Mine are always rootbound when I buy them. Haven't had much problems I could really attribute to the rootbounding, though. Sometimes they have really been in the pot too long, and the plants look somewhat stunted, maybe a few yellowing lower leaves, leaves kind of leathery instead of young and full of growth, etc., and these don't seem to ever amount to anything--figure they are too old, which is likely on a clearance sale, but also figure they probably didn't get good care and dried out pretty badly a few times. However, I have been told to take part of the rootball in each hand and pull sidways until it has split about halfway up. This breaks the roots and tends to stimulate new root growth. In the ones that you dug up, were there any new roots extending out from the rootball? Have they been getting enough water? Transplants dry out surprisingly fast before the roots get extended out into the soil, especially if the top of the rootball is visible on the surface. If not watered frequently, they could just be sitting there due to drouth stress. If there were new roots, I'd just make sure they have good fertility and moisture and see what happens. If no roots, try splitting the rootballs a bit and replant. If you don't have room to keep them to play with and plant new ones, then toss and start over.

This is a copy/paste job from something I left on another thread a while ago: In my estimation, the only convincing case to be made for reusing container soils is one of economics, and you'll never find me argue against making that decision. If you can't afford, you can't afford it. That said and setting economics aside, you might decide to reuse soil for reasons other than economical. Perhaps the effort involved with acquiring (or making your own) soil is something you might not wish to go through or be bothered with. In any case, it would be difficult to show that soils in a more advanced state of structural collapse can somehow be preferred to a soil that can be counted on to maintain its structure for the entire growth cycle. So, if the economic aspect is set aside, at some point you must decide that "my used soil is good enough" and that you're willing to accept whatever the results of that decision are. All soils are not created equal. The soils I grow in are usually pine bark based & collapse structurally at a much slower rate that peat based soils, yet I usually choose to turn them into the garden or give them over to a compost pile where they serve a better purpose than as a container soil after a year of service. Some plantings (like woody materials and some perennials) do pretty well the second year in the same bark-based soil, and with careful watering, I'm usually able to get them through a third year w/o root issues. Watering habits are an extremely important part of container gardening. Well structured soils that drain well are much more forgiving and certainly favor success on the part of the more inexperienced gardeners. As soils age, water retention increases and growing becomes increasingly difficult. If your (any one's) excellence in watering skills allows you to grow in an aging medium, or if your decision that "good enough" is good enough for you, then it's (your decision) is good enough for me, too. The phrases "it works for me" or "I've done it this way for years w/o problems" is often offered up as good reason to continue the status quo, but there's not much substance there. I'm being called away now, but I'll leave with something I offered in reply on a recent thread: "... First, plants really aren't particular about what soil is made of. As long as you're willing to stand over your plant & water every 10 minutes, you can grow most plants perfectly well in a bucket of marbles. Mix a little of the proper fertilizers in the water & you're good to go. The plant has all it needs - water, nutrients, air in the root zone, and something to hold it in place. So, if we can grow in marbles, how can a soil fail? Our growing skills fail us more often than our soils fail. We often lack the experience or knowledge to recognize the shortcomings of our soils and to adjust for them. The lower our experience/knowledge levels are, the more nearly perfect should be the soils we grow in, but this is a catch 22 situation because hidden in the inexperience is the inability to even recognize differences between good and bad soil(s). Container soils fail when their structure fails. When we select soils with components that break down quickly or that are so small they find their way into and clog macro-pores, we begin our growing attempts under a handicap. I see anecdotes about reusing soils, even recommendations to do it all over these forums. I don't argue with the practice, but I (very) rarely do it, even when growing flowery annuals, meant only for a single season. Soils don't break down at an even rate. If you assign a soil a life of two years and imagine that the soil goes from perfect to unusable in that time, it's likely it would be fine for the first year, lose about 25% of its suitability in the first half of the second year, and lose the other 75% in the last half of the second year. This is an approximation & is only meant to illustrate the exponential rate at which soils collapse. Soils that are suitable for only a growing season show a similar rate of decline, but at an accelerated rate. When a used soil is mixed with fresh soil after a growing season, the old soil particles are in or about to begin a period of accelerated decay. I choose to turn them into the garden or they find their way to a compost pile. Unless the reasons are economical, I find it difficult to imagine why anyone would add garden soils to container soils. It destroys aeration and usually causes soils to retain too much water for too long. Sand (unless approaching the size of BB's), has the same effect. I don't use compost in soils because of the negative effect on aeration/drainage. The small amount of micro-nutrients provided by compost can be more efficiently added, organically or inorganically, via other vehicles. To boil this all down, a container medium fails when the inverse relationship between aeration/drainage goes awry. When aeration is reduced, soggy soil is the result, and trouble is in the making. Al

