I agree with kentuck that mowing does not keep the rhizomes from spreading further. On the other hand, the rhizomes will not kill your bulbs. I grow the bamboo and my other half grows the flowers. Our plants are completely intermingled, with no harmful effects on either. The only downsides are: 1) sometimes we will have a bamboo culm shoot up right in the middle of a clump of day lilies, and 2) sometimes when bulbs are being planted there might be a rhizome just where we are digging a hole (much as if you would run into a shrub or tree root).

I have a 60 ft. long privacy screen of Phy. Aurea. On my yard side I keep it mowed and it works fine. Last spring it put up a couple of shoots 18 ft. into the yard. Even though I mowed the shoots the rhizomes are alive and healthy. I recommend putting in a barrier or root pruning to protect your flower area. If you let them get established in the flower area, you will have to pay the devil to get them out later.
Having said all that, I re-read your post. You say you planted some "cuttings". What type of bamboo do you have? Is it a running type? or clumper?

I think that it's p. bissetti, the woman I got it from has culms that are about 1 inch or more in diameter, and about 25 to 30 feet high. It's also hardy in zone 5, so I'm guessing bissetti.

Thank you Kudzu and Kentuck for the information! I already planted all the daffy bulbs I am going to plant, and the township will mow that strip of land each fall, so hopefully I won't have any problems. I can also go out in spring and knock any new shoots over if I have to.

I'm chiming in late but will share the upshot of a conversation I had with an employee of the USDA experimental Bamboo station in Savahhah, Ga., during my visit there several years ago (not sure what it's official name was and which I understand is now no longer operational). Anyway, the 50' x 50' bamboo plots there were separated by 50' width grass pathways and mowing was the main method of controlling the spread of each species outside of its plot. The attendant told me that some of the bamboos did, in fact, spread beyond the 50' grass pathways and pop up in neighboring plots. Rhizomes would grow a number of feet each year and continue to live even though mowed and having no top growth. When they exceeded the grass path, they were home free in a neighboring plot. It can get vicious.

Last year, I came across a bamboo seller (in Alabama, I believe) who had a great website with LOTS of "how to" control information. You might try to hunt them down. Sorry, I don't remember their name.

I have observed groves where the owner does mow around their grove, but never thins out the bamboo. When there are too many culms to the point where the grove can no longer send out shoots through the middle, it will try to send out shoots progressively farther away. I've seen bissetii shoots from a 10ft tall grove with shoots popping out around 15ft away and no shoots emerging anywhere close to the grove. On the other spectrum I've seem an aureosulcata grove where the owner seems to have the grove thinned annually and fertilized. I'm not sure if he rhizome prunes however shoots are not emerging any more than 1-2ft away form the grove edge and many are still coming out of the middle getting taller each year.

It looks like a combination cutting out smaller culms and rhizome pruning will restrict the spread of a bamboo.

As I mentioned above, they will run farther from the grove if given a chance for culms to develop leaves.

I know a man who used a shredder only once a year to shred around a grove next to his hayfield, but the shoots kept popping up farther and farther away.

Two things...he used a shredder, which left culm stumps that remained there and many grew limbs and leaves from these stumps, giving the bamboo a reason to keep spreading.

Secondly, he did this once a year. The new shoots emerged and had a month or so to develop before being cut down.

The man I mentioned in an earlier post above, cut around his grove at least once a week and cut as low as he could which gave the newly emerging culms no chance to produce food and spread.

Also I agree that if a grove gets too 'thick' with culms, it will produce and store food in it's rhizomes quickly and will spread farther than a 'thinned' grove.

The first year that I planted my black bamboo from a 1-gallon pot, it sat dormant till late Summer which it then put up a shoot 15 feet from the original plant. Bamboos will act differently in different soils and different climates, so what I see happen here may or may not happen in other parts of the country, so that needs to be considered.

I can only speak from what I have experienced here.

Kt