According to Mr. Google, phenology is “the study of cyclic and seasonal natural phenomena, especially in relation to climate and plant and animal life.” This is how you know when it’s time to plant peas (when forsythia and daffodils begin to bloom), or what bulbs will bloom with what. Sometimes it works, and sometimes, given climate change, it doesn’t.
So, one success this year is planting grape hyacinths to coincide with tulip sylvestris, an elegant swan-necked yellow tulip that I read about somewhere and planted for the first time last fall. 
These grape hyacinths are bigger and bolder than my older ones, and the bees love them.
Another success, at last, is ‘Sun Disc’ daffodils with Virginia bluebells. Here they are by the oak tree trunk, finally blooming at the right time.
Other phenological observations are that the cherry trees are beginning to fade, just as the redbuds spring forth. Here’s a cherry tree in my neighborhood several days ago: 
Alison’s two gorgeous crab apples are in full bloom right now. In my garden, there are tulips (the pink ones blooming with the Judd’s viburnum, just as ordered), daffodils, squills, ipheion, snowdrops, and more. It is an exuberant time in the garden.
Caroline's Garden and Travel Record 