The Myth of Sunny Windowsills

After I wrote “Welcome Crocus!” a few days ago, I found myself thinking about the number of sunny days in February….6 out of 28.  That’s less than a fourth.  January had 12 sunny days out of 31.  A baby seedling on a windowsill would be stretching, stretching, stretching to search for sunshine on 41 days and only find light on 18.  And that’s assuming these are south-facing windows with no trees or buildings or overhangs or other obstructions that cause anything but full, brilliant sunlight on that windowsill during the day.  East and West windows only get sun half a day at most, and that’s just not enough for seedling health.  A seedling wants 8-12 hours of bright sunlight for good growth.  Window lr compressed  I’ve often heard people talk about growing on a sunny windowsill, and just took it for granted that it was a common practice.  Now, however, I wonder.  Are there really many windowsills that are truly sunny, or is it a false perception?  Does a cheerful, positive person with a sunny disposition mistakenly perceive that there is plenty of sunlight daily  coming through the window?  And conversely, does a gloomy disposition fail to note what sunshine is there?  Only accurate observation and recording will tell the true tale.   For instance, the above window in my living room faces east, but at 9 am it’s already losing what little sunshine there was.  And, it’s certainly not deep enough to hold many plants. Often by the time the morning haze has cleared, the sun has already moved too far to help plants in an east-facing window.  Window kitchen compressed  This west-facing window in my kitchen barely has room to hold a set of salt and pepper shakers and at 2 pm is still void of any sunlight.  Window blue compressed  Because of the Mansard roof, my home has lovely deep, broad windowsills upstairs so theoretically I’m blessed with good spots for seedling flats.  Not true.  There are no south-facing windows.  Most of the east ones are shaded by trees.  They are useful for wintering over tropical hibiscus like the one shown above, ferns, and other container plants and I’m happy for that, but for seed starting they are basically useless.  The window shown above faces east, and only the left side gets any sunshine.  In January and February the sun angles so that in all the west windows only the north few inches actually get sunshine for 2-3 hours before it sets, when the sunlight is actually already weakening.  Even the big bow window in the master bedroom only truly gets sunshine on the north end, but it’s enough to get amaryllis bulbs growing.  Window bow compressed  This likely explains why our grandparents waited to plant everything outdoors “once the weather has settled and the soil is warm.”  They had fewer windows, and without the modern R-factor of insulating windows available today, those would have been frost-covered, chilly places not beneficial to baby seedlings.  They really had few options for starting seeds early indoors, and few outdoors unless they created a hot bed with fresh manure.

We are lucky that there are efficient, inexpensive lights available for seed starting.  They can be used totally, or as supplemental lighting for windowsill babies on cloudy days or for those that don’t get a full day of sunshine because of location.  Even under-counter kitchen lights will help.  Just remember that it takes 2 hours of artificial light to equal 1 hour of real sunshine, and adjust accordingly.

So take a moment to really analyze those seedling flats sitting on a windowsill.  How many hours a month are they actually getting the light they need?  You may need to add some artificial light hours to compensate for “those sunny windowsills.”

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.
This entry was posted in Growing indoors, Indoor Growing, Seeding, Uncategorized and tagged , , , , , . Bookmark the permalink.

30 Responses to The Myth of Sunny Windowsills

  1. bcparkison says:

    And then you need heat…I did get a “grow ” light once but my house is pretty cool and seedling just didn’t grow well . If I ever do this again I will look into a grow heat mat too.

    Liked by 1 person

  2. Cortney says:

    We have south facing windows but they sills aren’t deep enough to grow anything of substance. Never mind the cats that would gleefully spread dirt everywhere and eat all the seedlings. But sills and cats not withstanding, I still don’t think sunny windowsills (at our latitude) are sunny enough to grow strong, happy, stout seedlings. Grow Lights it is! Great post by the way!

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  3. terrifortner says:

    I put mine on my ironing board in the only large window I have. It is also right above a heat vent so if it’s cold then that spot stays warm. The warm sunlight, when there is sunlight, and the fake warmth when there isn’t is what really gets my seeds sprouted.

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  4. Interesting post. Never really thought about this before. I just aim for a bright spot!

    Liked by 1 person

  5. I’m trying a grow light for the first time ever, for this reason. So far my little tomatoes seem about as leggy as before, but we shall see!

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    • carolee says:

      Remember to 2 hrs of artificial for every 1 hr of sunshine, so 16-18 hrs of light a day minimum. Also light needs to be 1-2″ from plant tops. At least with tomatoes, if they are tall, they can buried deeply and that is actually a good thing!

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      • Oh wow, I read 14 hours somewhere. Maybe I’ll bump that up by a few hours. My neighbor is already convinced we are housing aliens from the weird purple glow! Thanks for the tip.

