Mimulus from Seed to Seed in Sixty Days

Table of Contents and IntroductionAfrican Violets: the Doyen of House PlantsAgapanthusAlstroemeriasAmerican SagebrushesAmerican WildflowersAndean Nymph - a pink mimulusAquilegias (Columbines)AuriculasAustralian AnnualsBellis Perennis (Daisies)Black-Eyed SusanBlue African LiliesBreeding DelphiniumsBreeding Fuchsias: Part 1: From SeedBreeding Fuchsias: Part 2: HybridisationBromeliads from SeedButterflies in Soy SauceCacti RaisingCampanulasChilean Bell FlowerChilly Treatment for Peruvian LiliesCollecting SeedConserving Annuals and BiennialsCosmosCucumbersCycads: Living FossilsCyclamen for IndoorsDahlias from SeedDamping OffErythroniumsF1 Hybrid - What Is it?F2 and Open Pollinated VarietiesFrom Obscurity to the Height of FashionGentiansGeraniumsGermination to Pricking OutGolden Impatiens - The StoryGrowing Alpines From Seed: Part 1Growing Alpines From Seed: Part 2Growing Bananas From SeedGrowing Cyclamen From SeedGrowing Eucalyptus From SeedGrowing Ferns from SporesGrowing Foxgloves From SeedGrowing Fritillarias From SeedGrowing From Seed: From Packet to SoilGrowing Hardy Ferns from SporesGrowing Hardy Geraniums From SeedGrowing Lewisias From SeedGrowing Magnolias From SeedGrowing Meconopsis From SeedGrowing Proteas and Related Genera from SeedHandling Small SeedsHardy Annuals: Part 1Hardy Annuals: Part 2Hardy CyclamenHardy SpurgesHelleboresIncreasing your Violas and ViolettasKeeping Records of Seed SowingLettuce - the Vital Part of any SaladLord Anson's PeaMagnolias - the Root of the ProblemMimulus from Seed to Seed in Sixty DaysNew Guinea ImpatiensOld-fashioned Sweet PeasOnions with EverythingPansies are not Difficult to Grow from SeedParsleyPerennials for American GardensPetuniasPhygelius - their cultivation and propagationPinks: Evocation of the PastPlants That Flower OncePrickly but NicePropagatorsRadishesRaising PalmsRaising PrimulasSalad Leaves - a lot to be desiredShow Stoppers Twice OverSowing SeedsSowing in Open GroundSowing to Feed our FriendsSturt's Desert PeaSweet Peas - Autumn SownSweet Peas - Sowing and GerminatingTall and HandsomeTechniques with Tiny SeedTexas BluebellThe Effect of Light on Germination and SeedlingsThe Nervous PeaThe Scarlet Welsh PoppyThe Search for the Yellow Sweet PeaToad LiliesTomatoesTreasure Hunt for TasteUnderstanding Latin NamesUnique Poppy (Mother of Pearl)Viability of VegetablesWeaning SeedlingsWill the Real Mimosa Please Stand Up

Jim Borland discusses the acceleration of a plant's life cycle, particularly with regard to mimulus.

The ability to accelerate plant growth to what appears to be ridiculous extremes is probably only appreciated by two groups of people: those who wish to travel for extended periods in interplanetary space and those whose careers depend upon the yearly introduction of new hybrids to the buying public.

While the former group has only relatively recently evolved as a viable and necessary adjunct to human space travel, the latter group has been practicing their particular kind of voodoo for decades.

Even in the late '70s the subject of accelerated growth was given short shrift in college level horticultural courses. But even then it was known that through the utilisation of supplemental light, constant fertilisation, temperature manipulation and raising ambient levels of carbon dioxide to 3 and 4 times their normal, the growth of nearly all plant species could be greatly accelerated. Increased yields of this acceleration were often measured in plant size, number of blooms produced per square foot, or shortened periods to attain blooming or a particular plant size, and a host of other measurements dependent solely upon the species and intended purpose.

