A decade ago, Diascia wasn't offered very often, if ever, in the mega-garden centers I tend to frequent, and so I just thought longingly about my sweet Diascia in the intervening years. Every time I purchased seeds, I put "d-i-a-s-c-i-a" into the search engines, but came up with nothing. Eventually, one of my favorite gardening websites, High Country Gardens, started selling "perennial, cutting-propagated cold-hardy Diascias." Hmmm. I tried them, once in a container (they weren't that cold-hardy) and once in the ground. I think my cold, wet winters just don't agree with them.
When our editor suggested an article on Diascia varieties, I jumped on the idea! The idea of researching other Diascias (besides the High Country Garden ones) was intriguing, because I didn't know there were any. Now I know that while I was looking for Diascia seeds, breeders in England, Holland, Australia and Israel had been busy cloning Diascias in all sorts of colors and with all sorts of habits.
Diascias in the wild: Diascias, I learned, come from South Africa, in the Drakenberg Mountains. They are in the Scrophulariaceae family, along with Nemesia and Alonsoa. There are over 70 separate species recorded (and they're still counting). Diascia means, in Greek, DI=two and ASKOS=bladder or sac. Many people will tell you that this refers to the two snapdragon-like spurs which protrude and is a translation of its common name, "twinspur," but the other version is far more interesting!
Sex for a Diascia: reproduction for a flowering plant normally occurs when the male pollen is transported to the female ovaries, via wind, bee, butterfly or whatever. For the 70 different species of Diascia growing wild in South Africa, each has two little oil sacs located deep in the corolla. These sacs are located SO deeply that ordinary bees cannot pollinate them; thus exported Diascias do not set seed. There is one genus of bee, from South Africa, of course, the Rediva genus, with forelegs long enough to reach far enough down into the flower to harvest the oil and fertilize the Diascias. Eight Rediva species have been found with long enough legs to pollinate Diascias. More amazingly, in different areas the corollas are of different lengths: here 3mm longer, there 4mm shorter. Each population of Diascias has a corresponding bee population with the right length forelegs.
Incidentally, once Diascias do produce seed, they stop flowering. So perhaps it's just as well for those of us who like the flowers to last (and last) that our local bees aren't up to the job.
Hybridizing: the very first Diascia hybridizer seems to have been British John Kelly in 1971, who crossed two Diascias and named the best-looking seedling D. 'Ruby Field' after a woman with whom he worked. Naturally, when the bee connection was finally discovered in the 1980s, plant breeders realized that they would have to hand-pollinate the Diascia if they wanted to experiment with hybrids. The first person known to do so on a big scale was Hector Harrison, from Appleby, in England, in 1985. Many of his hybrids are still in common use, such as 'Appleby Apricot,' 'Hannah Rose,' 'Red Ace,' 'Ice Pole' and 'Salmon Surprise,' and are, some think, sturdier than their new-fangled cousins.
Most old-type Diascias have a lax habit, are no more than 6 to 15 inches tall and are perfect trailing or spilling out of a container. But they were all pink or rose. Then Harrison started hybridizing, and close on his heels followed other breeders in England, Holland, Australia and Israel. It turned out that diascias were perennials, in these mild climates, and would thrive and propagate well there, unlike in Massachusetts, for instance, where they are definitely an annual!
Modern Hybrids: Graham Noel Brown in Cobbity, Australia introduced the Sun Chimes series back in 2004. (See Sun Chimes Red to the right.)
Flying in from Holland in 2007 came the Flying Colors series, hybridized by Klemm. The Flying Colors series includes Trailing Antique Rose, Trailing Red, Apricot, Appleblossom and Coral. Trailing Antique Rose and Trailing Red, uh, trail, but the others are more upright. From Holland we also have the Picadilly series, which were hybridized by Stemkens in 2007, and include lilac and blue (D. 'Denim Blue', shown in the very first picture), which I can't wait to see in person! The "red" is usually a dark reddish rose, or a dark rosy red, but we don't mind.
The Danzinger Company, in Israel, has come up with 16 new varieties of Diascias in the 'Genta' line using tissue culture. Most have larger flowers, stiffer stems and are more upright than the species. Sygenta Flowers is wholesaling 'Genta Light Pink'TM and 'Genta Red'TM to markets in Europe, Africa and the Middle East. I guess it depends on where you are when you find your Diascia. (I was unable to reach anyone to give me permission to reproduce any photos of 'Genta,' and they're not on the market yet, so there are no images in PlantFiles. Sorry.)
2011-12 Ball Horticultural Company this year is wholesaling five varieties of D. 'Picadilly' (originally from Stemkens), six of D. 'Romeo' (which is trailing) and five of D. 'Juliet' (an upright variety), and four of D. 'Diamonte' (seed-grown!), for a grand total of 20 diascia cultivars. In the fairly recent past, Ball has also marketed D. 'Whisper' series and the D. 'Wink' series. You can get D. 'Diamonte' at Pase Seeds or Park Seed.
