Watering

is it ok to water at night?

If by night you mean when you indoor lights are off, you can. However, I have always been told that it is better to water just prior to "daytime". That way if the leaves are wet, they have ample opportunity to dry off and reduce the chance for mildew. For the record, I'm not an expert ... just passing on the info I have read or been told. Cheers.

It rains at night where I live.

i would agree with incog , i tend to do my watering just before lights on .

I'm doing outdoor guerilla and only time I can get to my garden is sundown

If your outside than no issues just don't get much on the leaves.