Hanging baskets have become a mainstay item for many color programs. Baskets provide the consumer with low-maintenance, long-term enjoyment. As the vegetative annual market has grown, so have the number of genera and varieties suitable for hanging basket production. Often, plants that are too large for small container production look great as a basket item when they are allowed to grow to their full potential. For 2009, Pacific Plug & Liner grew a comparative trial with an emphasis on two crops ideally suited to hanging baskets: scaevola and lobelia. The trial proved to be very showy with more than 75 cultivars compared in a mass of blue, white and purple.
When judging the results of our trial, we were particularly interested in a certain criteria in each genus. For lobelia: earliness to flower, uniformity within a series, good branching and spherical habit. For scaevola: strong natural branching, compactness and floriferous nature.
One of the first challenges when categorizing the lobelias into color groups was sorting through the extensive range of blues. The color blue is synonymous with lobelia, and the selections vary from palest blue to deepest indigo and everything in between, including bicolor. Range of habits varied slightly, but all plants were trailing, though some were heavily trailing and others slightly mounding. The compact selections definitely make tidier baskets that are ideal for transport, but the larger and more trailing selections had the most visual impact.
All of the cultivars were grown under glass at our location in Watsonville, Calif. Night temperatures were set at 53° F. There was no pinching done on the crop, but all of the varieties received three applications of growth regulators: 1-ppm Bonzi (paclobutrazol) drench at the liner stage; 1.5-ppm Bonzi drench and a 500-ppm spray of Florel (ethephon) when baskets were pot full.
Early on, we could tell that the breeding in lobelia is very good. The Hot series from Westhoff has always had impressive vigor, earliness to flower and great range of colors. ‘Hot Water Blue’ proved to be one of the best varieties, with light-blue flowers, a spherical habit and earliness to flower. The Techno series from Syngenta Flowers also showed well; in particular, ‘Techno Blue’ had one of the best habits and vivid dark-blue flowers. Syngenta has managed to develop a series of Technos to compete with Westhoff’s Hot series: the Techno Heat line. Lobelias that are more heat tolerant generally have more pubescent foliage. Selecta First Class had a range of good breeding with the Magadi series, with a number of compact selections ideal for smaller baskets and high-density production. The compact selections are also ideal for smaller container production. ‘Magadi Blue with Eye’ proved to be a top-notch cultivar.
On the larger side was the Annabel series from Danziger. Many of the Annabels were heavily trailing but made very nice large baskets, and they are ideal for mixed baskets when paired with other aggressive genera. ‘Annabel Blue Romance’ proved to be one of the favorite selections with vivid blue and white bicolor flowers. ‘Annabel Blue’ was one of the earliest and showiest solid-blue selections. Uniformity within a series was one criteria that was not evident in most of the series we trialed. But Proven Winners’ Laguna series showed to be the most uniform, with nicely matched habits among Dark Blue, Sky Blue, Heavenly Lilac and White varieties. Lagunas were not the earliest or showiest series, but the uniformity was clear. The Waterfalls from Ball were also a relatively uniform series, but somewhat different in habit from most of the other series: They had smaller flowers and a compact, almost succulent growth.
The number of blue selections was numerous; however, when selecting purple and white varieties the options are significantly less. ‘Hot Lavender Blue’ proved to be the most dark and vivid purple selection available. Overall, it’s hard to go wrong with most of the varieties we compared, and the number of selections continually grows. Consider using compact selections for smaller pot production and look for the Hot or Heat selections for better summer performance. Westhoff’s lobelia ‘Superstar’, though not in our trial, was introduced for 2009, a unique variety with a very upright habit and dark indigo blooms with a large white eye — an exciting new introduction.
Scaevola are great heat-loving annuals from Australia. Commonly known as fan flower, it has been bred for great performance in baskets. Scaevolas naturally flower in late spring and respond well to warm temperatures and longer days. The main growing issues with scaevola are branching and habit. Our trial proved to be a little too early to see them at their peak flowering potential, but we were able to get a good idea of habit and flower size and color range.
The scaevolas were grown in the same glass house as the lobelia; 53° F nights provided good growth, but warmer night temperatures may have helped move the trial along quicker. We gave them no pinch and applied the same growth regulators as the lobelia: 1-ppm Bonzi drench at the liner stage; 1.5-ppm Bonzi drench and a 500-ppm spray of Florel when baskets were pot full.
Habit and branching were the main attributes to compare with scaevola; early on, it was evident that the Suntory Surdivas were significantly more compact than any other series we trialed. The Surdivas made a very compact basket and are ideal for smaller container production like quarts and gallons. Beyond the Surdivas, we did not see significant advantages or disadvantages among the other series. The number of purple varieties from even one breeder seemed excessive without any distinct differences. Westhoff had some great selections, including one notable bicolor called ‘Diamond’. The Bombays from Syngenta Flowers proved to be very floriferous and slightly more upright in growth. ‘Bombay Pink’ and Westhoff’s ‘Topaz Pink’ were the only two pink selections, both nice but with no significant differences. Danziger had a number of purple selections; ‘Blue Haze’ proved to be one of the darkest.
Although the breeding on both these genera have produced some very nice varieties, baskets are only one area where they can be utilized. Some recent breeding is focused on compact upright habits suitable for small container production. More color development is definitely another direction for breeding these genera; additional whites and darker pinks with improved habits would help complete the range within a series. In the short term, lobelia and scaevola will continue to be great low-maintenance plants for summer baskets and mixed containers.