50F is quite low for semi-tropicals, but mirrors dry winter period , though outside temps go up to 60-65f during the sunny days and the humidity is higher then indoors. A lot of plants drop their leaves.
So in your case if you position yr plants near sunnier warmer windows when you go away, they will probably warm up to 60F, unless you live in colder cloudier climate, where temps near windows will drop at night 5-10f and won't warm up during the daytime.
for true tropicals temps below 60-65F for extended periods will mean death or severe decline. Basically it weakens the plants, so if they are small and not robust they will not survive. Weaker plants invite diseases and pests too.
