Bidens

( BYE - denz )

At-A-Glance Information

These plants, which grow in climates around the world, have many common names, including Beggarticks, Black Jack, Burr Marigolds, Cobbler's Pegs, Spanish Needles, Stickseeds, Tickseeds, and Tickseed Sunflowers. The seed pods produced by these plants are bristly and barbed, easily sticking to the clothes or fur of passers-by for easy transportation away from the parent plant. Typically, these plants are prolific bloomers and can produce white, yellow, or pink flowers. These are smaller plants, reaching about 6-12 inches tall and wide at maturity. Use Bidens to border flower beds or in mixed plantings. These flowers also do well in pots and as accent pops of color throughout the garden. Take care when planting these flowers in the landscape, as there is some evidence that they are mildly toxic to humans.

Bidens Species and Varietals

The genus Bidens includes 230 species and is a member of the plant family Asteraceae. The genus name is derived from the Latin words 'bis' (meaning two) and 'dens' (meaning teeth), referring to the barbed fruits the plants produce. Bidens grows well in USDA hardiness zones 8-11 or Sunset growing zones 16-24 as a perennial, and can be grown in any zone as an annual. To find your zone, click here: Zone Map.

Bidens alba (Butterfly Needles, Spanish Needles, Beggarticks, Shepherd's Needles, Burr Marigold, Romerillo)
This short-lived perennial to annual species of Bidens is native to tropical and subtropical regions in North America, Asia, South America, and Africa. The leaves of this species are edible, and are consumed in their native range, where it is also used as a medicinal plant. Butterfly Needles form taproots under the soil and tufts of green foliage above, reaching up to 1-3 feet tall and 2 feet wide at maturity. Flowers are white to cream-yellow, and are a great nectar source for local pollinators. This species is considered invasive in many areas around the globe due to its rapid spread and ability to outcompete native plants.

Bidens amplectans (Wai'anae Koko'olau, Kokolau)
This endangered species of Bidens grows naturally in coastal and lowland dry habitats on the island of O'ahu, where they are threatened by wildfire and habitat loss. Stems on these plants can reach between 5 and 10 feet tall, and are topped with yellow flowers that bloom in spring through fall. These are short-lived perennials or annuals.

Bidens amplissima (Vancouver Island Beggarticks)
This annual wetland species is native to British Colombia and the state of Washington in the United States. These plants can reach about 4 feet tall at maturity and roots are fibrous. Stems are typically dark red to purple, though they are also seen in shades of green. Flowers are yellow and foliage is green; Leaves have serrated margins.

Bidens aristosa (Bearded Beggarticks, Western Tickseed, Showy Tickseed, Log-Bracted Beggarticks, Tickseed Beggarticks, Swamp Marigold, Yankee Lice)
Native to the central United States, this species of Bidens is an annual, and reaches up to 5 feet tall. These plants are great at attracting bees and other pollinators and have yellow flowers. This species is considered invasive in Maryland, Delaware, and Kentucky in the United States.

Bidens aurea (Arizona Beggarticks, Apache Beggarticks)
This species is found in Mexico, Arizona, and Guatemala, and has naturalized in Europe and South America. These annual herbaceous plants reach a bit over 8 feet tall in just one growing season, and produce yellow flowers with white tips on each petal. Flowers are also seen in various shades of cream and yellow, sometimes with striping or blushing of colors. Cultivars include 'Hannay's Lemon Drop' (hardier than the straight species with white-tipped yellow blooms), 'Royal Brocade', and 'Sunbeam' (with handsome branching structure; good for cut flowers). Arizona Beggarticks is considered invasive in Spain, France, and Portugal.

Bidens beckii (Beck's Water Marigold, Water Marigold, Beck's Beggarticks, Beckwater Marigold)
Native to Canada and northern areas of the United States, this species is a perennial herb that reaches six and a half feet tall when mature. These plants emerge from stagnant or slow-moving water; leaves above the water line are simple and lanceolate, but leaves on the stem underneath the water's surface are very intricately divided.

Bidens bigelovii (Bigelow's Beggarticks)
These plants are native to the southwestern and south-central areas of the United States and Mexico. Individual plants reach up to just under three feet tall at maturity, and produce white flowers with yellow centers in spring and summertime. Bigelow's Beggarticks prefer wetland environments.

Bidens bipinnata (Spanish Needles, Soapbrush Needles)
Reaching up to 60 inches tall in just one growing season, this species produces white or yellow flower heads in spring and summertime. These plants are native to Asia and North America, despite their common name 'Spanish Needles', which refers to the appearance of the long, thin seeds held at the end of stems after flowers have faded. This species can be invasive in certain regions including Europe, Asia, South America, and Africa.

Bidens cernua (Nodding Beggarticks, Nodding Bur-Marigold)
This species of Beggarticks is native to Eurasia and North America, and produces a 3 foot tall plant from fibrous roots. Flowers are typically yellow, and leaves are green, simple and opposite. Stems can be decumbent or erect, and are clothed with linear green leaves.

Bidens connata (Purplestem Beggarticks, London Bur-Marigold, Swamp Beggarticks, Purple-Stemmed Tickseed)
This species is widespread in its distribution across Eurasia, Northern Africa, North America, Australia, and on certain Pacific Islands. These annual herbaceous plants reach 80 inches tall in a single growing season, and produce yellow flowers in spring and summertime. They prefer to grow in marshes and other wet sites, and have purplish stems. Considered invasive in Europe, Eurasia, Africa, Australia, South America, and certain Pacific Islands.