Shortly after beginning my association with the late Charlie Weddle, who with two other horticultural futurists began the Pan American Seed Company (A seed company for Professional Growers), I learned that the advanced techniques only briefly mentioned in college actually had been practiced by them for 20 or more years.

Charlie, who is credited with the development of the first hybrid Petunia cultivars (e.g. 'Comanche') along with a fistful of other internationally prominent hybrid Snapdragon (e.g. 'Rocket'), Ageratum and Zinnia (e.g. 'Peter Pan') cultivars, matter-of-factly utilised germination chambers, supplemental light and carbon dioxide enrichment techniques in their development.

The process, as Charlie, late in his seventies, continued it with Petunia development, utilised a germination chamber consisting of shelves, each lighted overhead with a bank of 40watt cool-white or warm-white fluorescent tubes arranged in a side-by-side fashion so that little space existed between individual tubes. Electrically, all the ballasts needed for the operation of these tubes were removed to the outside of the shelf where they could dissipate their operating heat without creating an oven-like condition between the shelves. Although fluorescent lamps are known for their evolution of little heat when compared to incandescent lamps, it is of sufficient quantity when enclosed by shelves to create a deliciously warm environment for the germination of seeds.

The shelves, of simple design and construction, were arranged so that when a filled wooden seed tray was placed upon them, only a few inches remained between the top of the seed tray and the surface of the fluorescent tubes. Each shelf was covered with plastic to prevent extraneous water from interfering with the operation of the tubes. Seed trays were removed for watering.

Petunia seed was usually surface sown into clean soil, watered gently with a fine spray and covered with a disinfected sheet of clear plastic before placing the seed tray into the lighted shelf arrangement. With a bit of practice and experience with soils, initial watering and the use of plastic, nothing else was needed until the seed germinated. This usually took place in a few days during which time the lamps remained lighted 24 hours a day. After germination, the plastic covering was removed but the seed trays remained on the shelves for a week or more during which time they grew rapidly to the transplant stage.

After transplanting to some form of small cell-type container, the transplants were moved to a full-sunlight bench for continued growth in a greenhouse whose atmosphere was enriched with carbon dioxide. This was accomplished by a very special natural gas burner which was regulated so that the normal ambient 330 ppm carbon dioxide found in the atmosphere was raised to between 1000 and 1500 ppm.

Earlier research indicated that not only did elevated levels of carbon dioxide accelerate plant growth, but that this practice was especially beneficial in winter when either manual or automatic greenhouse venting systems were often not put to use for days on end. In such a situation the natural levels of carbon dioxide which we are taught exists in the outside atmosphere actually are quite reduced in a closed environment, especially in one where a large mass of living plants are actively removing it for food production. Measurable decreases in plant growth are noted for such confined environments during a time of year when most greenhouses must be at full production to supply holiday plants or blossoms.

Through this process Charlie was able to hybridise a generation of Petunias in approximately 60 days and turn around 5 or 6 generations a year, while the ordinary gardener might only produce one.

Recalling this experience and making slight variations at the Denver Botanic Gardens, I found that many other species respond similarly.

One which responded remarkably well was Mimulus guttatus, a common but floriferous species of the Rocky Mountain region which has yet to be incorporated, to my knowledge, into any commercial improvement programme.

Interest in this particular genus was actually the result of the convergence of several serendipitous events. One was the discovery, by a small group of dedicated botanic garden volunteers, of M. gemmiparus in a rather unique and unreported location in Rocky Mountain National Park.

This peculiar species is known to propagate itself only vegetatively through specialised leaf axil buds, known as gemmules, since studies have proven its pollen to be sterile. These gemmules eventually fall from the plant and occasionally are carried to their resting place by water. The species is undoubtedly related to other local Mimulus, perhaps even M. guttatus, but the evolutionary development of its unique form of self perpetuation remains a total mystery.