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      • carolee says:

        I’ve never used the purple glow lights…always just the cheap shop fluorescent lights. The sun isn’t purple, so how does that work?

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      • I know, right? The one I bought was about $30 from Amazon, and I liked the idea that a) it has a timer you can set and b) it has a sturdy clip, so I wouldn’t have to hang anything from above.

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      • carolee says:

        I buy timers used for outdoor lights at the after Christmas sales for 60% off. They work fine, and since I don’t generally use my light stand until after the tree comes down, they get double duty. I buy at least one every year though, because it seems I always want to add more lights. This year I put fairy lights on the potager’s entrance for Christmas. They are still there because I really enjoy seeing them every evening!

        Liked by 1 person

  6. Valonia says:

    I live on a boat and so don’t have any window ledges. Due to our mooring location our windows face east and west. Last year’s seeds were a failure, but this year I’ve lined boxes with foil and have stood them on their side on a shelf under one of the east windows. I’m hoping that the foil will reflect all light down and onto the seedlings within. Fingers crossed they’ll grow this year!

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    • carolee says:

      I’ve used foil as a reflector, but never stood boxes on their sides. Should work though, I’d think. I’ve seen some of the boats in Amsterdam all filled with grow boxes and they were beautiful! Best of luck.

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  7. I’ve grown many things in furious abandon on a not-very-sunny windowsill, but I suspect this is more to do with the will-force of the plants’ inherent exuberance to get going than it being an ideal situation.

    I sew very much later than everyone else precisely because of this issue, and get sweaty and nervous around this time of year when everyone’s seedlings are coming along, and I haven’t sewn a thing!

    But I wouldn’t consider artificial lighting for all sorts of environmental reasons – and because I (perhaps neurotically) worry that pampering a seed won’t help a plant if it’s not destined to thrive in the environmental conditions of my location. And much as I admire certain beautiful or delicious plants, I am a mostly hands-off gardener, and that’s as true for seeds as for the final result.

    They have to deal with shade and clouds and dim light out in nature, I figure a seed’s raison d’être is to push through any kind of condition and just live. I’m not sure how much help it needs from me (or how much I want to give it) except watering if it’s particularly dry.

    But this does dictate the kinds of plants I grow.

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    • carolee says:

      That’s a well-thought out response. I guess I just view it differently…maybe because I’m a mother, and having seen how totally helpless a newborn is, I’m conditioned to tend all babies in need. Yes, I pamper my seeds initially, but they still have to survive and thrive through the reality of hardening off and then in the real world. Do what works for you, and grow what you like. I’d certainly be grumpy if someone told me what I could or could not grow, or how much attention I had to give each plant.

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  8. danibrown57 says:

    I liked this post, Carolee! I live in British Columbia’s dry Okanagan region – just moved there from the coast last June. This was my first real winter (it mostly rains all winter in Vancouver) and what a winter it was! In February alone we received record amounts of snow. I havent seen bare earth in my yard since mid-December. Lol, I think modern gardeners are tempted to grow on windowsills because of the amazing variety of seeds available to us now from all over the world. We must have them!

    Liked by 1 person

  9. Rach says:

    I just started growing my first pot of sunflowers! I do in fact have them on my windowsill but I’m worried because I live on the east coast we’ve been getting a lot of snow lately so they’re exposed to cold windows. What kind of artificial light do you recommend?

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    • carolee says:

      Unless it gets in the 30’s and too cold to germinate, they will probably be fine. I just use cheap “shop” lights, the 4′ fluorescent kind you can get anywhere, for plants that will be moved outdoors after a few weeks. If you intend to grow plants indoors all their life, then use 1 grow-light bulb and 1 cheap bulb and it will work fine. Best of luck!

      Liked by 1 person

  10. kmkat says:

    Back in the day I had some friends who lived in an early 20th-century apartment building in St Paul. I was always jealous of the deep, deep windowsills in the apartment in that building — a good 10″ at least.

    Liked by 1 person

  11. Good to know that it takes 2 hours of artificial light time to equal natural sunlight. Enjoyed your windowsill “tour.” Thank you!

    Liked by 1 person

  12. I have south facing windows but sills are only 2 inches deep and the sun does move so each window gets some but not for more than 1 to 2 hours.

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  13. Don says:

    Helen has been growing plants from lemon seeds on our South facing windowsill Carolee. Friends and family have been quite impressed to receive them as presents.
    Just a little bonus for her suffering with a bad flu a month ago and lemon n honey drinks were the order of the day …

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    • carolee says:

      South facing windowsills are a joy! Wish I had some. Love the idea of turning flu’s remedy into something wonderful..passing on a lemon tree is much better than passing on the flu!

      Like

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