I know the question sounds strange, but do I need to divide them at all? I am afraid if I don't divide they will die off or something.

no, they never have to be divided. Of course you can if you want to multiply them to other locations in your yard. The best time to do it is in the early summer when they are about 2-3 feet tall. They can grow together forever though and it doesn't hurt them at all.

Here the Musa's are along with an Ensete and my pooch.

They look bigger in real life, actually. I am glad to know I don't need to separate the clump. I may give a division/ thinning to a friend though. I have to store the Ensete for winter though. I wish I knew how to protect and leave in-ground in zone 6 . It is zone 8 hardy. The Musa's of course can stay in the ground.

My experience over 7 yrs, starting with one musa basju: I've gotten several new pups each summer, and the mother plant will die eventually, after it blooms and puts out a small hand of bananas. I recall reading that a musa puts out a certain number of leaves, blooms, and then dies (I don't recall how many leaves). I've lost one plant, the original mother, in 7 years of growing. I have a nice banana grove that is not too large, and it surprises my neighbors and passersby!

I've never had to divide M. basjoo; it does just fine being its rampant self.

I also have a black Lab but don't bother dividing it either. One is plenty. ;)

M. basjoo is basically a giant perennial but they have such large rhizomes and root systems I suspect they would be difficult to divide like any normal perennial. I've had a similar problem with my tiny urban garden getting overwhelmed and shaded out by a single M. basjoo clump but I've found you can control the growth (somewhat) by removing the outer pups when they're small--just get a firm grip with dry hands and give them a hard, sharp yank. They will pop off just below soil level.

I planted this M. basjoo in 2002 and it has never been divided--I've only controlled it by the method I describe above. And I didn't even fertilize it this year--I thought maybe it would stay small but so much for that!

That's funny eric, he's actually a Newfie/black lab mix. Jonnieb, I am going to try to give some pups (musa) to a friend next spring, I hope roots will come up when pulled, well, I can use a hand shovel to get some roots when I pull. Mine weren't fertilized, but the ground in that area was once a horse manure pile or close to one in the past, so that explains the size after 2 seasons. Rainydaywoman, I will try to take some babies from the middle too, I have an area downslope that I will try one because it stays moist after rain and I am sick of the weeds constantly popping up, the bananas can shade and take up some of that area and make it look nice too.

I forgot to ask, jonnieb, is that palm in the ground? I have one in a pot and another type in the ground. Yours (windmill?) is in a pot for me here. I may wrap in burlap and put in my cold greenhouse. My inground will be wrapped good and left inground, I may add lights.

Musa basjoo is pretty easy to propagate from pups--use a shovel to make sure you get some of the rhizome along with roots. Heck, I've had sections of rhizome that I threw on a compost pile start to sprout without any assistance.

Yes, all my palms are in the ground. I don't protect them except for mulch. The oldest one (Trachycarpus wagnerianus) has been in the ground about 10 years, planted as a very small seedling. The larger windmills (Trachycarpus fortunei) have been in the ground about 7 or 8 years, also planted as very small plants. They do well as long as winter temperatures stay above the single digits. I have a series of photos showing their growth over the last few years (see link).

Here is a link that might be useful: Palm Progress, 2009-2013

I started some palm seeds this past spring. I got them from ebay. Out of many types I tried I only succeeded with what I think is the Wagneranius ( Fortunei?) I had 2 when I checked a couple days ago. Not sure how to overwinter. Maybe protected in my cold greenhouse, where I put my potted waxier fronded Trachy windmill . You have the room for a live oak? I successfully overwintered 2 Live oak "late drop" from Mossy oak natives nursery. They are a possible hybrid of 2 different live oaks . They overwintered, though admittedly only one winter so far, that's better than the other live oaks I've tried. The last one was from coastal Virginia, as far north as they grow, it died after about half of the winter, as the teens and a few single digits came along. I have read that the plain old Live oak of the south is planted in DC. I THINK one is near a museum. I know there is at least one somewhere in DC. If you are in the concrete jungle area and have some yard, maybe the plain old Southern Live oak will fare well.

I want to add that if someone in zone 6 or 7 wants to try a hardier Live oak, look up Live oak "late drop" on the Mossy oak natives nurseries tree site. I had good luck in zone 6 Pa, with 2 of the Live oak "late drop" doing great in the winter of 2012-2013. They are listed as zone 7 hardy, but I had 2 of them do great the winter of 2012-2013. It is not a promised success, but a possible success.