Plant them. maybe toss in 1/4 compost or less to loosen the clay (only use compost). I've seen plenty of screens with 8 foot on center Picea abies screens.

Dax

Follow Dax's advice. We have Norway Spruce planted in pretty heavy clay soil with no amendments added and they're doing just fine.

8' spacing is good for a start, but as the trees mature they will need more room. For a single line of NS trees the eventual spacing should probably average 16 feet or more. But that could be many years away. 6 years ago I planted about a 200 foot line of NS on my property line and planted them a little more than 8' apart--for mowing and fencing purposes (I now have a new properly line and will be planting a line at least 800 feet long--I will post about my plans for that soon). About half of these trees I planted 6 years ago are really strong, the other half will be smaller and will in a few years be overwhelmed by the stronger ones. I will probably thin out the weaker ones in just a few years to give more room to the stronger ones and make the line look better.

One "problem," sort of, is that the good ones and the weaker ones are not always every other one. I may have two strong ones, then a weak one, then another strong one, then maybe three weak ones, two more strong ones--you get the idea? So in the end I may have two spaced 8' apart, then 16 feet, then another tree, then maybe three weak ones together, and here I could cut all three and have a space of 24 feet--not too bad when the trees get really big, or I could save the middle weaker one for a while. So the spacing is irregular. For me this is OK, but some people might want the eventual line of mature trees to have equal spacing. I don't know how to do that if you want to start with closer spacing and then eventually thin them for wider spacing, saving the best trees.

Well, I am sure you get the picture. Now I admit I am a Norway spruce nut, which I am sure you know by now if you have been reading my posts here for a while. NS trees have a lot of variability, and the really best ones are really, really beautiful. So I am always advising planting them so there is a maximum opportunity to get the maximum number of really beautiful ones--with fast growth and the dense weeping foliage, etc. So the more trees one can plant and the more opportunities one has to thin out the weaker, less beautiful ones, the more georgeous the final result. A triple row (offset) with the trees 6 X 6 is probably the best starting place I can devise. But planting this close requires a lot of trees and a lot of thinning, and a lot of difficulties protecting the trees and mowing around them etc. I doubt I will do this even for the screen that I am planning for my own property. I may do two staggered rows with each tree 10 feet apart with the rows 6 or 8 feet apart for the initial spacing. I am still thinking about what I will do.

Anyway, enjoy your trees. If you want them to get a really, really good start, I advise mulch and regular watering the first year, and watering during dry spells for two or three years after that.

--Spruce

This is late, but it may help someone else.

For a long screen I recommend alternating conifer and quick deciduous. E.g. Norway spruce, trembling aspen. A shrub for the in between also works. Dogwood, lilac, caragana, buckthorn, chokecherry.

Here's my thinking:

1. The deciduous tree grows like a weed and gives you quick screening.

2. Spruce on 8 foot centers will conflict for resources by the time they are 20-30 feet tall.

3. If you plant a throw-a-way tree like poplar, by the time the spruce are big enough to fight, the poplar will be ready to be laid up for firewood.

Second caveat:

Plant two rows. But the second row has the spruce aligned with the poplar. In the long run this gives you a zig zag row of spruce.

Third caveat: Make sure your lawn mower can do a slalom course down the row. This makes it a lot easier to control grass and weeds while getting them established. I found that at 8 foot spacing I couldn't slalom, but at 10 feet I could.

PFRA now recommends 10-12 foot spacing for shelterbelts where before they recommended 8 for most conifers. I'm now telling my customers 8 feet for spruce and 12 feet for all but the narrowest pines.

Thanks, Sherwood for this valuable information about how far to space Norway Spruce. We just bought several trees to hide a bike trail that basically parallels our driveway -- we want to hide it and the powerlines across the street. We also bought a Sequoiadendron for this space; thinking that they will all three make a dramatic screen.

How long is this line of spruces going to be? That would have a bearing on how many, how far apart, and the total cost.

Do you have the room or need to plant two staggered rows?

Sherwood, how do you propose to kill the aspens and cottonwoods after you cut them down? The roots sprout all over the place once they get large enough to cut down and both make poor firewood.

Mike

replying to a 9 year old post.. and debating a 6 year old reply is simply ludicrous ...

antonia has not really given us any information other than they bought some tree.. have a driveway.. and there is a bike path ... at least the power lines are across the street ...

it would be nice to know where they live.. what zone ... how long or wide the application..e tc ... before opining as to much of anything ... and a pic would be great ...

try all that.. in a new post ... they are free you know... lol ..

ken

place: South Lake Tahoe

Zone: 3

Planting area: to the right of that Jeffrey. 20 long, about 6 wide. The County chopped down the other two 50' trees to make way for bike trail which is just beyond the dirt patch...Cyclists have a clear view right into our living room window. Which is why we want evergreen trees there...

Trees: 1 Sequoiadendron, 2 Norway Spruce and mixed

understory to be planted later. (I.e. Dogwoods, wild rose, other natives.

Sorry, didn't realize that was a 9 year post. But thanks for info about 8 foot centers. Nothing grows very fast up here, so not worried about crowding.

Oh, BTW, we have already spent 7K replacing trees and restoring ambience the County has destroyed.