Mexican Sunflower-(Tithonia): To Plant or Not To Plant

(Picture of Tithonia by Jeff Schalau)

Sharing is fun, especially when it comes from the garden. Of course I enjoy sharing produce with others, but my real love is in sharing flowers. It is an activity I can do with my wife that brings joy to our family, friends, and neighbors. I plant and raise the flowers, and my wife arranges them in mason jars to give away to whoever needs them. Maybe they just had a baby or just lost a loved one. Maybe they are sick or just had surgery. Or maybe they just need a pick-me-up or something to smile about. My wife and I were blessed to share our flower arrangements with 47 people last year.

I am always looking for new flowers to share. One flower I started using two years ago is Tithonia Rotundifolia of the Asteraceae family, commonly known as Mexican Sunflower. It has much the same open growth habit as of regular sunflowers. It grows over 6 feet tall and has vibrant orange/red, 3-to-4-inch flowers with a yellow center. They are beautiful in arrangements.

This year I hoped to still use Tithonia, but first I wanted to check out the allelopathic detriment Tithonia may have on other plants around it. The 2024 CCMG manual glossary defines allelopathy as: “The excretion by some plants’ leaves and roots of compounds that inhibit the growth of other plants.” 

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.

Idaho Native Flowers

When you hear the phrase “native flowers”, what do you picture? Maybe a landscape full of beautiful, colorful, and beneficial flowers? Or does your mind conjure up an image of valueless, unattractive, and dull flowers? In this article, I will present three native flowers to consider planting in your landscape or garden: Common Yarrow, Wild Blue Flax, and Common Camas, emphasizing reasons to plant Idaho native flowers.

Yarrow (Achillea millefolium) is a perennial that grows early spring and blooms through mid-summer. It has long leaves that appear fern-like and flowers that range from white, yellow, pink, or red. Yarrow was a food source in the 17th century and North American tribes used it to treat many ailments. Its rapid growth from seed and rhizomes encourages spreading. It also tolerates many conditions and soil types and is relatively pest-free. Because it attracts beneficial pollinators and is a food source for big horn sheep, deer, sage grouse, and their chicks, Yarrow seed has been added to other nature seeds to rehabilitate disturbed sites along roadways and parks and is very well suited for xeriscaping. Yarrow is also good for composting and a good companion plant to tomatoes.

Wild Blue Flax (Linum lewisii) is an annual which blooms from May to June. It produces concentrations of small, cheery blooms balanced on thin green stems. Flowers last a day and are replaced with fresh blooms of light blue, blue, yellow, and red. Blue Flax produces a lot of seeds and reseeds itself. It is adaptive to most soil conditions and is drought tolerant with minimal problems with disease. It is a food source for deer, antelope, and birds and may provide protective cover for small animals and birds. Blue Flax is also valued by land management for helping with erosion control.

Common Camas (Camassia quamash) is a perennial herb grown from an edible bulb in the Lily family. It blooms from April through June and produces many seeds. A single plant may live from fifteen to twenty years. Flowers range from light to deep blue. Camas is a food source for elk, deer, moose, and gophers. Common Camas is still considered to be one of the most important (root) foods and medicinal plants of the North American Indigenous population. The bulbs are usually harvested after flowering in the summer. It is recommended that people use caution when identifying and harvesting Common Camas so as not to confuse plants with Death Camas which can be toxic if eaten.

Native flowers are not invasive, but rather protect the biodiversity that supports our local ecosystem maintaining land development and conserving resources. Native plants are almost effortless to grow and nurture. Native plants are masterfully adapted to our unique environment, saving time and money. Along with providing beauty and benefits, with some experimentation and education, you could format your landscape for year-round attraction. For these reasons, consider planting Native flowers and help support and safeguard Idaho’s legacy.

Start Your Garden Journal NOW!

A gardening journal is a perfect place to organize and

store all of your garden-related information that will guide you in making future decisions about the plants you choose to grow, how to combat any nutrient deficiencies and pest invasions/disease problems which you encountered, and dreams about future landscape designs for your space. There is no right or wrong way to keeping a gardening journal; it is simply a personal horticultural record of your observations as well as yours hopes and dreams for your garden. 
There are as many different formats or styles of journals to choose from as there are gardeners. Based on your personal preferences, you could simply use a blank hard-cover composition book, a spiral notebook, a graph paper notebook, a scrap book, a three-ring binder with plastic dividers and pockets for seeds, a custom designed disc-bound notebook or even a digital format (there are many apps to try!). Whatever system you select, make sure it is easy and convenient for you to use.

The contents of your garden journal will depend upon what you find interesting or useful in your garden; it can be a detailed scientific collection of information, a creative expression of the beauty in your garden or anything in between. The scientific gardener could include charts and graphs to record temperatures and fertilization schedules. The artistic gardener could add pressed flowers or leaves and artwork. There are several recommended categories that ought to be included in your garden journal. Recording your hardiness zone and the first and last frost dates are critical to planting the right plants at the right time in the right places.

Recording the dates of direct sowing, transplanting, blooming, and harvesting times will also be quite useful. Creating a map will help you remember the varieties of plants you planted and their locations. Some other suggested topics you may want to include are the sunlight patterns during the growing season, unusual weather and temperatures patterns with dates to help you determine best planting times, a maintenance and fertilizing schedule, any diseases or pests your plants encountered along with the most effective treatments, the soil quality, seed inventory lists, and your goals for the next year. 

Keeping a garden journal will help you celebrate your successes, learn from your mistakes, and be prepared to deal effectively with gardening issues. By simply observing and recording the dynamics of life in your garden, you will create a powerful resource for future successes in your gardening journey.