There is no way I can possibly replace all the potting soil every year in all my containers. I too used to use garden soil for containers for many years and it mostly worked until one year we had a drought and then everything went haywire with the garden and I stumbled upon that container soil thread here. Al's pine bark recipe drains a bit too quickly for me and I would never be able to keep up with watering during the summer plus I have so much soil that it would be impractical to get rid of it. So last year I improvised and used this formula: 2 parts old soil 2 parts pine bark 1/2 part peat moss 1/2 part perlite and then 3/4 cup/cu. ft. slow release fertilizer. This means that for every container changed generates 60% in excess dirt. Factor in the old plant and roots and it's about 40%. If I increase the size of the garden by 40% I usually don't have any excess. I don't have anywhere to put excess dirt since I have no yard. After the first year the old "soil" has lots of perlite, decomposed pine bark, and looks a lot better. Mixing that with the above formula leads to a potting mix even more aerated and as the years go by, my soil should just get better and better. Last year I had my best tomato crop ever (but still plenty of areas for improvement). Tomatoes are my benchmark crop since they were the crop that suffered the worst when I used plain old garden soil. Since this year I can't expand the garden that much I ended up with a lot of excess dirt that I've been trying to give away to the neighbors. One neighbor noticed that my old soil looked better than the potting soil she bought from the store since my old soil still had a lot of perlite in it from last year. This Spring I replaced all the soil for the first time in 4 years in a 8x2x1 deep container, by the front sidewalk where many people walk by, with that pine bark mixture. Many people who walked by asked me why I used mulch as potting mix since it seemed so odd. Even the nursery where I bought the pine bark looked at me cross eyed when I told them I used this stuff for potting mix. I guess hardly anyone does this around here which seems odd since it does work well and it's much cheaper mixing your own than buying the premixed bags at the big box store. Just my $.02 on reusing soil.

Next time you go to buy a tree, pull it out of the pot before you buy it. At least in a normal pot, you should see fine roots around the outer surface of the rootball. You may even see a few that are a little larger, but they should not be so big that you cannot either straighten them out (when you are planting the tree) or prune them away (without worrying about hurting the plant). At planting, you really don't want any roots circling around the rootball or kinked in knots. Your tree's roots will grow larger and larger as the tree grows, so picture the rootball as all those roots grow many times their current size. If all the roots are locked into a tight ball (or pot-shaped cylinder), the trees root system will not be sufficient to support the tree or supply water and nutrients. Even if some roots are able to grow out away from the tree, a potbound rootball will become more congested with age, and failure will become more and more likely. Some people even recommend complete removal of all potting material during the planting process. They believe that poor root system structure is so important, that the extra shock, brought on by bare rooting, is worth it. Personally, I prefer a more modest approach. I remove a lot of the excess potting material, but leave all that I can while still being able to ensure that all the roots are straightened out and growing away from the tree. Usually, I form a cone at the base of the plant that allows the roots to radiate away from the base of the tree and slightly down into the soil. If you have questions about this, please let me know. Sometimes describing things like this in few words is not easy. Also, see the link below for what I hope are very helpful instructions about how to plant a tree or shrub. Here is a link that might be useful: Planting a Tree or Shrub