I have a planter that runs across the wall in my backyard. Currently it has a sprinkler system that is controlled by a single valve. There are about 6 sprinkler heads along the planter, each about 5-6 feet apart. I wanted to convert to a drip irrigation system and had following questions:

1 - Can I cap off 3 of the 6 sprinkler heads and install the drip irrigation on the other 3 and still have enough pressure for the drip irrigation?

2 - I am assuming I do not need a backflow preventer since the control valve should already have that. Please correct me if I am wrong.

I am planning on getting one of those conversion kits to install the drip irrigation.