Shawn, how much below 50F? D. marginata will thrive at 50, but the soil should be kept semi-dry, otherwise roots can rot. Even indoors in warmer conditions soil should dry between waterings, but cold will cause problems.
If temps are not much colder than 50F, perhaps you can prop up the pot? Toni

Shawn - D. marginata is only listed as hardy to 45* in the ground, which would be to zone 11, maybe 10 with good protection. That, in consideration of the fact that soil temperatures would be much higher than 45* because of the moderating influence of the earth. In a pot, soil temperatures soon equalize with ambient temperatures, so soil temperatures in a pot at 50* ambient temperatures would be much lower than the soil temperatures of the earth in zone 11 at 45*. IOW, your plant won't thrive, or even do ok at 50* temperatures. At best, it will only tolerate 50* temperatures temporarily. Even temperate plants don't thrive at temperatures that low.

Houseplants need warmth. 65-80* are best, and once night temperatures start dropping below 55* on a regular basis, the plant should be brought in, regardless of daytime temperatures. Another strategy would be to bring the plant in to protect it from chill (below 55*), and then move it back outdoors as temps allow (above 55*).

Many tropical and subtropical plants are unable to carry on photosynthesis at such low temperatures. If the plant is not producing food, it means it is depending on stored reserves to fuel its metabolism - it's running on battery power with no way to recharge the batteries at temps below about 55*. Additionally, when you DO return the plant to more favorable temperatures after exposure to chill, the return to normal photosynthesizing ability doesn't return quickly. The return to normal ability might be measured in days instead of hours. When a plant is using more energy than it is making, it will die unless the condition is corrected.

Rule of thumb for most houseplants: growth and photosynthesizing ability begins to be impaired at about 65*. Below 55*, growth and photosynthesis nearly stops and the plant goes into decline. Fertilizers containing ammonia and/or urea should even be withheld at temperatures below 55* because nitrifying bacteria become inactive and ammonium toxicity becomes a real threat.

Al