Bidens spp.

As a rookie horticulturist back in the early 1990s, my first experience with bidens was positive, but unremarkable. I observed some hanging baskets with an amazing powerhouse of perpetual yellow flowers. I was told that it was bidens, also known as beggarticks or burr marigold.

While I appreciated the vigor, durability and showiness of these plants, I was familiar with many other yellow-blooming aster family annuals that could offer equal “pop.” At that point in time, I also learned that the associated common names referred to the tiny seeds that have barbs and hitchhike by attaching to fur or clothing.

Bidens weren’t a big part of my repertoire these last 25 years or so. However, my dormant appreciation for them was awakened after a trip to the California Spring Trials (CAST) in 2015 and visits to many trial gardens over the last seven years. I kept seeing amazing new bidens with novel colors and more compact habits. They are heading into a renewed and tantalizing prominence that should excite all of us that grow, sell, plant and maintain seasonal plantings. Bidens are extremely low maintenance, forgiving and suitable for beds, containers and hanging baskets.

Related closely to Coreopsis, the taxonomy for Bidens has been described as “chaotic” with an estimated 150-250 species. The focus of this article is primarily on the fern-leaf beggarticks (Bidens ferulifolia) and related hybrids. Native to Texas, Arizona and Mexico, this species is used primarily as an annual, although it is perennial in Zones 10-11 and may survive winters above 40° F. Traditionally reaching heights between 12-18 inches, bidens are long-blooming and carefree, which are immediate assets for the novice gardener. The flowers are rich in nectar and pollen, and the plants are ignored by deer, with very few insect or disease problems.

The needs of bidens are fairly straightforward. Full sun is a must and while drought tolerance is exhibited, a regular moisture regime along with rich soils and sufficient drainage is ideal. A little pampering goes a long way with this plant. Bidens are not pH sensitive. Incorporate a slow-release fertilizer at planting time or consider liquid fertilizer applications every three weeks during the growing season in the container or landscape.

The fine-textured foliage adds a light, airy texture that is the backdrop for the colorful blooms. Plants that become too leggy can be pinched, sheared or cut back severely as needed. Older forms may get a bit leggy and loose and benefit from this treatment, but most of the recent breeding has addressed this with the focus on compact forms with improved branching and tighter internodes, which equates to denser plants and more blooms. Some of the most compact varieties hover densely at 10 inches in height.

The five-petaled blossoms are up to 2 inches across and come in single, semi-double and fully double forms. There are myriad varieties out on the market with many selections being seed grown and others vegetatively propagated. The flower production for bidens is amazing for coverage and consistency of bloom. The constant flush of new flowering obscures spent blooms that fade and fall. In other words, they “bury their dead” and no deadheading is necessary. Many new forms are sterile, which results in more flowering. It is important to research and review the form, height and stature of select varieties as there are some subtle differences.

Evolution and revolution

The evolution of the color range for bidens has been the most noteworthy. While shades of yellow, gold and white have existed commercially for many years, it was the advent of flower petals with multiple colors and rich patterns that caught my eye. The color variability might include a different color center and petal tip or perhaps light brushstrokes of color or consistent color rings. I am still a fan of the yellow and gold forms with the modern varieties all performing well. Some of the double yellow/gold forms are mouthwatering. Admittedly, I haven’t used the white varieties often but have dabbled with some of the pink selections. It was the yellow and orange bicolor varieties that I first noticed and I continue to see varying degrees of yellow, orange, red and white in marvelous combinations. The increasingly intense red tones appearing in bidens is what I’m most excited about going forward. This genus has hit center stage as a primary role player in the garden.

With literally dozens of varieties out on the market, I would speculate that they are all excellent performers in the situations mentioned above. I have grown many of these new selections over the years and find them to be excellent performers. Container use is a slam dunk with bidens, and some selections are specifically promoted as semi-trailing which lends them to the hanging basket. There are some series of note out there including Bee Happy, Beedance, Timeless Collection and Taka Tuka.

My favorite golden varieties include ‘Golden Empire’, which is compact, upright and a heavy bloomer and ‘Goldilocks Rocks’ is my go-to selection for a basket or edge of container with its semi-trailing form and long bloom time. While there are many excellent orange/red bicolor bidens, my favorite continues to be ‘Blazing Embers’. The uniformity of the impactful flowers is striking. ‘Taka Tuka Red Glow’ has raised the bar has an amazingly rich, reddish-orange tint to the flowers and the subtlety of ‘Yellow Splash’ with a yellow center and white petal tips is beautiful in this semi-trailing selection.

My expectation of bidens being a solid performer out in the garden hasn’t changed at all in 30 years. However, the potential uses for these exciting new varieties should put bidens back on everyone’s radar as a garden ingredient with unlimited potential and popular appeal.

Mark Dwyer is currently the garden manager for the Edgerton (WI) Hospital Healing Garden after 21 years as director of horticulture at Rotary Botanical Gardens (Janesville, Wisconsin). He also operates Landscape Prescriptions by MD, a landscape design and consultation business. mcdwyer@zoho.com