University of Vermont Extension 
Department of Plant and Soil Science

Summer News Article


PLANT BREEDING FOR GARDENERS

 
Dr. Leonard Perry, Extension Professor
University of Vermont
 
           
Many new flowers have been created by home gardeners including those in such large groups as iris, roses, daylilies, and gladiolus.   Creating new selections at home through plant breeding is simple for many flowers if you know a few basic principles.

New flowers in home gardens can be selected from sports or mutations of existing plants, selecting new varieties that arise naturally through crossing by wind and bees, or by controlled “crosses”.  The latter is what “plant breeding” means.   The crosses refer to the controlled placement of pollen from one flower onto the receptive part of another, called the “stigma”.  The stigma is generally the thicker central structure in the center of flowers, often shaped like a tube or narrow vase.

To be successful, a cross must be made when the pollen and stigma are at the right stages.  Generally when the pollen is ready, so is the stigma.  The main indicator of this is when the flower is ready to open, or just opens.  The stigma often may be moist or sticky at this time in order to hold the pollen once transferred by bees, or by you.

The easiest way to transfer pollen is by a toothpick.  You’ll find the pollen on the “anthers”—the flower parts on very slender stalks called “filaments” that surround the central stigma.  Sometimes these may be on the sides of flowers as in roses or lilacs.  Just rub some pollen on the toothpick from one flower (the male parent) and transfer it to the stigma of another (the female parent).  Or you can pick the male flower and then rub its anthers onto the stigma of your female parent.

Timing is crucial, as once a flower opens, if both pollen and stigma are present it may go on and cross before your controlled cross.  To avoid this, just as the flower is opening or even before it opens on the female parent you’ve chosen, slit the petals and remove the anthers.  This process is called “emasculation”.  Then, to further avoid pollen coming from another flower not of your choosing onto this one, cover the flower with a small paper bag held with paper clip.  Remove the bag to make your own pollination, and then recover to avoid any further contamination by foreign pollen.
           
If your cross is successful, a seed will soon begin to from.  Harvest seeds when ripe, which usually is when the seed covering or pod begins to change color or turn brown.  Then sow as you would any other flower seed.  Sowing fresh seed often is best, and avoids many germination and dormancy problems.  Keep in mind it may take a year to several from sowing to bloom.
           
Be aware that flowers vary, with some only having a male or female part.  Many of our newer hybrids, especially of annuals, may be sterile or unable to be crossed if they don’t have the needed flower parts.  Petunias are often “male sterile”, having no viable pollen.  Others such as marigolds or chrysanthemums may be difficult to work with.  You may need a hand lens for some such as sweet peas, or tweezers to hold the filaments such as with gladiolus.  Daylilies and lilies are generally large and easy to work with, good plants to start your plant breeding. 
            

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