There’s been a slow but steady revolution going in the world of annual flowers. Thanks to hybridization and selection, the quality of annual flowers just keeps on improving, year after year. And now we’ve gotten to the point where deadheading (pruning out faded flowers) is often no longer necessary. One huge task less for home gardeners to carry out!
How Things Have Changed!
It’s hard to even remember what the wild ancestors of today’s annuals even looked like. Often they were sparse plants with only a few short-lived flowers. Today, most annuals are not only dense and highly floriferous, they bloom repeatedly throughout the summer.
The result of this constant improvement is that one of the basic tasks of maintaining annuals — deadheading — is less and less necessary. Now all most modern annuals need is watering when the soil dries out and a bit of fertilizer. You simply don’t need to pinch or cut off those faded blooms.
Oddly enough, many gardeners keep on deadheading: they haven’t noticed the sea change. And you wouldn’t notice, would you? If you always deadhead your annuals, how could you know the task is now a waste of time? So this summer, try it and see. Don’t deadhead and just watch the results. You’ll be blown away … at least, with most annuals (there are still a few that do need deadheading).
The Whys and Wherefores of Constant Bloom
Why would a plant that originally bloomed for 2 or 3 weeks in the wild now be able to bloom for 3 or 4 months in a home garden? This is largely due to the work of hybridizers. They work in the background and get little credit for their work, yet they’ve been developing annuals that need less care for well over a century.
And they’ve found different paths in their search for nonstop bloom.
Sterile Varieties to the Rescue
Some of today’s nonstop annuals are sterile varieties. That may not sound like a promising idea, but it is.
In nature, plants bloom to produce seeds that guarantee the survival of the species, thus ensuring the next generation. By deadheading a plant repeatedly, especially an annual (it has more to lose if it doesn’t produce viable seeds, since it lives only one year!), it’s often possible to force it bloom again and again. But if the plant is naturally sterile, so that the flowers it produces don’t result in viable seeds, very often the plant will bloom again and again, striving vainly to produce seed, without any effort on your part.
Here’s a recent example.
Most gardeners know sweet alyssum (Lobularia maritima), a short, cushion-shaped annual with abundant but tiny fragrant flowers. It’s a charming plant, but not very long blooming. It normally flowers beautifully for about 5 to 6 weeks, then stops and focuses on seed production. If you want to see it rebloom, you have to deadhead (remove the faded flowers) and in this case, it’s radical surgery: you need to shear the whole plant back to about 2 inches (5 cm) high. If you do that at just the right time, the plant will produce new flower stems and start to bloom again … in the ultimate hope of producing seeds. These labor-intensive sweet alyssums are still widely available today.
About 10 years ago, hybridizers in Israel discovered that if they crossed the annual sweet alyssum (L. maritima) with a shrubby species from the Canary Islands, L. canariensis, this gave a sterile plant a bit taller and certainly much wider than annual sweet alyssum, but with the same abundant, highly perfumed flowers. However, these hybrid sweet alyssums are sterile: they produce no viable seed. The result is that the plants just keep on blooming, through the summer and well into fall.
These hybrids, including the Princess® series and the Knight® series, will often bloom from May until Christmas in the Northern Hemisphere: now that’s flower power! In mild climates (zones 9 to 11), they will literally bloom, massively, 12 months a year!
There is, however, a price to pay for this major development. The old-fashioned annual sweet alyssum can be produced cheaply from seed, but the new hybrids, being sterile, can only be grown from cuttings or tissue culture. That requires more handling and, as a result, they cost more. However, you can take cuttings from hybrid alyssums and grow them indoors over the winter (where they will bloom more modestly, unless you have really great light), and thus recuperate your investment.
Better Performance Through Selection and Hybridization
Prolonged blooming through plant sterility is, however, only one possibility and indeed, a fairly limited one, at least among annuals. More often than not, prolonged flowering in annuals has come about simply from selecting the very best varieties and crossing them together.
Generation of gardeners having been taking notice of annuals with extra flower power and saving their seed for the following year. Even in a home garden, if you do this for a few years, you’ll see a serious improvement in the plants’ performance. Imagine when professional horticulturists, with a specific goal of improving results, get involved! Well, annuals first became popular as bedding plants in Victorian times, so horticulturists have had over a century to work on improving them … and they’ve come a long, long way!
Hybridizing comes into play when they cross two long-blooming varieties together. In most controlled crosses, some of the progeny are almost always better, longer bloomers than either parent. Keep that up for a century and you can imagine it can really turn things around!
