I have a rose garden with thyme as a living mulch/ground cover. It gets whatever rain comes in winter and the water I use to hose down bugs and dust off the roses about once a month. A friend told me that I would be better off having a dry mulch (bark, pine needles,..) the roses would need less water(drip system) because the thyme is taking up more water than it prevents evaporation. Is this correct? And if so how much water would I be saving (is it worth it?) I would love to have an other opinion.