It’s hard to be rational about planting flower and vegetable seeds, with warm days making you think you waited too long to plant, and cool days making you think you have plenty of time.

Deal with your fickleness by watching blossoms on trees and shrubs. They respond to the general, rather than day-to-day, warming trend and, therefore, are good barometers of what to plant. For example, although apple trees do not bloom on the same date each year, when they do bloom, it means the weather finally has warmed enough to plant snap beans.

Forsythia blooms are the sign to plant the hardiest seeds. Crunchy radishes, tender peas, fragrant sweetpea flowers, and sunny poppies are in this category, as well as carrots, chard, parsnips, calendula, alyssum, cornflower, and baby’s-breath.

The next to bloom are juneberries, flowering quinces, and cherries. They give the signal to plant out cold-hardy transplants that have been growing indoors. Frosts will still occur, but small cabbage, broccoli, onion, snapdragon, salvia, pansy and larkspur can take it.

Frosty nights become fewer as clouds of white and pink apple blossoms blanket the rolling hills of orchards. This is also when lilac earns its keep, in the form of fragrant lavender or white blossoms. Quick on the heels of apple and lilac blossoms will be the creamy-white or salmon-pink dogwood blossoms, and the blooming white spires of horse chestnut. Although the air temperature might dip occasionally at this time, the ground will have sufficiently warmed to remain so.