Just two years ago I took a photo in front of my azalea in full bloom in March, the past two years this same azalea has not bloomed until May.
You may have heard the saying, "when the forsythia bloom it is time to prune (roses, specifically)."
For centuries farmers have taken their cues from nature. Watching these natural indicators has evolved into the use of soil themometers, greenhouses, and cold frames to extend the natural growing window.
One of the first things I learned after moving from Zone 8 to Zone 5 was that I now have 100 fewer growing days. Wow. That has a lot of impact on seed selection and planting dates, as well as being more aware of days to maturity.
Peas, onion sets and lettuce follow forsythia bloom, whether you are watching the bloom or the soil temperature for germination.
Beets, carrots and chards follow your daffodils. And plant your bush beans following your apple blossoms. Peppers and eggplant may be transplanted out with your Iris blooms.
What cues from nature do you follow in your garden?