Good gardeners are observant.  As soon as the weather begins to moderate, gardeners can be found studying their gardens for signs of life, watching the skies for “V’s” of birds flying north, and searching trees and shrubs for tiny leaves.  Why?  To gather information to make the decision to plant, or not to plant various crops.   forsythia alone  Traditionally, the first forsythia bloom tells us to plant peas.  Observe carefully though.  I’ve seen forsythia blooms over a week earlier in town, and almost two weeks before mine on a neighboring farm where it grows on the south side of a big concrete silo.  Each location is a micro-climate, so just seeing them as you venture about may not mean the same conditions are right in your garden.

lilac  When the lilac blooms it is time to plant beans, cucumbers and squashes.  While this might just sound like advice from the “Old Farmers’ Almanac” it is actually termed “Phenology,” the study of the relationship between climate and the life cycles of plants and animals.  In this time of changing weather patterns, a working knowledge of phenology is probably more valuable than the old lore of “Plant potatoes on St. Patrick’s Day” or any other task linked to a calendar rather than actual conditions.

Long before there were stacks of gardening books and blogs, long before there was a Weather Channel, gardeners watched for signs of growth in the plants and animals around them to help determine when it was safe to plant valuable seed.  Lives depended upon their success and knowledge.  There are some scientific basis for the success of phenology-based crops.  The first is soil temperature, because some seeds will not germinate until the soil gets to a certain warmth.  I don’t need a soil thermometer to tell me when it’s safe to plant out tomatoes.  I just need to see borage volunteers emerging in the potager’s interior border.

In addition to planting times, phenology is used to determine good  times to transplant, harvest, or to implement insect controls.  When the strawberries bloom, I know I need to start spraying Bt on cole crops to prevent caterpillars destroying the young transplants.

Other phenology indicators are when the lilac begins to leaf, plant beets and carrots, and direct seed second round cole crops.  Plant potatoes when the dandelions begin to bloom.  When white oak leaves are the size of squirrels’ ears it’s time to plant corn.  It’s safe to transplant eggplants, melons and peppers when the bearded iris bloom.Crocus 2-26-18 compressed Crocus photo taken last year…there’s nary a sign of them yet!

With over 50 years of observation, and the last 26 here in north central Indiana, I’ve fine-tuned the phenology to fit my garden’s conditions.  The first crocus (which in the past 4 years has ranged from Feb. 17 to March ??? since we’re still waiting!) means I plant onion sets, shallots, snow peas, shelling peas, chinese cabbages, kale, spinach, arugula, lettuce, potatoes, mustard, chervil, coriander and dill.  The first dwarf iris blooms means I can set out all the hardened off violas into the potager’s main paths.  A daffodil opening indicates it’s safe to plant carrots, beets, kholrabi and hardened leek plants.  When the peonies are 4″ tall I set out hardened cole crops (broccoli, cabbages, cauliflower, etc.)  I once tried to push the broccoli and cauliflower into an earlier group, but they never head properly, so I’ve learned it’s worth a bit of a wait.  It is also usually a safe risk to plant “Royal Burgundy” beans, which can withstand cooler, wetter soils without rotting.  When my lilac blooms, the earliest cold-tolerant tomatoes like “Polbig” can be set in the ground, but the rest must wait until volunteer borage seedlings appear.

Do you use observations to tell you when to plant?  If so, what are your favorites?


About carolee

A former professional herb and lavender grower, now just growing for joy in my new potager. When I'm not in the garden, I'm in the kitchen, writing, or traveling to great gardens.
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14 Responses to Phenology?

  1. bcparkison says:

    I have done some of this in the past. People long ago just knew what to do when, There really is something to this knowledge.

    Liked by 1 person

  2. Stevebfineart says:

    there is a certain amount of truth still in phenology, although in todays world we have things like greenhouses, heated seed trays and mats so one doesn’t have to be too reliant upon storm and tempest not wiping out ones crop, enjoyed the read, thank you.

    Liked by 1 person

  3. I stick by the old wisdom “When gorse is out of bloom, kissing is out of season.”

    Liked by 1 person

  4. Jo Shafer says:

    Wow, Carolee! I must copy out these “dates” in my garden journal for good reference.

    Liked by 1 person

  5. Helen says:

    I’m interested in your observation that you feel you can plant out tomatoes once you see the borage volunteers. I’ve had borage volunteers overwintering but no way would I plant out tomatoes yet. That’s because there could just be a frost which killed the tomatoes. Maybe though I could use a sacrificial specimen and see how it goes!


    • carolee says:

      Of course our borage never survives the beginnings of winter here, and their hard seed coat takes a good amount of warm soil temps to crack. I’ve never lost a tomato if I wait for the borage….but keep in mind that’s the EARLY, cold tolerant tomatoes like Polbig that I’m talking about…I don’t plant Big Boys or Romas or other “regular” tomatoes that early.


  6. Very informative Carolee! I learn so much from you. Thank you for sharing your years of knowledge and experience!

    Liked by 1 person

  7. Island Time says:

    Wow! What a lot of great planting tips and information. Thank you so much! Phenology is a new word for me, though just yesterday i was tring to recall something you wrote in the past, I believe, about the forsythia blooming, or when it is time to prune the roses, or something along those lines. Now i am going to jot down these “rules” so i too can make the most of my collection of garden seeds this late, and frigid, spring. Thank you!


    • carolee says:

      You are entirely welcome. I find it make me more observant in my own gardens, but as I am out and about as well. It’s interesting to note where things bloom earlier than mine, and where things bloom later right in my own neighborhood. I’m moving my hellebores this year…everyone else’s bloom WAY before mine!

      Liked by 1 person

  8. Ann Mackay says:

    Very interesting – makes me want to keep notes of everything that’s going on in my garden to see how these things tie in together. Great to see that old and valuable ways are not being lost! 🙂


    • carolee says:

      Do keep notes…it’s fun to see how some years start differently date-wise but eventually it all catches up. I do prefer the years when the early blooms come bit by bit, rather than it staying cold, cold, and then BAM! everything blooms at once, which may be the case this year.

      Liked by 2 people

  9. Green Magick says:

    We do use similar local observations, and they work! Unfortunately, we are still waiting for two feet of snow to melt. Even when the local snow melts, old timers here start planting cold crops when the snow on a particular distant mountain disappears, usually around Easter. 😊. But the moment our snow is gone, we will see garlic shoots, Elderberry buds, and, and, and! Can’t wait!

    Liked by 1 person

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