It was discovered growing on a recently formed, small rocky alluvial plain at an elevation several thousand feet lower than previously known,- and, because this new location was caused by a flood, it indicated the potential of yet another unknown population at a higher elevation, should it have survived the flood.

This discovery was coupled with a rare plant programme at the Gardens which involved the fiery red M. eastwoodiae and my own personal discovery of the remarkable attributes of M. cardinalis, since witnessed cascading from vertical walls deep within the confines of the Grand Canyon. The recent installation of high pressure sodium lights in several greenhouses resulted in initial studies of Mimulus in general, with M. guttatus acting as the work-horse.

It was soon discovered that these and other Mimulus species germinate in only a day or two when surface sown and kept under conditions of continuous light and warmth at 20C (70F).

Pots containing germinated seeds were immediately placed 3 to 4 feet below high pressure sodium lamps which emitted, when measured by a simple photographer's light meter, between 400 and 600 foot candles of light. Since these particular lamps were of a bulky yet extremely light efficient design and the bench over which they were suspended was in a poorly lighted area, the shadow that they cast during daylight hours was sufficient to force their operation 24 hours a day, even during the summer season.

The growth produced by these conditions was such that it was a distinct pleasure to rush to the bench each morning to witness the changes in size and shape of each plant wrought in the few hours between termination of yesterday's work and the beginning of today's. Time to first transplant and final transplant into a 4 or 6 inch-pot took place with such rapidity that only the swift pace between blooming and seed harvesting upstaged it.

The soils used for this study consisted of sphagnum peat moss: perlite (2:1 by volume), which was amended with sufficient lime to bring the pH of the mixture to between 6.3 and 6.5. Growth was additionally accelerated through the use of fertilised irrigation water which was used continuously from the time of germination to the termination of the study. Although the sources of these fertilisers varied from one study to the next, the basic chemical fertiliser used was a complete one which, when mixed with water, provided at least 150 parts per million of nitrogen with each watering. Since the species is a moist soil inhabitant, soils in the pots were kept continuously moist to mimic this condition.

At least part of this study was to produce a homozygous population of M. guttatus through a series of self-pollinations and to determine how many times this could be done without loosing vigour in the parent plants.

Through this portion of the study it was found that each blossom was easily emasculated, even when one waited until the blossom actually opened, thus making both self and cross pollination operations easy and uncomplicated.

It was also found that the potential for each blossom pollinating itself was high, due to the location of the stamens which are attached to the corolla tube. The eventual demise of each blossom begins with the collapse of the corolla tube which causes the anthers, complete with their expelled but remaining pollen grains, to pass over the still receptive stigma as the corolla disarticulates from the calyx, thus affecting self-pollination.

With no wind or pollinating insects in the greenhouse, the initial stages of cultivar development became a simple matter of only having to collect ripe capsules with the full knowledge that each had not become contaminated with pollen from another plant.

Experience quickly indicated that capsules were ripe for harvest when the slightest hint of brown colouration was shown. Waiting too long to harvest usually resulted in the expulsion of the powdery fine seed onto the soil surface, where in a few days a green mat of newly germinated seedlings completely covering the surface was to be seen.

Even without the use of carbon dioxide during these studies, the elapsed time between sowing and harvesting seed took no more than 60 days. I strongly suspect that paying even closer attention to air temperatures, fertiliser levels coupled with the introduction of high levels of carbon dioxide to the growing area, this time could be reduced to between 30 and 45 days without too much trouble and that other species of Mimulus would react similarly.

Although none of this equipment or special procedures are necessary to successfully germinate and grow a wide range of beautiful Mimulus species, nearly everyone has access to simple fluorescent tubes and even high or low pressure sodium lamps, as well as excellent soils and the ability to precisely measure the fertiliser levels of irrigation water. With these, even the home gardener can explore the yet untapped colourful resources of the genus Mimulus.