(04-11-16) We just experienced a hard frost here in the northeast; evening temp dipped below 20 degrees. Some of my perennials were up and blooming - daffodils, spirea, bleeding hearts. Since it is currently the spring season, how do I proceed with the spirea and bleeding hearts? I did cover the hearts with landscape cloth (good choice?). Some articles say to fertilize, some say not. We are expecting warmer temps this week - 60-70s. Typical spring in central PA!
Frost Bitten Plants
Certified GKH Gardening Expert
The plants you mention should be fine in brief dips in temperatures and light frosts.
Covering is fine to ensure that you don't lose buds and flowers, but make sure you uncover as soon as it warms back up in the mornings.
Here are some articles with care information for your garden plants.