It all depends on whether I'm adding to one of my collections or looking for a specimen plant for a certain spot. If it's just to add to a collection I buy small, it will grow. If I'm looking for a specimen plant to finish off a vision I have in my mind I'll go for it, I'll buy the one I think completes the picture.

Annette

I always buy the smaller plant. It makes it easier to tranisiton to my 'sea of clay' LOL.

They really do seem to adjust better, if they're smaller, when I plant them in the garden...and I can buy three or four smaller plants instead of one big plant!

I buy the one with the most "plant" in the pot, and usually the one in bud and not in bloom. Sometimes I buy the smaller one - I usually try and see what kind of root the plant has on it before worrying about the height and flower. After all, it's what's below that counts most ;)

If we're talking perennials, I tend to buy smaller unless it's something I know divides well and is something I want to have multiples of. I have found that big pots, with big plants that have completely filled the pot, are often rootbound and don't transplant well unless they are divided, and sometimes not even then. For shrubs and trees, I look for a vigorous plant that looks like it still has a bit of room to grow - i.e. is not potbound. For container trees that usually means something under 6'.

In general, my experience is that smaller plants are easier to get established.

Hmmm,, i prefer to buy bigger roses for quicker impact as im very impatient and dont want to baby little ones forever. But also because i have a hard time giving them alot of room if they are small (as if theyll never grow up!) But for most perrenials i buy the smaller size. Unless its something i have a hard time getting growing(like tall phlox, i dont know why it never takes off for me).
Generally i read the plant tags but never end up giving plants enough elbow room .

It was nice thinking about being in a nursery again!

A fixed budget means that I go for the small plants whenever possible. But it has a second benefit. I get to watch the plant grow. And I love that part more than the mature garden. Funny huh?

-woodyoak, how come you don't buy rootbound plants? I have heard other people saying the same thing, but am not sure why?? Is it because the roots are more likely to be damaged/disturbed when getting it out of the pot? Don't think I have ever lost a plant because it was rootbound that I can recall...though fungal issues is another matter!

-lilyfinch, last year in winter I even started dreaming a few times about being in a nursery!!! LOL.
CMK

Perennials, I would buy THREE of the smaller ones hopefully for the same cost as the one big one! I like to plant multiples and prefer to get 3 small plants with their own root structure than divide up a bigger pot.

Shrubs, I always buy bigger just because of our slow growing season.

Rootbound, I'll tend to buy rootbound perennials and not worry too much about it. Trees and shrubs are another story, but I can say I have planted plenty of rootbound shrubs and trees and they seem to do fine as long as the roots are "dealt with" before planting.

For me it depends on so many things that can vary day to day. I bought roses in large pots as I know they need every advantage in a cold climate and I was impatient for blooms. They were in bloom when I got them at the end of June on sale and continued without a pause until well after freeze-up so it was worth it.

Plants that are new to me I sometimes buy in small pots - got my Walker's Low in a 5" pot and it took off unbelievably, should have got 6, and will get more next year.

If I want/need a lot of a certain type of plant such as the lavender I bought in a small flat of plugs as they were very inexpensive. They are also marginal here so I haven't lost much if only half survive.

For shrubs or trees I like to buy in larger pots. And I prefer they not be too root bound as it's just an extra stress for the plant. If I'm paying the big bucks for a potted tree I want it in very good condition.

I'm usually very frugal but it does depend on how desirable the plant is to me and how nurturing I'm feeling at the time. I've babied plants for decades so sometimes don't feel like taking on more. But every year do buy a few I know need it.

Overall I buy more small potted plants than large simply because they are a better buy and I can wait for them to grow.

CMK - rootbound plants are often weaker than those that haven't reached that state, so they often don't thrive after planting, even after cutting off some of the root mass to stimulate new roots. Rootbound perennials have a better chance of surviving than shrubs and trees do in my experience. But it has to be a really good deal on a plant I really want before I figure it's worth the cost. Often a smaller (and cheaper) plant with healthy roots will have caught up or surpassed the larger one within a year. So it's usually not worth the extra effort to deal with the rootbound plant.

I'm always opting for small sized ones. For various reasons including:

That I'm patient and willing to wait it grow out.
that it's easier for the plant to transplant and easier for the plant to recover.
that it's the right price.
that I know how fast or slow a plant develops.

For example, this summer I was searching for a Hakuru Nishiki for my cousin and myself. One nursery priced it high because it was a large plant and tree shaped. I later found it at another centre for less than half the price because it small and bush shaped. I opted for the small plant because I knew what I needed to do to shape the plant into a tree. Also because the plant should achieve full size by year 3.

-woodoak, ah! I see. Thanks for the explanation on that one! ;-)
CMK

Perennials,smaller. Reason, like many of you, so I can buy mmore, and within a short time,they catch up anyhow. Liked the comment about enjoying the garden grow..sort of like children!
Shrubs, woody plants I usually buy on the larger size.
We did plant3 blue spruce years ago when they were just 10"tall. They ara tall, beautiful trees now. Sometimes you have to consider how much wildlife problems you have, too, which we don't even in the country.