Clay Higgins, New Jersey

Solarization of Daffodil Beds

February 5, 2016

Categories: American Daffodil Society, Basal Rot, Bulb Information, Daffodil Enthusiasts, Diseases and Pests, General, Growing Daffodils, Landscapes and Naturalized Daffodils, Nematode, Planting

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When I was first introduced to “solarization” of daffodil beds back in 1998 the Brookside Garden curator that I was talking too said to use clear thin plastic and because it didn’t get hot enough in Maryland, to keep it on for 90 days hoping for about 30 total days of 90 degree “F” weather.

Down in NC were I am now, I have had several major Growers (not necessarily daffodil growers) state that the best method is to use Black Plastic to get the ground as hot as possible to kill both basal rot and nematodes.

Does anyone have opinions about which is best to use, 1) Clear Plastic to allow in the sun rays, or 2) black plastic to block the sun but to generate as much heat as possible?

I know the late Delia Bankhead had some opinions on the subject but I can’t remember what they are.

In Eastern NC I have found that by spreading our my beds so that are no longer raised beds (I use heaped earth and not planks, etc  to make my raised beds) by the end of the summer the beds are essentially dry and are like “sandbox” sand that kids play in.  However, that seems to be only moderately effective.


8 responses to “Solarization of Daffodil Beds”

  1. Mary Lou Gripshover, Ohio Mary Lou Gripshover, Ohio says:

    Clay, you can find Delia Bankhead’s article, “A Solar Solution,” in dafflibrary.  It’s in the June 2008 Journal.  Just go to  Then type in solarization in the greyed out box near the top right.  That wlll take you to it.

  2. Clay Higgins, New Jersey Clay Higgins, North Carolina says:

    Hi Mary Lou,

    I read the article, even though the link you gave didn’t work.  Instead I went to ADS home page looked up dafflibrary typed in solarization and it took me to the journal in June 2008.  I scrolled down to the Article.

    The article pretty well stated the obvious that I learned from the Brookside Gardens years earlier, however, as a member of the NC Master Gardeners I have attended several training classes hosted by major growers of bulbs and flowers in North Carolina and they keep swearing by Black Plastic.  The article specifically states the same as I thought by saying “Do not used black plastic.”

    I don’t want to give the names of the major growers business as I don’t want to create an issue.

    Anyone have any experience with using Black Plastic?



  3. Mary Lou Gripshover, Ohio Mary Lou Gripshover, Ohio says:

    Sorry the link didn’t work, Clay.  I’ll ask Mr. Wizard to check on it.

  4. Clay Higgins, New Jersey Clay Higgins, North Carolina says:

    What’s a bad link amongst friends!  You have helped me so many times before.  I’m just glad of the feedback as it allowed me to find that old article again.

    My only difference is that I don’t add organic matter, fertilizer, etc., until planting time when I take off the plastic and heap the beds back into raised beds.  I also give the tongs on my rototiller a bath in bleach water.  Guess I have to get back into it again.


  5. Larry Force, Mississippi Larry Force, Mississippi says:


    I have had no experience with this but believe the clear plastic would heat the soil up hotter.  Some gardeners use black plastic in their garden rows and plant the plants right through it, to conserve moisture and prevent weeds. If the soil got very hot it would kill the plants.  Anyway that’s my thought on the subject.

    Clay, after commenting above, I got on the internet and typed in soil solarization. There are lot of articles on it. U-Tube has some nice ones, ALL say use clear plastic, the black plastic will absorb heat on the top of the plastic but it doesn’t allow the sun and heat to get to the soil underneath enough to kill weed seed etc. You could try a small area of both and check the soil temperature and see which is more effective.

  6. David Adams, New Zealand says:

    Hi Larry and Clay,

    Maybe you have solved a problem for me. Thank you. I have small raised vegetable beds and have often covered them with black plastic for weed control with no effect. My theory was that black plastic would transfer the heat into the soil. The weeds loved it. Next time I will try clear plastic on the basis that the soil will heat through the plastic and the plastic will insulate the heat in the soil.

  7. Clay Higgins, New Jersey Clay Higgins, North Carolina says:

    Mary Lou, Larry & Dave,

    Thanks for all your comments.

    My problem is the long history of Tobacco farming in the area of NC where I live now.  The farming has caused several problems.  Working with the master gardeners and getting my soil tested I found that this area has a natural infestation of nematodes and basal rot.  The nematodes are most root knot and not eel worm.  Keep my daffodils alive has become a full time occupation.

    You leave bulbs in the ground for 5 or six years, here, without digging to take precautions and you lose them all the nematodes and basal rot.  Some of my best hybrids have gone that route.

    Thanks for your help,


  8. Joe Hamm, Pennsylvania says:

    Joe Hamm, Washington ,PA

    My experience with ‘solarazation’ has been good with Black Plastic… generating as much heat as possible is dual purpose…..kills weed seed and sterilzes the soil,,,, It is very difficult to achieve and maintain the heat

    My experience with clear plastic … the weeds love to grow,,,,,,here in Pennsylvania,,,

    Joe Hamm