Of course, horticulturists have been looking for all sorts of other things besides prolonged bloom: bigger flowers, new colors, double blooms, denser plants, improved scent, disease resistance, etc. Still, flowering periods have been gradually increasing over the years and many commonly grown annuals have now turned the corner and are nonstop bloomers. The ultimate goal in low-care annuals is a plant that will bloom abundantly from May to September/October while requiring no deadheading, and that goal has been largely reached with many annuals.
The most recent plant to switch to the “no-need-to-deadhead” category is the petunia. And that’s great news, as pinching out all those faded flowers on a petunia, with its stems that are so disagreeably sticky, has never been a lot of fun.
Petunias that bloom nonstop without deadheading have been on the market for about 5 years now and are beginning to push the old varieties towards the exit. Sometimes you’ll suddenly see an old favorite with the word “Improved” or “Select” tacked on to its name: that could mean a lot of things, but these days, in petunias, it generally means no need to deadhead. In popular series, like the Supertunias®, which used to need a serious midsummer cleanup, older varieties are simply replaced by newer ones that don’t need deadheading.
Before buying a petunia, ask the seller for a variety that doesn’t need deadheading. Why would you buy anything else?
An additional factor to consider in annuals, besides continuous bloom, is the ability of the plant to dispose of its old flowers—or at least to hide them from view—, otherwise even if it did bloom nonstop, you’d still have to deadhead just to at least remove at the browning petals. And that would be counterproductive. Most modern varieties of marigold (Tagetes patula and T. erecta), for example, do bloom nonstop all summer and have had that capacity for over 50 years. Theoretically, they don’t need deadheading, but … the masses of browning petals on the old flowers still disfigure the plant, making you feel like you really should get out there and remove the faded flowers.
But more and more annuals are now “self-cleaning”: their petals fall off all by themselves after the flower stops blooming. Remember the old garden pelargonium (Pelargnonium x hortorum), where a mass of brown petals accumulated over time if you didn’t cut off the dead blooms? Well, that’s no longer true: most modern varieties are self-cleaning. And many, many annuals now fall into that category. Hybridizers of marigolds (Tagetes, mentioned above) are still trying to develop self-cleaning varieties, and I’ve heard that progress is being made … there is nothing yet on the market.
Without being truly self-cleaning, several modern nonstop bloomers do at least hide their fading flowers: not by dropping them, but rather by outgrowing them. Either the plant gets slowly taller, hiding the faded blooms, or the flower clusters are indeterminate, constantly sprouting new blooms at the tip and on the outside, thus hiding the dead flowers inside the cluster from view. This is the case with most modern feather celosias (Celosia argentea plumosa), for example. With these plants, therefore, deadheading it no long necessary either. Why bother removing faded flowers if you can’t see them?
Why deadhead for nothing! The following annuals offer varieties with self-cleaning, nonstop bloom: exactly what a laidback gardener needs!
- Ageratum x Artist® (hybrid ageratum) — new flowers hide faded flowers
- Angelonia angustifolia (angelonia)
- Anisodontea (cape mallow)
- Begonia (begonia)—most modern varieties (Solenia, Unbelievable, Big, Dragon Wing, etc.) are everblooming and self-cleaning
- Bidens (bidens)
- Browallia (browallia)
- Callibrachoa (million bells)
- Catharanthus rosea (vinca, Madagascar periwinkle)
- Celosia argenta plumosa (feather celosia) – new flowers hide faded flowers
- Cleome (cleome)
- Diascia (diascia)
- Euphorbia hypericifolia Diamond Frost® and others (annual euphorbia)
- Impatiens (Impatiens)
- Lantana (lantana)
- Lobelia x Lucia ® and Laguna® (hybrid lobelia)
- Mercardonia (mercardonia)
- Mirabilis jalapa (four o’clock)
- Lobularia x (hybrid sweet alyssum)
- Nemesia (nemesia)
- Osteospermum Soprano and Symphony series (African Daisy)—new growth hides faded flowers
- Pelargonium x hortorum (garden geranium)—older varieties are not always self-cleaning
- Pelargonium interspecific (hybrid geranium)
- Pelargonium peltatum (ivy geranium)
- Petunia (petunia) — modern varieties
- Phlox drummondii Intensia® series (annual phlox)
- Plectranthus scutellaroides (coleus): modern varieties only flower at summer’s end, allowing the foliage to remain in the spotlight
- Portulaca (portulaca)
- Salvia splendens Ablazin® and Saucy® series (scarlet sage)
- Scaevola (scaevola, fan flower)
- Sutera cordata (bacopa)
- Torenia fournieri (wishbone flower)
- Tropaeolum majus (nasturitum)
- Verbena x hybrida (hybrid vervaine)
- Zinnia Zahara and Profusion series (hybrid zinnia)
This summer, just relax and enjoy your annuals: most of them don’t need deadheading!