Seems like this exact same thing happened last year! There are predictions for anywhere from 3-10 inches of snow from later tonight into tomorrow morning for the Denver metro area. Along with the snow, temperatures will drop below freezing tonight and Sunday night.
Here are some tips to help your flowers survive the weekend:
If you can move it, bring it to a sheltered patio area or into the garage
Put old socks or golf club heads over your iris flowers
Drape a sheet over large bedding areas
If you have planted anything tender (basil, tomato, peppers, eggplant) cover them with pots or containers
Use old plant pots to cover anything that is in bloom with fragile flowers like a columbine or rue
Watch the branches of your shrubs and trees. If we do get a lot of snow shake or use a broom to knock the snow off to minimize damage.
Most perennials should do fine, but if they are newly planted cover them as well.
Even though this late snow can be tough on our vegetation, the moisture is so beneficial, it is worth the wet socks and yogurt containers all over the yard!