After a heavy winter of snow, rain and frost, it is likely (particularly if your soil is lightweight) that some of the surface topsoil may have been washed away. This is particularly important if you have newly planted borders on a slope, or if you have climbers in small beds next to house walls.
This is a clematis which is planted in a narrow bed next to the house. The rootball which has been growing well for several years has been exposed, as the soil has been washed off onto the patio. It was quite easy for me to mound up new compost around this rootball, to make sure that it was once again buried several centimetres deep.
If your plants are on a slope, and the top of the rootball has been exposed, you will need to dig them up - preferably this month before growth starts, and to replant deeper.
I tend to cut mini terraces into a border if it is on a slope so that water can pool around the plant, -giving it a chance to drink, and also meaning that run off doesn't destroy the slope and expose the roots.
Apart from exposed roots drying out in the air, and killing the plant that way, - they also mean there isn't enough stability for the plant to reach full height - or with this Clematis, full flowering potential. So a wander around the garden with a trug of compost and a spade searching for roots that are showing, could be a lifesaver.