A Surprise Cross Pollination Experiment - Eva Varga

June 12, 201310

We attended Norway Day in May and enjoyed a variety of activities and cultural presentations.  One of the activities the kids took part in was painting a flower pot and planting a Petunia that they could take home.  Sweetie selected a white Petunia and Buddy, a deep purple (sadly I wasn’t able to get a photo of Buddy’s – he wasn’t happy with his painting and didn’t want me to take a picture).

petunia cross pollination

We brought the flowers home and enjoyed their blooms indoors for a short time.   Frustrated with the dirt spilling on my counter, I suggested the kids put their pots on the front porch.  Sweetie was careful to water hers regularly (Buddy, not so much) and as could be expected, hers bloomed again.  To our surprise, however, her blossoms were no longer white but striped with purple!  “Mom!  Look at my Petunia!  I think bees must have visited both mine and Buddy’s!  Isn’t this cool?”

petunia nature study

Cross Pollination

Petunias are flowering plants that belong to the Solanaceae family and are hardy to climates within planting zones 10 to 11. Even though these sun-loving plants grow flowers that contain both the male and female reproductive organs, also known as the stamen and pistil, they won’t self-pollinate. Pollination thereby must occur through insects or wind to transfer pollen from one flower to another.  You can also play the role of the insect and transfer pollen yourself.

  1. Select a healthy, freshly bloomed petunia plant. Lightly swipe your fingernail over the yellow pollen on the anthers inside one of the plant’s flowers — if the pollen sticks to your nail, the flower is ready to pollinate other flowers
  2. Look for the stigma that’s sticking out in the center of a petunia flower that you want to pollinate. Lightly touch it with your finger. If it’s glistening and sticky to the touch, the flowers are ready for pollination.
  3. Moisten a cotton ball with rubbing alcohol and swipe it over a pair of tweezers to sterilize them. Allow the tweezers to air-dry.
  4. Hold onto the parent petunia flower with your nondominant hand. Use the tweezers to grasp the base of the filament inside the flower. The filament is the thin stem that holds up the anther with pollen. Pull upward to remove the filament from the flower with the anther and pollen intact.
  5. Rub the anther over the top of the stigma of the receiving petunia flower so the yellow pollen adheres to it. Pollinate as many flowers as you like in this manner.
  • Alternatively to removing the stamen, you can swipe a small paintbrush over the pollen from the parent flower and brush this pollen on the stigma of the receiving plant.

petunia pollination

When the pollen from one flower is carried to the stigma of another flower they combine their genetic information (RNA) and their seeds should produce a hybrid of the 2 original plants.  The hybrid may not have obvious changes in its appearance because plants carry similar genes. If you want only plants with the same characteristics from year to year then simply save the seeds from your favorite blooms and plant the seeds next year.

hybrid  A cross between two parent plants that are from the same species but don’t look exactly like each other.

This discovery – while unplanned – was a fascinating opportunity for us to further explore the concept of pollination.  While some plants, such as peas, self-pollinate very well; others, such as Petunias, are structured in such a way as to assure cross-pollination.  If your children are full of questions and interested in further exploring cross-pollination, encourage them to set up an experiment to answer their questions.  For example:

Experiment :: What would happen if flowers that usually cross-pollinate were self-pollinated instead?

For this experiment consider using Wisconsin Fast Plants which carry out their entire life cycle in less than a month if grown under constant lighting.  The flowers of Fast Plants have long pistils and short stamens, which makes it difficult, if not impossible, for them to self-pollinate.  Once the plants set seed, wait for the fruits to ripen, then count the seeds in the fruits and examine their quality. Which plants set the most seeds: the cross-pollinated plants or the self-pollinated plants? Was there any difference in the size and development of the seeds? Try germinating the seeds from each set of plants, either on moist soil or moist paper towels. Is there a difference in germination rates?

Submitted to the Outdoor Hour Challenge Blog Carnival at Handbook of Nature Study.



  • handstitch

    June 13, 2013 at 3:26 pm

    Great, beautiful surprise it is. Great care taking, Sweetie 😀 Another thought came in mind was the acidic/PH level of water used.and/or plant food applied and released over time. I wonder…

  • Ticia Adventures in Mommydom

    June 25, 2013 at 3:07 am

    This is where I really wish I could keep plants alive long enough to achieve this experiment. It’d be so cool to see the results. Especially to me, gathering the seeds. I”ve never quite been able to find seeds, aside from the obvious ones of acorns and a few others.

    • Eva Varga

      June 25, 2013 at 3:34 pm

      To be honest, this happened for us quite by chance! It was quite a surprise but opened up a wonderful discussion. 🙂

  • harmonyartmom

    June 25, 2013 at 5:53 pm

    Really interesting! We may have to make this a new garden flower challenge. 🙂

    • Eva Varga

      June 27, 2013 at 12:03 am

      That would be great! My daughter wants to do it again (perhaps because it happened quite by accident for us).

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  • bmourit

    July 28, 2015 at 1:04 pm

    This wasn’t from cross pollination. Unless, of course, her old plant died off completely and was replaced by a new one without anyone noticing. Not likely. Sometimes the color suppressing gene in white bloomers becomes unstable over time and the original color from its pre-modified ancestors begins to reappear.

    • Eva Varga

      July 29, 2015 at 6:22 am

      I didn’t realize; thank you!

  • Ken Davies

    December 18, 2017 at 1:35 pm

    Hmmm, how interesting . . . I say this because I think I’ve seen the same thing happen with a miniature rose over time!!!

    • Eva Varga

      December 30, 2017 at 6:41 am

      That’s awesome!

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