the distance between fence posts is 10'. The staked out area is an original planting area, 11' out from the fence. We prefer to keep to 7'

Be careful! Don't add an extra layer of soil around the oak. It can suffocate the roots and rot the trunk.

You can plant as close to the oak as you want, no problem there,

Re viburnum 'Winterthur', a lovely shrub, but a small one, only 4-5 feet tall, and without a pollinizer, you'll never get the berries. Plant 3 V. pragense, or use V. rhytidophyllum 'Cree', also evergreen.

Irrigation will not harm a tree that size. What if it rained most of the summer. Do you think it would die.?

Dig holes for each plant, and heavily mulch between them with wood chips. Just keep it weeded--not too hard a job. You can use round up first in the area if you want. If not, lay cardboard under the mulch. It works, I've done it for years and years.

Actually, I have--after reading up on the river rock maintenance, etc, decided NOT to go with river rocks after all.

I am just concerned that a swath of grass (whats currently there) in a 6' semicircle followed by a 5' swath of planting area (3 individual plants with mulch at each base? One big planting area?) may be a bear to mow/maintain.

The native oaks from arid regions (eg. California) don't appreciate irrigation if they haven't grown up with it. Your photos look anything other than arid...where do you live? Eastern North American oaks are much less bothered by irrigated lawns and garden.

Your gumball tree is probably a Sweetgum with shallow roots.

where is the prior post i replied to????

you are severely complicating your goal of sight blocking.. by limiting yourself to planting ONLY on the property line ...

one or 2 well sited trees .. closer to the house.. might solve your problem in a few years .. and then.. in the meantime.. those planted near the fence.. would have time to grow ...

ken

found it ... conifers are trees ... so you are most likely.. talking to the same peeps over both forums ... ken

http://forums.gardenweb.com/discussions/4846791/thuja-green-giant-what-is-reasonable-hedge-height-with-trimming?n=15

It is a terrible picture, but not totally worthless, and it sounds like it is time for some visual aids.

I have 3 oak trees in my backyard. There is another one directly behind the on in the picture, and a third one just off the right side. Underneath them is the species rose in the picture, the Viburnum plicatum 'Shasta' on the right side, mock orange on the left side, another Viburnum plicatum 'Summer Snowflake' beyond the mock orange, a forsythia past it, then coming back on the other side of the back oak a dwarf flowering quince, a Viburnum carlesii, and a bunch of daylilies. The other oak has a bunch of tree peonies, some hydrangeas, some ferns, hellebores and pachysandra.

The point of this is that you are plant just about anything you want under an oak. The shrubs are planted at least six ft from the trunks, but that has more to do with the shrubs than the trees. The space between the shrubs and the trees is either mulched or planted with groundcover.

Forget you ever heard about rototillers. Unless you are tending a large, conventional vegetable garden, I have yet to find a use for one. Shrubs are planted in holes, and not carefully spaced out. Murphy's Law is alive and well in gardening, and if you plan the planting holes out, you will hit major roots in almost all of those holes. It is much easier on the brain if you allow the holes to move a foot or two to get them between roots.

So long as you don't hit a big root, you can plant at the base of the tree. The confusing part is that some oaks, that live in completely different place, are finicky. Ours aren't. There are advantages to dealing with smaller plants that require smaller holes. That is how nature does it.