When to Plant What According to Phenology

The Study of Letting Nature Tell You When to Plant

Working in a garden
Maginnis/ Twenty20

How do you know when to plant? Well, there are no guarantees, but if you let nature tell you when it's safe to plant seeds or put your plants out, you're probably on the right track. Nature sends certain signals that will let gardeners know how the weather and climate are progressing. There's a science devoted to this, called phenology.

Phenology is the study of the timing of recurring biological phenomena and their relationship to the weather. It is useful to gardeners, as a guide for when to plant. Weather can vary from year to year, but you can let the plants and animals tell you when it's time to start seeds. For instance, plant your peas when the forsythia blooms. It's no guarantee that you won't lose a few plants to a late frost, but phenology is a good guideline to keep you in the ballpark. You can even use it to be pro-active against pests.

Here's some basic phenological gardening advice. 

Phenology Clues 

Plant... When
Peas ... forsythia & daffodils blooms
Plant potatoes ... the first dandelion blooms or the shadbush flowers
... the shadbush flowers
Beets, carrots, cole crops, lettuce and spinach ... lilac is in first leaf
Beans, cucs and squash ... lilac is in full bloom
Tomatoes ... lily-of-the-valley are in full bloom
Corn ... apple blossoms start to fall
Cool season flowers (pansies, snapdragons...) ... aspen and chokecherry trees leaf out
Watch for... When
Eastern tent caterpillars to hatch ... crab apples start to bloom
Gypsy moths hatch ... the shadbush flowers
Squash vine borer eggs are laid ... when chicory flowers
Mexican bean beetle larvae hatch ... when foxglove flowers open.
Japanese beetles arrive ... when morning glory vines start to climb