(Picture of Tithonia by Jeff Schalau) |
Jeff Schalau, an agent of agriculture for the University of Arizona, reported, “In my garden this year, the Mexican Sunflower (Tithonia rotundifolia) looks to have had serious allelopathic effects on my adjacent lettuce bed. The lettuce plants within four feet of the Tithonia are noticeably stunted.”
(Picture of the affected lettuce) |
(Plot growing the same lettuce seed but isolated from Tithonia) |
Good thing I don’t grow lettuce. Although Tithonia can have negative effects on other plants (Schalau also mentions legumes and cereals), it appears that it is only within close proximity. In my own garden, beans and tomatoes were planted about 10 feet away from the Tithonia but produced great, as did chard, peas, and peppers.
So of what benefit is Tithonia? As the North Carolina state extension Gardener Toolbox discusses, one of its ecological positives is its role as a pollinator. It is commonly used in gardens to attract butterflies, hummingbirds, songbirds, and other pollinators. I remember in my garden last year I had to pick them early each day before the plants were covered with bees.
Now that I know Tithonia better as a great pollinator and understand the precautions needed to decrease allelopathic effects, I will invite this beautiful flower back into my yard. Who knows? Maybe my wife and I will share 50 arrangements this year.