Hi, I know that subject line sounds like the lead-in to a joke, but...

In all seriousness I need to know what two separate plants will do when their rhizomes reach out and touch each other. :)

I am in need of a plant that will create a very dense hedge (not a total screen necessarily, just something that cannot be walked/wiggled through).

I've been to our local bamboo farm and I prefer the look of the common bamboo (vulgaris). I'd like to plant them close together in a line about 30 feet long, and watch them expand diameters over the years. How close is okay without weakening the plants?

The bamboo farmer says they'll fight once their rhizomes meet. I guess that means we'll always have a plant, then some space, then the next plant down the line, etc. True or not? This will be a major factor in our choice.

BTW Their 7-year-old plantings on display at the farm are about 10 feet in diameter, beautiful but I don't know that I can wait a decade or more to fill in the line we want with plants spaced 10 feet apart. The planned line of bamboo is in lieu of a fence on one side of our property.

Also, we have no worries about neighbors or space issues. We'd welcome the bamboo to spread out as wide as it likes (we're on 1.5 acres bordered by street on all sides). The crucial thing is that we want the rhizomes to grow side by side, with no plant-gap-plant-gap-plant at all, over time.