Phenology – The Science to Help You Plant Your Garden

  • Post published:05/05/2021
  • Post comments:2 Comments
These lilacs are just beginning to bloom – past the date of a mouse’s ears, but almost time to plant beans

Phenology is the science dealing with the relationship between climate and the recurrent natural events in relation to seasonal climatic changes. That may sound difficult to understand, but those who watch for the arrival of migrating birds, or the opening of flower buds are studying phenology. Centuries ago the Chinese did not know about the science of phenolgy but they did understand that spring was recognized by plants before the farmers did.

Eventually farmers around the world learned to watch for the signs that said it is time to plant. I  remember the first time I was told that when a lilac leaf was as big as a mouse’s ear it was time to sow peas and lettuce. This year, in my tiny vegetable garden I did plant lettuce when the lilac leaf was as big as a mouse’s ear. I was thrilled to see the little seedlings greet the sun. The dandelions blooming in my lawn told me it was time to plant beets and carrots, as well as lettuce. I planted beets.

Treasure your dandelions. They feed the pollinators

Lilacs have a lot to say about when it is time to plant other plants. When the lilac is in full bloom it is time to plant beans, and when the lilac flowers have faded it is time to plant squash and cucumbers.

Of course, it is not only lilacs that give advice to the gardener. When daffodils begin to bloom I’ll know it is time to plant peas and when oak leaves are as big as a squirrel’s ear it is time to plant corn. Apparently little ears can tell you a lot.

The dogwood trees in our neighborhood are just beginning to bloom but when they are at their peak bloom it is time to plant tomato seedlings. Or you could check the lily-of-the-valley flowers. They also know when it is time to plant tomato seedlings.

There are problems in the garden and the plants help here, too. If the crabapple and wild plum are at budbreak it is time to watch out for the eastern tent caterpillar. Steps must be taken The eastern tent caterpillar is not a friend.

The study of phenology has been useful for thousands of years, but it was not until 1736 in England when Robert Marsham   began gathering information about the seasons and birds, insects and plants – began to use the word phenology.  In 1875 the Royal Meteorological Society  included  this science and began keeping records of those creatures.

For more about phenology  BUDBURST, a project of the Chicago Botanical Garden will provide information and interesting projects for you.  (

This Post Has 2 Comments

  1. Jeane

    I’ve been watching my forsythia for years- when it blooms, I plant the lettuces and other cool-weather greens. I learned about the lilac markers, but didn’t know the lily-of-the-valley one. According to that, I could plant out my tomatoes this week! although we still have some nights in the forties.

  2. Pat

    Jeane – When we moved to our new house 5 years ago we had no idea we could make a vegetable garden there, but the pandemic pinched us. I am just starting to plant my cool weather plants. You sound really skilled.

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