueberries and juneberries. I may plant a Pin Cherry, instead of a Black Cherry, although I don't know if it will grow too large itself. I wonder if Dwarf Hackberries taste especially good - i.e. edible landscaping?