The first flowers in our yard are always the snowdrops by the corner of the playhouse. Years ago I buried a big rock there and left a little bit of it above ground to catch the sun. This warms the soil around the rock and helps give these early spring flowers a boost.
Other people plant spring bulbs near the foundations of their homes because that soil warms up sooner than the rest of the yard. We don't have flowers in our yard. Our mature maple trees limit us to growing hosta, moss, vinca and rust.
While I was tiding up the garage today I read the bag of sidewalk salt and it says it is 100% sodium chloride. So I guess rust dyeing linen needs to be done in warmer temperatures.