Thanks tsugajunkie! That's good to know!

I don't know how closely Centerglow compares to Coppertina in size, but my Coppertina reaches 4'-5' from the center in all directions and has overwhelmed several smaller plants that I was unwise enough to plant too close to the ninebark. My Coppertina was just starting to arch the beginning of its fourth growing season, and by the end of the season it had grown down to the ground and was trying to root at the branch tips.

Thank you for this info, nhbabs! I'll make sure to plant perennials far enough. According to Monrovia's web site, Coppertina is taller, but Center Glow is slightly wider.

I'd probably take the larger sizes of what Monrovia suggests for safety, and perhaps add a bit on top of that. IMO this is a shrub that looks better without pruning. You could plant annuals or low-care bulbs such as daffodils (my daffs are done blooming before the ninebark leafs out) within the ultimate range of the shrub or place pots of plants to use the space until it fills in.

Beginning with 'Diablo'...I've found most of these colorful-foliaged ninebarks to be too tall-growing for any but the largest shrub borders. Of course, the other cultivars mentioned here all represent efforts to shorten the plant up. Cool plants, just hard to fit in where space is tight.

As far as the "how soon" question, we can perhaps offer very general guidelines, but in the main, that is going to vary with your local growing conditions....same as for any other plant.