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Who Says Bigger is Better?
Experiments in Dwarfing Waterlilies

by Rich Sacher, Louisiana USA
Click images to enlarge

For many years now, growers and hobbyists in the water gardening trade have been expressing their desire for smaller waterlilies. Many tropical waterlilies have a spread of five to six feet (1.5 to 1.8 meters) and larger, and this limits the number of plants that can be grown in the average size lily pond. And there is certainly a need for dwarf lilies that would fit neatly into small water garden pots and planters. So, size matters! In this case, bigger is not better.

However, breeders of waterlilies have not yet been able to develop a series of genetically dwarf tropical lilies which grow and bloom easily, while staying small. Naturally, we would want a small plant with BIG flowers!

Among the few dwarf lilies that I have stumbled across in my seedlings, they all shared three unhappy traits: they were very slow growing, they were poor bloomers, and they were difficult to propagate. Not exactly what I had in mind. They might have become potential parents for future hybridization ... if I could have grown them long enough to work with them. Perhaps vigor and dwarfness are mutually exclusive genetic traits. So the thought occurred to me: maybe I can play a little trick on Mother Nature?

Growers of ornamental plants have been using various growth retardants for decades now, to produce plants that are more compact while retaining normal flower size. Growth retardants such as Bonzi, Cycocel, B-Nine, etc., have been used as a spray or drench on commercially produced floral crops such as mums, poinsettias, Easter lilies, bedding plants, etc. These growth regulators work by reducing the length of the stems, producing compact plants with dark green leaves.

Perhaps the most common example is the dwarfed Hibiscus, sold in six or ten inch (15 or 25 cm) pots. Note that the plants are called “dwarfed”, rather than “dwarf”, to indicate that they have been artificially reduced in size. They may retain their compact habit for an entire growing season; or, in more tropical climates, the plant may outgrow the dwarfed habit after three or four months, and resume its normal growth pattern. The effect of these growth retardants is a temporary one, not a permanent alteration.

I asked myself: what would happen to tropical waterlilies if they were treated with a commercial growth retardant? Would it reduce the size of the plants? Would it work on hardy lilies? How about night bloomers? Would it damage the foliage? Would flowering be reduced, in size or numbers? Could it be applied as a spray or drench? Which retardant would be the best one to use? At what concentration? And how often? Would it be toxic to the fish in the pond? Would it be toxic to ME? If it worked ... how long would the dwarfing effect last? And, could a protocol be established to make it feasible for commercial growers to produce these dwarfed lilies for the trade? So many questions!

I have a surplus of ‘Queen of Siam’ lilies, growing in my greenhouse ponds. Could I turn the ‘Queen of Siam’ into “Tiny Princess Thai“? Idle curiosity conspired with some free time, and invited me to do a little experimenting.

In late afternoon, I took out of the pond three ‘Queen of Siams’ which were in six inch (15 cm) pots, with lots of roots coming out of the pots, and put them into containers of plant growth retardant, at two tablespoons (30 milliliters) of plant growth regulator per gallon (3.8 liters) of water. The entire pots and crowns of the plants were covered by the solution. The containers were then lifted into large plastic bags which were tied closed for the night, and left on the greenhouse bench. This enabled the roots and crowns of the plants to be submerged in the solution overnight, while preventing their leaves from drying out.

Using the same concentration of two tablespoons (30 milliliters) per gallon (3.8 liters), I also sprayed three ‘Queen of Siams’ in an adjacent pond, covering their leaves completely with the spray solution.
In a third pond, I had more ‘Queen of Siams’ which I left untreated as a control. All these plants had been planted in the greenhouse at the same time, and the light, temperature, and fertilization was the same for all of them.

The next day, after 16 hours in the growth retardant solution, the submerged potted plants were removed from their growth retardant solution and returned to the pond. The plants whose leaves had been sprayed with retardant were left as they were. There was no sign of toxicity to any of the plants, nor to the fish in the ponds. 

After two weeks, it was obvious that the lilies that were soaked overnight were putting out leaves which were much smaller than the leaves they had at the beginning of the experiment. After four weeks, none of the original leaves remained, and all the post-drench leaves were easily one half the size of the control leaves in the adjacent pond. (See photo.) The overall spread of the three drenched plants was likewise reduced by one half. The flowers on these dwarfed lilies were the same size as flowers on untreated lilies. 


The ‘Queen of Siam’ plants that had their leaves sprayed with retardant showed only a very slight reduction in size of the new leaves, and after four weeks, even that slight reduction had disappeared. Perhaps a stronger concentration would have produced better results for the sprayed plants ... or, perhaps a second spray could have been applied, a week after the first. Or perhaps a different growth retardant would have worked better when applied as a spray. Or perhaps soaking the roots in growth retardant is the only way to go. Or, perhaps not! Who knows?

Because it was now already October, it seemed impractical to do further experiments on size reduction. The real challenge, I thought, would be to attempt to dwarf waterlilies with growth retardants in spring, and see how long the dwarfing effect lasts into the summer months. I hope to do more trials with growth retardants during the 2010 growing season, and discover if artificial dwarfing of waterlilies will be practical.

So here I am, in the middle of an unusually frigid New Orleans winter, daydreaming about some summertime possibilities. How about a beautiful Australian waterlily with big flowers, short petioles, and a spread of only a few feet? Or a gorgeous tropical night bloomer with a dainty reach of just three feet? And what about Victoria ... can she be shrunk into a Lilliputian Little Vic? Now, that would be no tiny accomplishment! As they say, “The best things come in small packages.” 

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