Purple fountain grass will grow the fastest and provide you almost immediate impact. However, it won't survive the winter (at least not in the Southeast). Morning Light would be the next best choice, in my opinion. It won't grow as fast as the fountain grass, but has a nice upright then weeping form. Karl Foerster grass is also very nice, but in my experience takes longer to become established and attain a nice size, form and flowering. My KFs didn't do much until the second year after planting.

Thanks for the input dawgie. I had been concerned that the size of my pots would be a limiting factor for these grasses. So then I'm thinking maybe thats a plus for purple fountain grass, since it won't survive through winter anyway, won't have to worry about outgrowing the pot. Immediate impact sounds good too.

ooops. Maybe upon further review purple fountain grass might be too purple for me. What about Miscanthus 'Purpurascens'in a container?

Purple fountain grass is VERY purple. I like it, though, and it flowers nicely as well.

M. Purpurescens won't have the nice form that Morning Light has, but probably will have more fall color. Morning Light is hard to beat for an ornamental grass -- beautiful form, variegated leaves, nice flowers. Another nice Miscanthus variety is Adagio, but its form is more of a round mound while Morning Light is more vase shaped. Adagio is very fast growing, but its ultimate size is small for a Miscanthus.

Grasses in containers are difficult to overwinter and do not have high rates of survival. Since perennial grasses reach their mature sizes no faster in pots than in the ground, it begs the question, "why?" And then, there is their late winter, early spring appearance and maintenence to consider. Dawgie's suggestion of Pennisetum rubrum ("Purple Fountain") is ideal on all these points.

That said, there are some grasses that do better in containers that do others; these are the cool-season growers, with a few exceptions. Miscanthus is not one of those exceptions, however. (Misc. purpurescens, by the way, is not purple at all. It is green all summer after it begins growth; only in fall does its foliage turn purple to red.

Cool-season grasses work better in pots because they start growth earlier, and some stay evergreen through winter. Excellent pot drainage, though, is an absolute must. Helictitrochon sempervirens ("Blue Oat Grass") is one such grass; so is Calamgrostis 'Karl Foerster,' Deschampsia, Fescue or Arrhenatherum ("Bulbous Oat Grass"Âwhich would look great in combination with P. rubrum.)

Warm season grasses that have worked for some (but not me) include Panicum, Molinia (must be kept moist), and some Carex like C. nigra. None of these will outgrow a 16" pot too quickly, but any of the Miscanthus, all warm-season growers, will do so before they reach their mature, 5'-7' heights. (So will 'Karl Foerster.') Also, keep in mind that hardiness ratings are significantly lessened by container-planting (see link below).

Here is a link that might be useful: Grasses in Containers

Great input. One of the things I am trying to avoid is picking a grass because of its great flowers and then finding out that it won't flower in a 16" pot.

Something I am unsure of is matching height of grass to my container size. What is the significance of outgrowing the container before reaching mature height? No flowers, looks stupid? Taking it to the extreme, if I wanted 5-7' heights in my 16" pots should I then plant a 14' foot grass? Put another way, if morning light would only reach 3' in my pots, should I just look for something that only gets to 3' anyway?

I also realize that M. Purpurescens is not purple. I like green better. I was thinking the fall coloring would look nice, even if it didn't flower.

Personally, when I put something in pots I want it to look good for an extended period of time. Are you wanting the pots to look good year round? If so, warm season grasses aren't going to do it.

I have M. purpurescens and 'Morning Light' and think 'Morning Light' would be more showy in a container. However they are both dormant for a long period of time.

Blue Oat Grass would be better since it is evergreen, well everblue. :) but it isn't terribly tall. Would look good in proportion to the pots though.

I buy purple fountain grass every year because it isn't hardy here and is such a wonderful color.

Ok, so I went to the nursery to buy some grasses. They had no purpascens, and the only morning light was in a big and expensive container, and it did not look good at all. You want to plant that? was the semi incredulous response I got. I now see the point about warm season grasses.

Plan B. I was tempted by the dwarf porcupine grass, but we already have some. I ended up settling on Japanese Blood Grass after all this. So much for my wall of grass.

I wouldn't give up yet. In my experience, most nurseries do not start stocking a good supply of ornamental grasses until the weather warms up in June. Most Miscanthus varieties are sort of slow to start growing, although my Morning Light is already about 2' tall, but it's been in the ground for about 3 years.

Really, I think purple fountain grass would be your best bet unless you just don't like the color. It grows incredibly fast, has nice size and form, and flowers nicely. We grow them in pots in our yard every summer. You can readily buy them for $5 or less at Home Depot and other big box stores.