And last but not least, Proven Winners marketed ten Diascia varieties in 2011: three from the 'Flying Colors Series' and eight others, including 'Flirtation Orange,' which is the one I am growing this year, and which seems to be very popular. These are available mail-order for customers in the U.S. There are even Diascia cultivars I couldn't trace.
There is a lot of discussion among breeders, growers, sellers and patent offices as to what constitutes a truly new and different Diascia. Is it better to have a flat, visible flower, or a more trailing habit? (Personally, I'm a sucker for a trailing or climbing plant every time.) How important is it that the plant be self-branching, or not require dead-heading?Is one good coral cultivar enough, or do we need five perfect coral cultivars, some light coral, some deep coral, some trailing, some upright, some apricot, some peach, and some salmon and apricot?
Ball Horticultural Co. 'Picadilly Coral'
Ball Horticultural Co. 'Picadilly Salmon'
How many oranges? Some which won't give up in the heat, like zinnias, and some which will act more like pansies, ceasing to bloom in the hottest part of the summer but reviving with the pleasant coolness of fall? Do we need some with miniature flowers and some with larger flowers?
These two don't both look orange to me: Proven Winner's 'Flirtation Orange' on the left looks more coral, and Ball's 'Wink Orange' on the right is a really orangey orange.'Flirtation Orange' by DaylilySLP
'Wink' Orange by Kell
Q: Are these pinkish purples, or purplish pinks? And are they different, or is it the light, or time of day?
A: Whatever you call them, they are different. One is D. 'Romeo Bright Pink' on the left; to the right is 'Picadilly Pink' — four years older.
While I am perfectly happy with corals and oranges, I understand that many people prefer these bluer tones. So I concede, their development is a good thing.
D. 'Romeo Bright Pink'
D. 'Picadilly Pink'
Diascias always seem to look stunning in hanging containers, whether or not they are designated as "trailing" varieties. To the left, an unknown pink trailing Diascia, and to the right, courtesy of Ball Horticultural Co., 'Romeo White' ('Balwinwite' PP17,176), a brand-new trailing Diascia, image property of Ball Hort. Co.
Anonymous pink trailing Diascia Barbera D. 'Romeo White'
On the left, D. 'Apricot Queen' at Van Dusen Botanical Park in Vancouver, Canada. I wonder, is it perennial there?
On the right, D. 'Diamonte', which has only just become avaiilable—to home growers and nurseries—a seed-grown form of Diascia. DG subscriber TomTom has grown D. 'Diamonte' in what she describes as tiny containers.'Apricot Queen' at Van Dusen Public Garden in Vancouver, Canada, photo by growin.
'Diamonte Pink' started from seed in "little tiny containers" by TomTom.
The most important issue is whether you can figure out which cultivar of Diascia you have and what it likes. In the middle of writing this article, I'm realizing that my D. Flirtation Orange probably wants more fertiilizer and more sun, and that it is NOT a trailing cultivar so I'll be waiting a long time if I expect it to trail! In general, and I wish to emphasize this is a generalization, Diascias like sun and rich soil, i.e. liquid fertilizer or compost. Some like consistent moisture and some can tolerate drier conditions. If your Diascia seems to be overwhelmed by the sun, cut it back by a third and see if it produces new growth in a few weeks. If not, let it rest in a shadier spot until it revives.
Diascia should be considered as a tender perennial in the U.S. west, southwest and south. If you want to be sure of continuing a particular plant, in case your area should freeze, advises Christine Boulby, former Head of the National Diascia Collection in England, take a soft stem cutting in the summer while growth is active. Diascia does very well in containers, although I have seen plenty of photos os the taller species planted in the ground and looking splendid. I have seen reports of Diascia in North America, Israel, Australia, Japan and Europe. However there are many other Mediterranean-type climates where it ought to also flourish.
Diascia is a lovely little flower. (In fact, I saw hanging pots of orange Diascia with pink petunias outside Dunkin Donuts today. Pink and orange, are of course, the theme color of the Dunkin Donuts brand.) Diascia shine in combination plantings and do beautifully solo in containers as well. Try some Diascia this fall or next spring or both!
Although I tried, my photo of 'Flirtation Orange' was nothing compared to the one that DG member DaylilySLP had taken. To DaylilySLP, Evert, kell, growin and TomTom, I am in awe and gratitude for permitting me to use their photographs in this article. I also deeply appreciate the permission of Ball Horticultural Company to use their copyrighted images in this article. Please respect that copyright and do not reproduce without their express permission.
Email correspondence with Christine Boulby, who is the former Head of the National Diascia Collection, England.
Email correspondence with Ginny Kovach, of Ball Horticultural Company.