While Leylands do grow fast (15-20' inside of 5-6 years), they also grow very tall - up to 70'. Do you really want that tall a screen? The width I have seen quoted at 15-20', and at 8-15'. If the wider width, then the hollies may get swallowed up by the Leylands - and figuring the correct spacing to block the distant view could be difficult - to get the screening you want in a reasonable time-frame, and still have the screen look good.

Nellie Stevens Hollies can grow pretty fast, especially if well watered - up to 20' x 10'. Another fast growing holly is I. x attenuata 'Savannah', a relative of 'Foster', also noted for fast growth, and good berry production.

The 'Emerald Beauty' arborvitae grows to 10-15' x 3-4', 'Nigra' to 20-30' x 4-5' and 'Brandon' to 12-15' x 6-8'. Clumping bamboos are another possibility. Camellias, if the right cultivar and a larger size is bought - AND if it's in at least afternoon shade - could be another possibility. And lastly, one of the evergreen viburnums might do. The last 2 would give flowers, and the hollies, berries.

As a rule conifer (and other) cultivars grow larger than dimensions given by commercial and other sources when site conditions permit. For example, the tallest Leyland cypresses in Britain are now over 120' high - eventually there may be one or more approaching double "up to 70'". Here in this part of USDA 8, the Seattle arboretum has a Leyland cypress over 90' tall. The same location produced an average crown spread measurement of 40' during 1993, perhaps using the same tree.