Hello,

One idea is to bury a big perforated pvc pipe next to the roses. It should
have a T-opening where you can fill in the water. You probably can get one
in the junk yard for free.

As the water leaks, it will feed your roses. Less water will be wasted
through evaporation and most importantly the rose leaves won't get wet and
cause black spot etc..

Cheers,

Yau-ming