Gardening Year

Phenology – Folklore or Science?

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Have you ever heard of phenology?  I hadn’t.  I’d never even heard the term before.  I read about it in a new gardening book and it sounded unscientific, even esoteric to me.   So I looked it up.  And what a relief – it’s proper science and used by – among others – the meteorological services. Much to my surprise, I learned that I’ve used and applied the findings of phenology many times in my own garden.  Most probably, you do as well.


What is Phenology?

There is a more or less simple definition of phenology:  it is the study of periodical, recurring and characteristic manifestations of development and behavior in plants and animals. To cut a long story short: plants grow and animals behave differently throughout the year. With the help of these recurring incidents the year is divided into phenological seasons.  This so-called phenological calendar helps to predict meteorological and climatic trends.  This is of importance to the agricultural industry because the phenological seasons include local variations which can occur independently from meteorological and astronomical seasons.  You, the avid garden blog reader, knows this frustration:  while your own garden looks like it’s still stuck in winter, other gardens out there are growing and flourishing.

black elderberry

So, how does it work?

Every germination, every flowering, every leaf shoot has its own characteristic time which depends on weather and climate conditions of a certain location at a certain time.  These conditions vary from year to year –sometimes, cherry blossom is earlier, other times it’s a little bit later in the year.  Nonetheless, it rings in the warm season of spring.  In Germany, for example, forsythia bloom marks the perfect date for trimming roses.  Like forsythia, there are a lot of indicator plants which help you to choose the right time for certain gardening actions.  But also the behavior patterns of animals can serve as indicators: the first butterfly, the first bee, the behavior of spiders and mosquitos – they all are messengers for certain climatic and meteorological circumstances.

plum bloom

The Phenological Calendar

As cherry blossom is an important indicator for spring in Japan, a lot of other appearances of flora and fauna mark the perfect time for certain gardening activities.  Unfortunately, I couldn’t find out if the same phenological calendar is applicable all over the world, but, following its definition, there must be similarities in all regions.  I will give you some examples of phenological indicators in Germany.  Of course, not all plants grow in all areas, so I invite you to write me and tell me which indicator you use in your region!

  • Early spring: First bloom of hazelnut or snowdrop.  Opens the new gardening season with all its activities like soil preparation, trimming of summer blooming shrubs or division of perennials.
  • “Erstfrühling” (something like first spring, if anyone knows a proper translation, let me know): The bloom of forsythia, cherry, plum, pear, blackthorn and maple.  Foliage of gooseberry and currant.  Germination of summer grains.  Leaf shoot of conker, birch, European beech and linden.  It’s now time for planting potatoes, seeding sugar beets and trimming roses, lavender and berries. Planting of kohlrabi and lettuce.
  • Full spring: Bloom of apple trees, lilac and raspberry. Leaf shoot of oak. Shoots of potatoes and sugar beets appear, winter grains grow. Time for laying lawn and planting potatoes.
  • Early summer: Bloom of black elderberry, amaranth, hawthorn, weeds and Turkish poppy. Winter rye blooms, other grains grow. It is time for hay harvest, seeding of annual summer flowers, carrots and broccoli. Earthing up of potatoes.
  • Midsummer: Bloom of summer linden and potatoes, ripeness of currants.  Time for harvesting grains and canola.  Trimming berry bushes after harvesting, seeding of perennial flowers and clone reproduction.
  • Late summer: Ripeness of early apple, plum and pear species.  Ripeness of rowanberry.  Bloom of heather and windflower.  Time for second hay harvest and trimming hedges.  Planting of autumn crocus, Madonna lily and strawberries.
  • Early autumn: Bloom of autumn crocus and ripeness of black elderberry and hazelnut. Time for harvesting pears and plums.  Laying lawns, planting spring flowers, seeding lamb’s lettuce.
  • Full autumn: Ripeness of oak, conker, walnut and quince.  Fall foliage of conker, European beech, oak, ash tree and Virginia creeper.  Leaf fall of fruit trees.  Time for harvesting late potatoes, beets and apples.  Seeding of winter grains and green manure.  Planting of rhubarb.
  • Late autumn: Leaf fall of oak and conker.  Germination of winter grains.  Planting of hedges and fruit trees.  Lawn repair.  The gardening season is coming to an end.
  • Winter: All leaves have fallen down.  Winter trimming of fruit trees.  In general, pause of vegetation.

potato plants

Become a Phenologist

The accuracy of the phenological calender depends on the amount of data which is collected. The more accurate it is, the better you can predicate your garden work on it.

When elm leaves are as big as a shilling,

Plant kidney beans, if to plant ‘em you’re willing.

When elm leaves are big as a penny,

You must plant kidney beans if you mean to have any.


In case there are no elm trees nearby, you can also check out the Plant-Phenological Online Database for all observations in Central Europe or the Earth Alive Website and National Phenology Network for phenological data from mainly the USA.  There you can also sign in as an observer, so get out into nature and take a notepad with you!

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