You don't say how long you need the privacy barrier to be. Also, how large are the trees? And how important is it that you have immediate privacy?

Anyway, here are some general guidelines. If you want the trees to each have room for good development for 40 years or more, they should be planted at least 15 feet apart in each row--they could be planted 20 to 25 feet apart. If you plant staggered rows and want a fairly tight kind of screen/barrier, the rows could be as close as 10 feet, but for ideal development of the individual trees, maybe 15 feet or more is better.

I think you have some flexibility. If the individual trees are planted 20 feet or more apart in each row, the rows can be closer--as little as 10 feet. But if you want to have the trees closer in the individual rows, then the rows should be further apart.

Not seeing your site and not knowing exactly what your preferances are, a good balance of spacing would be individual trees in the rows 20 feet apart, then the rows 10 feet apart. This way if you are back aways from the rows the trees will look like they are 10 feet apart, and having the rows 10 feet apart will make a fairly tight screen even if one is closer and looks at it from an angle. And the individual trees will have room for good development.

But if you don't need a lot of privacy soon, you could add a few feet to the spacing. The ideal spacing also depends on the kind of soil you have which affects how fast the trees will grow and how large they will eventually get.

--Spruce

Spruceman knows his spruces! Also be aware that Picea abies is extremely variable in size and shape (just look at the number of cultivars out there). Plant as Spruceman suggests, but keep an eye on them and perhaps tweak their positioning in 5-8 years.

tj

tj:

Yes, the variability from individual tree to individual tree is something to consider. If the trees to be planted are larger--4 to 6 feet or more--then it is more difficult to accomodate that. People don't like to plant a lot of extra trees when they cost what trees that size usually cost and require some effort to plant them.
If one has small seedlings to plant, and plenty of them, and really wants to see the best that NS can do, then I recommend planting trees 6 feet apart in the rows. This way the more vigorous trees will dominate and the weaker ones can be thinned out. One can also thin to favor the trees that show more graceful weeping foliage or other favored characteristics as they grow larger. The eventual spacing after the trees are 60 years old should AVERAGE about 25 feet on good sites.

One problem with this is that when screens are planted this tight, they are usually never thinned out, so the weaker trees remain, get overgrown by the stronger trees, and then look ugly. I was in Oakland, MD this last weekend and saw just such a screen right on a residential street. The dominant trees were about 70 feet tall, but between each there were one or two weak overtopped trees, anywhere from 20 to 35 feet tall, each with a lot of dead lower branches, that did not add to the beauty of the screen.

Another problem with this method of close planting and later thinning out the weaker trees is that the eventual spacing between the dominant trees will be very irregular. Sometimes two strong trees will grow next to each other, and then three weak ones can be in a line and will have to be thinned out, leaving wider spacing, etc. For my tastes this is not a problem, but some people like trees in a screen to have regular spacing.

But all this is not to say that planting with the spacing I recommended above will not result in a beautiful screen. If the weaker trees have a lot of room, they will grow well because they are not in direct competition with the stronger trees, and they will contribute their part to the screen. If the trees are already 4 to 6 feet tall, one can already see if they are good trees--there should not be any real runts included if they look strong when they are planted at that size.

--Spruce

Thanks Spruce! My trees are 7-8 ft. and the barrier needs to be about 200 ft.

Of course we'd like to have as much privacy as possible, as soon as possible, but I would like to ensure the proper growth and maturation of these trees in the long run. So I need a compromise.