1 foot or 15 inches is about the minimum clearance I wouldnt put any type of vines even close to a condenser for it will start getting into the unit and wreaking havoc.

Thanks for the reply. Would covering the top with a finer mesh than the grate that is on there help with plant material? I guess I would have to clean blooms off in spring and leaves in fall. Suggestions anyone? Thanks!

Over the years I have seen people build "dog houses" for their outside a/c units made from trellis material. I have also seen solid plywood boxes with an open back used to encase an exterior a/c unit. All in the name of beauty and home design. These are not good ideas. Leave these to the design freaks at HGTV.

A/C units need to breathe. They need air circulation. The air comes in through the fins and is exhausted out the top of the unit. Anything that interrupts this airflow could possibly overheat the unit and even cause damage to it. These outside condensers were made to dissipate heat, not store it. The better the airflow the more efficient your a/c will operate.
We never put anything within 3 feet of our outside unit.

I experimented with mesh on top of my new unit to keep stuff out. I could not get it to look right. I think there might be a reason the manufacturers don't do this, probably airflow restriction. I try to clean the unit once a year by removing the fan a using the shop-vac to vacuum the debries that accumulates inside. CAREFUL with the cooling fins if you do this.