Rent Shop Volunteer Join

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?

Share

Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
See a list of all Smarty Plants questions

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

 
rate this answer
Not Yet Rated

Thursday - September 05, 2013

From: Kimball, NE
Region: Midwest
Topic: Seeds and Seeding, Wildflowers
Title: Changing blooming patterns on sunflowers from Kimball NE
Answered by: Barbara Medford

QUESTION:

The common sunflower seems to be very prolific some years, not so much others. Is this weather related or cyclical?

ANSWER:

Did you know that there are 51 plants native to North America with the word "sunflower" in their common name? There are 39 in the genus Helianthus (sunflower) and, thank goodness, only one with the common name "common sunflower" in our Native Plant Database. Happily, this USDA Plant Profile Map shows that it grows natively in Kimball County, NE. The reason we get into all this is that the soils, climate and rainfall can easily influence how abundantly any plant blooms in any year, and we didn't want to handicap ourselves by not knowing exactly where this plant was being cyclical. Here, from our webpage on this plant in our Native Plant Database, are the growing conditions for Helianthus annuus (Common sunflower):

"Growing Conditions

Water Use: Medium
Light Requirement: Sun
Soil Moisture: Dry
CaCO3 Tolerance: Medium
Soil Description: Dry, disturbed clays or heavy sands.
Conditions Comments: Common sunflower spreads rapidly by seed, especially in disturbed sites. It has been shown to have an allelopathic effect on other plants. Many subspecies intergrade throught the species range. The cultivated giant sunflower is a member of H. annuus, derived through artificial selection."

Notice especially the line about "It has been shown to have an allelopathic effect on other plants." This means it protects its own territory by emitting substances to discourage competition from other plants. Because we could find no research-based answer to your question, we are going to make some suppositions. Like every plant, the sunflower is dependent on the weather (hot, cold, dry, wet) to thrive. When some of the numerous seeds put out by the sunflower (and not consumed by all the birds, insects and animals that love the seeds) in a very favorable place, it will first establish its dominance by trying to kill off all the other plants that like the same conditions. This will then permit it to make more blooms, drop more seed and take up new territory. In that sense, you could say it is cyclical. But if a year comes in which conditions are very bad for sunflowers, the other, less aggressive, plants may get a foothold and crowd out the sunflowers, so that would be seasonal.

 

From the Image Gallery


Common sunflower
Helianthus annuus

Common sunflower
Helianthus annuus

Common sunflower
Helianthus annuus

More Seeds and Seeding Questions

Lack of Fruit on Forestiera
March 17, 2013 - I have not been able to get berry production on my elbow bush. I have male and female plants. Is it possible to help with the pollination process? Thank you.
view the full question and answer

Starting Melochia Pyramidata from Seed
November 06, 2014 - Last year some Melochia pyramidata popped up in my yard all on its own. I was able to gather some (really neat looking) seed pods once they had dried out. I'm moving pretty soon and I'd like to grow...
view the full question and answer

Standing Cypress Plants in San Antonio, TX
June 26, 2013 - I purchased seeds for standing cypress 2 years ago and this spring they look beautiful. What is the best way to harvest the seeds? Also, will the current plants come back next spring or will I have to...
view the full question and answer

Comment on poisonous sweet pea plant from Kalama WA
October 29, 2011 - No question, comment only. I am aware of the story of Christopher McCandless (Call of the Wild)and the belief that he was poisoned by ingesting part of the sweet pea plant; however I am curious what ...
view the full question and answer

Golden groundsel plants or seeds for Bulverde TX
October 02, 2011 - Where can I find golden groundsel, plants or seeds?
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.