Making Hedge Thicker By Planting Double Rows

[W]

I am building a hedge to the street with Photinia Red Tip. The young plants are not really blocking much of the view. What are the pros and cons if I plant double rows of plants, spacing two feet between each row, and two feet between each plant on one row?

Since the plants would be back to back, the street facing row would get sun in the morning on the street side, but would be denied sun on the back side at all times of day. The lawn facing row would get no sun in the morning, but lots of sun in the evening. I guess that means the inward facing parts of both rows would die off over time. But would planting double rows make the hedge thicker and block more of the view from the street?

[Brooklyn1]

If yours are a deciduous variety they won't offer much privacy regardless how many rows you plant... if an evergreen variety one row would be sufficient as they are a dense plant and usually grow quite large and if in rows they will shade each other so the inside parts will be bare anyway.

[David E. Ross]

In the end, the die-back where the two rows face each other will defeat your intent. This can be sufficiently unhealthy for the plants that you put their survival at risk.

As an alternative, consider planting the Photinia in a single zig-zag line. This could be created by having two rows with 3 feet separating each row and 3 feet between plants. A plant in one row would align with the gap between two plants in the other row. From your description, each row would then get sun on both sides.

In many situations, good gardening requires patience. Instant results are not possible even with Photinia, which grows quite fast.