You can rely on Bidens to thrive in the summer garden

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Image by Jaroslav Spanko from PixabayImage by Jaroslav Spanko from PixabayBidens is one of those summer annuals you can rely on to survive and thrive in the garden – they bloom all summer, love the heat, and are water-wise as well as disease and pest resistant.  Plant a couple this summer and you’re sure to add them to your list of favourite summer annuals for next year. Read all about growing these robust little plants below.

Bidens is one of those summer annuals you can rely on to survive and thrive in the garden, and all summer long, until the first frost, it will continually produce a profusion of yellow flowers that are held above the foliage on wiry stems. It grows vigorously, and has lovely, finely textured leaves. The flowers do not require deadheading to re-bloom, and this plant is known for its heat, wind, and drought tolerance – perfect for our sunny and hot South African summers.

Bidens ferulifolia was once known as Coreopsis ferulifolia and although it may have had a name change, it remains one of the most popular and best-selling summer flowering annuals around the world. Its sunny colour and casual style, combined with its ease of growth, led to this top performer receiving many plant awards, including the RHS (Royal Horticultural Society) prestigious Award of Garden Merit. It was also voted by Proven Winners as “Most Likely to Thrive.

Bidens is a genus of flowering plants in the aster family, Asteraceae. There are more than 200 species, with native types in far flung places like Mexico, The United States, including Hawaii, and Europe. In the United States these plants are considered a native species in every state except Wyoming. The common names include: beggarticks, burr marigolds, cobbler's pegs, Spanish needles, stickseeds, tickseeds, tickseed sunflowers, and black-jacks, referring to the fruits of the plants, most of which are bristly and barbed, with two sharp pappi at the end.

In South Africa we have the black-jack (Bidens pilosa) which is native to North and South America and was accidently introduced to South Africa and many other countries. Most sock-wearing school kids will be familiar with the black seeds that easily catch onto socks if you brush past the plant. In many regions the black-jack is considered to be a medicinal herb while in other places the plant is eaten.

The good news is that the commercially grown bidens varieties are sterile as they have been cultivated to avoid the sticky seed problem, and are therefore safe to plant in gardens. Because the plants don't waste energy on seed production, they produce more blooms for longer periods. Some older types can get leggy with loose growth, but the newer varieties have improved branching with tighter internodes, which means denser plants and therefore more blooms. There are a wide variety of selections available, and many have a spreading or trailing form while others grow to be more mound shape.

Bidens typically has blooms in yellow or orange, but plant breeders have introduced newer varieties which include pink, gold, and white blossoms. There has also been an increase in flower patterns and now you can find petals with brushstrokes and rings of colours, and with contrasting colours on the tips of the petals.

In South Africa only a few are available, including:

Bidens ferulifolia ‘Golden Empire’ has a unique, compact but upright growth habit, growing +-25cm tall and 25cm wide. It produces masses of single, extra-large, golden-yellow flowers.

Bidens ferulifolia ‘Tweetie’ has a compact, upright growth habit +-25 to 35cm tall, and 15 to 20cm wide. It produces large, double yellow flowers in profusion.

Bidens ferulifolia 'Pretty in Pink' has a mounded form, and grows to a height of +-35cm and spreads 25cm wide. It produces masses of single, extra-large, deep pink flowers that fade to creamy white at the tips.

Bidens 'Golden Empire' Picture courtesy Ball StraathofBidens 'Golden Empire' Picture courtesy Ball StraathofIn the Garden:

Bidens is one of those summer annuals you can rely on to survive and thrive in the garden, and they are excellent filler, companion, or feature plants. If you plant a couple in the garden this summer, you are sure to add them to your list of favourite summer annuals for next year.

Because of their drought tolerance bidens are an ideal choice for a low-water garden, or xeriscape application. They are also highly tolerant of urban pollution and will even thrive in inner city environments.

Bidens is so versatile in the garden, bringing masses of flowers continuously, and a fine and delicate texture to the garden composition with its lacy leaves. It’s the perfect choice for beds and borders, and creates a bold effect in mass plantings.

Combine bidens with other water-wise annuals and perennials for full sun. Good companions include: Angelonia, Calibrachoa, and the Blue Marguerite (Felicia). The yellow blooms of bidens make an elegant contrast with rich purple flowers, such as annual lobelia, petunia, vinca or verbena.

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Because many bidens varieties have a trailing or spreading shape, they're often used in hanging baskets, window boxes, and container gardens as a ‘spiller’ plant, or as ‘filler’ companion to larger plants in pots and planters.

Because most bidens varieties are highly attractive to butterflies and other pollinators like bees it is perfect for bee gardens, and if planted close to vegetable and fruit gardens it will attract valuable pollinators like bees to the crops.

Cultivation/PropagationBidens 'Pretty In Pink' Picture courtesy Ball StraathofBidens 'Pretty In Pink' Picture courtesy Ball Straathof:

Nothing could be easier than growing bidens, and hot temperatures don’t put a damper on their growth and blooming. With many of these plants being native to warm weather locales like Hawaii, Mexico, and Polynesia, it’s safe to say that they won’t mind a little heat and humidity!

The drought resistant quality of these plants also helps them to endure hot, dry conditions. However, if long spells of dry weather persist,and you want them to continue putting on a good show in the garden, it’s best to water moderately but regularly. Water young plants regularly, until they are established, and check your potted plants regularly as they dry out much quicker than those growing in garden beds.

In the extremely hot and arid regions of South Africa, and in the winter rainfall regions, they will require regular watering throughout summer to keep them looking at their best. In the subtropical and frost-free summer rainfall areas bidens can be grow as short-lived perennials, and in cold and frosty regions bidens is grown as a summer flowering annual.

Although bidens loves full sun, they will take some light shade. However, in too much shade the plants will not bloom well and can become ‘leggy’.  In very hot and arid regions some shade at midday would be beneficial.

Bidens can handle any soil as long as it drains well, so if your soil is clay and does not drain well, rather plant into containers. Because they flower so profusely, they need good, fertile soil, so adding a generous amount of organic matter like compost will get your plants off to a good start. For potted specimens a good potting soil will suffice.

As bidens are heavy feeders, try to feed monthly with a fertiliser for flowering plants to keep them producing well.  Feeding is especially important for potted plants, and using a slow-release fertiliser at planting time will save you a lot of time on feeding, as these types of products slowly release nutrients into the soil for you.

Deadheading isn't really necessary as the plant will continue to produces flushes of flowers all through the summer, but an occasional light trim will help produce a bushier plant.

Problems, Pests & Diseases:

Another wonderful plus for this robust little plant is that, if cared for correctly it has a lot of resistance to pests and diseases, reducing the need to spray in the garden. Pests such as the white fly, aphids or thrips can attack the plant, but these can be eliminated with strong jet of water or a suitable pesticide.

Warning:

Bidens ferulifolia has no toxic effects reported for people, dogs, cats, horses, birds, or livestock. However it is not intended for human or animal consumption.

It is wise to discourage pets from chewing on plants, and to always supervise young children in the garden.