Tall Hedge Infill
We have a 9' tall, 10' wide hedge on the south side of our front yard. Over the years (~20) I've cleared out old, dead portions, mostly in the middle. I'd like to try rebuilding the hedge by planting in the middle when the leaves are off, and there's plenty of sunlight. The hedge seems to be made up of several plants, but I'm wondering what type of plant you recommend or this project. I know another alternative is to dig it all out and start over, but we'd like to maintain what is there if we can. Our neighbor to the south removed his entire lawn and replaced it with rocks. We'd really like to protect our "barrier" if we can.
Given the age and location of your hedge, it most likely started out as a uniform row of Privet (Ligustrum). Over the years, other species probably seeded in - things like Common Buckthorn (Frangula) and Cotoneaster - dropped by birds or blown in by wind.
A good place for you to start might be getting at least the dominant plant identified. In Denver, bring a sample (a 12 -18" long branch showing the bud arrangement and fruit, if any) to the Extension Office at 888 E. Iliff (in Harvard Gulch) or, on Tuesdays 1-4, to the Master Gardeners at DBG (in the library). Call the Extension Office first to make sure someone is available at 720-913-5270.
If yours turns out to be predominantly Privet, then Cheyenne Privet (L. vulgare 'Cheyenne') is a good, readily-available choice for filling in your holes.
If you are not concerned with uniformity, there are many other species you could use, like Lilac or Siberian Pea. Here is a link to a CSU Extension fact sheet on Hedges that lists a number of possibilities. It also gives you some pointers on maintaining and rejuvenating a hedge: http://extension.colostate.edu/topic-areas/yard-garden/hedges-7-208/
Thank you so much for your reply. What a wonderful resource "Ask an Expert" is. We will definitely follow up to act on your suggestions. Thanks again!