Interesting, I wonder why T5HO will have trouble with timers? I use a digital timer from HD and it works fine. I have heard that some T5HO have trouble with GFCI outlets but the better built ones apparently do not have that problem.

I use mechanical, the kind with the black circle you press down the plastic buttons for the run time. Pretty sure it is from Ikea. I do plug it into a surge protector. Never had a problem. My advice is to test for a few days before you leave.

While I don't have T5HO, I use a digital timer during the winter months with my T8's. I wouldn't want to have be home at the exact times daily to turn them on and off.

I had the mechanical timer before the digital. It started making a loud humming noise after about a month. Switched the the current digital last winter and haven't had any issues.

I've used a mechanical timer for 4 T5HO lights with a surge proctector for just 4 months and no issues- as yet.

I use digital timer from Amazon, one runs 3 36" t5ho's and the other runs 4 24" twin bulb t5ho's. About 8 months now and no problems.