Ken, I've been trying to research online but seeing different info, plus, if something is suckering to me it could get indefinitely wide...

going to purchase plants tomorrow for a 50' long diervilla (bush honeysuckle) informal hedge, trying to figure out how many I need to buy.

thinking to buy 10 spaced 5' apart and hope they fill in eventually?

any ideas?

Diervilla is a modestly interesting shrub for difficult places, but is there some reason you want a shrub border of them?

What laceyvail said, and also, IME they don't get large enough to qualify as what I consider a hedge or a shrub border that will provide privacy.

Lacey & babs:

i bought them for this situation in my backyard, upon a bunch of your recommendations:

http://forums2.gardenweb.com/discussions/3522035/shrub-for-under-leland-cypress

I only need about 3' of height to cover the fence from view, then the conifers above will provide full privacy.

i ended up picking up 10 shrubs, couldn't decide on which looked better so I got 5 diervilla sessifolia "butterfly" and 5 diervilla rivularis "troja black".

got all of em 3g size, hopefully they will eventually sucker in to fill up. Will space them 5' oc 36" back from the edge of the retaining wall.

the nursery claimed they both get to 6x6 but... I see different stories about size online...

if by suckering you mean like crepe myrtle suckers or lilac suckers, then you should be removing them so they don't kill the main plant

I'm sorry I guess I used the wrong/confusing terminology.

i meant rhizomatic suckering as in this diervilla situation, when the tag says 6' width (ie 10 year width) is that for just the original plant or does that include the overall width of 10 years' rhizomatic spread/suckering?

another example might be like a sumac bush you know how they turn into large masses like this.

Matt, you are using the term suckering correctly and so is Caldwell. However, you are talking about different things. You mean a shrub whose normal growth pattern involves new stems sprouting outward in a way that slowly enlarges the shrub( a caning shrub), and it will do just what you want in your setting I think.

Caldwell is referring to grafted plants that send out sprouts from below the graft, and those do need to be removed.

The tag is referring to the entire shrub, usually at 5 years, but I would also look to see what MOBOT says about them.