Bidens cosmoides (Cosmosflower Beggarticks, Po'ola Nui, Ko'oko'olau)
This species is endemic to mixed forests on the island of Kauai'i, Hawai'i. Flowers are yellow, often seen drooping from branches, and have stamens that extend past the petals, giving the plant a tropical look. These plants are critically endangered, threatened by habitat loss due to invasive weeds and brushfires in its native range, and also by the drop in its main pollinator's (the Hawaiian Honeycreeper) population.

Bidens ferulifolia (Apache Beggarticks, Fern-Leaved Beggarticks)
This species is native to Mexico, and produces unique ferny foliage. Flowers are yellow and bloom in spring and summertime. These plants generally reach up to 18 inches tall, flower profusely, and are great for beds and borders in cottage gardens, rock gardens, or Mediterranean gardens. When grown in containers, stems will cascade over sides. Varieties include 'Blazing Star' (with orange streaks), 'Beedance Painted Red' (with salmon-tipped rays), 'Taka Tuka Red Glow' (with red and orange-flushed petals), and 'Marietta Gold Spark' (a low-grower with yellow flowers).

Bidens frondosa (Devil's Beggarticks, Devil's-Pitchfork, Devil's Bootjack, Sticktights, Bur Marigold, Pitchfork Weed, Tickseed Sunflower, Leafy Beggarticks, Common Beggar-Ticks)
These plants prefer plenty of moisture and sunlight, and are native to the Americas. These are annual plants, reaching between 8 and 24 inches tall and producing golden to orange flowers in spring and summertime. This species is considered invasive in many areas of the globe, including China, South Korea, and several countries in Europe.

Bidens mauiensis (Maui Beggarticks, Ko 'oko 'olau)
This species is native to the island of Maui in Hawai'i where it grows on coastal bluffs and amongst sand dunes. This perennial species reaches about a foot tall at maturity and produces succulent green foliage and orange to yellow flowers in spring and summer.

Bidens nudata (Cape Beggars Tick, Baja Tickseed)
This species is endemic to Baja California Sur in Mexico, and has a mounding habit, producing yellow flowers in November. These plants are drought-tolerant choices for water-wise gardens, and have gained popularity in recent years due to this quality. They are great, colorful additions to gardens, reaching about 35 inches tall at maturity. Can tolerate a wide range of soils as well as be situated either in full sun or partial shade.

Bidens pilosa (Cobblers Pegs, Hitch Hikers, Black-Jack, Beggarticks, Farmer's Friends, Spanish Needle)
These plants are native to the Americas, and have naturalized in many places around the world. They reach about 5-6 feet tall at maturity and produce white flowers throughout the year, blooming most profusely in summer and fall. These plants are commonly considered to be weeds, but also have useful medicinal properties. They are known to be invasive in tropical and warm temperate regions including areas of Africa (Kenya, Tanzania, Uganda), Asia (China, Japan), Australia, and the Americas.

Caring for Bidens

Plant your Bidens in full sun exposure in well-draining soil. These plants should receive between 6 and 8 hours of sun each day for best performance and flowering. Beggarticks can tolerate a wide range of soils, as long as they are well draining with a pH of between 5.5 and 7.0 (slightly acidic to neutral). If local soils are compacted, do not drain well, or are particularly poor in nutrients, make sure to amend the planting area with plenty of organic matter or compost before installing. Apply a thick layer of mulch around the base of the plant after installation, ensuring that mulch stays at least a few inches away from the stems. This will increase soil moisture retention, suppress weed growth, and maintain a constant soil temperature. Keep the soil evenly moist, especially during the flowering and active growing seasons. Water in the morning, and avoid watering from overhead, as this can cause issues with mildews and other fungi. Once established, these plants can tolerate short periods of drought. Wetland species, however, appreciate consistently moist or even boggy soils.

Provide plants grown in particularly warm climates with some protection from the intense rays of the late afternoon sun. If growing in a frost-prone area, take proper precautions to protect these plants during times of freezing temperatures by mulching around the base of the plant and possibly covering with frost cloth if necessary to carry it over the cold season. Fertilize plants yearly by applying organic compost around their base after pulling back mulch. Work compost into the soil, water it in a bit, and then replace mulch. These flowers are not heavy feeders, and will not require additional fertilizer to grow well. Deadhead spent flowers regularly to encourage more blooms to pop, and pinch back leggy growth to promote bushier growth and increased flowering. Deadheading will also discourage these plants from freely re-seeding in the garden and curb their invasive potential. Bidens are considered annuals or short-lived perennials, lasting for between a single and a few years in the garden before needing to be replaced. Their re-seeding capability, however, will ensure that these flowers will last for many years in the landscape.

Growing Bidens in Containers
Bidens can do very well in containers. Choose a pot with adequate drainage holes (to allow excess water to flow away) that is about two inches larger in diameter than the root ball or nursery pot. Fill it with a potting mix amended with perlite or organic matter to improve drainage and fertility. Apply a layer of mulch on top to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water regularly; Bidens flowers planted in containers will need more frequent irrigation than those in the ground.

Propagation

The easiest and most straightforward ways to propagate Bidens is by cutting or through harvesting and growing seed. To propagate your Tickseed Sunflowers, follow the instructions below.

Propagating Bidens by Cutting

Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. A good substrate for propagation of cuttings is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
In spring or early summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 3-4 inch long portion(s) of the end of a non-blooming branch just below a leaf node and strip all but the top two or three pairs of leaves. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone (optional), and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about three to four weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots.
Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new plant.

Propagating Bidens by Seed

Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. The best potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
Harvest your seeds. The seed heads on these plants are pretty easy to spot, they're left behind after flowers have faded. Once they have dried out and begun to split open, you can harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will begin to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 7-14 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.

Problems and Pests

Bidens plants can be pests in the landscape in certain areas; they are considered invasive around the world, including the United States. Check with local authorities before planting. The following pests and diseases can cause issues for Bidens plants in the landscape: