Published in The African Violet Magazine, Nov-Dec, 2009
Ronn Nadeau, Nadeau African Violet Seeds
African violet (AV) seeds were sown on ten different commercially available germination mixes (GMs) to determine which of them were more effective for percent germination and time to onset of germination. Two of the GMs, Fafard Seed Starter Potting Mix and Premier Pro-Mix Ultimate Seeding Mix, were much more effective than the others. Five were poor for germinating AV seeds and three were intermediate. The GMs that gave highest percent germination also germinated seeds more quickly.
History and Objectives
We first reported on AV seed germination in this Magazine more than thirty years ago (Nadeau, AVM, 1978 and 1982), and we discussed the effects of light intensity on germination in the Sept-Oct, 2009 issue of AVM. In this article we present results from experiments aimed at finding the best GM on which to sow AV seeds. All of our experiments with AV seeds are aimed at finding conditions that maximize the success rate for AV growers when they attempt to grow violets from seeds.
The seeds used in this study were taken from the “Trailer batch 7” seeds at our company, Nadeau African Violet Seeds. This batch was prepared by combining seeds from twenty-five sub-batches that came from crossing trailer parent plants. See the Results and Discussion section for more about the origin and nature of these seeds.
The ten tested GMs, except for the Fafard Horticultural Vermiculite and the Mosser Lee No-Damp-Off Milled Sphagnum Moss, contained limestone for pH adjustment and a wetting agent, according to their bag labels. The main ingredients were:
(1) Fafard Horticultural Vermiculite.
(2) Fafard Seed Starter Potting Mix: 50-60% Sphagnum Peat Moss (SPM), 40-50% horticultural vermiculite (HV).
(3) Fafard Super Fine Germinating Mix: 55% Canadian SPM, plus HV and horticultural perlite (HP).
(4) Ferry-Morse Organic Seed Starting Mix: 78-82% SPM, 18-22% HP.
(5) Jiffy Organic Seed Starting Mix: 50% SPM, 50% HV.
(6) Miracle-Gro Seed Starting Potting Mix: 90-95% SPM, 5-10% HP.
(7) Mosser Lee No-Damp-Off Milled Sphagnum Moss.
(8) Premier Pro-Mix Potting and Seeding Mix: 75-85% Canadian SPM, 15-25% HP.
(9) Premier Pro-Mix Ultimate Seeding Mix: 65-75% Canadian SPM, 25-35% HP, plus endomycorrhizien innoculant (Mycorize).
(10) Sun Gro Redi-earth Plug & Seeding Mix: 55-65% Canadian SPM, 35-45% HV.
In the first column of Table 1 the GMs listed 2nd, 4th, 5th, and 6th were purchased at Home Depot or Lowes, and the others at Hummert International, a horticultural supply store in Earth City, MO (www.hummert.com). The pots and fluorescent lighting equipment are described in our article in the Sept-Oct, 2009 AVM. Lights were operated on a cycle of 14 hours on, 10 hours off.
Each part of the experiment was replicated (–A and –B pots). Each GM was combined with tap water in a 3:1 ratio (GM:water, volume:volume). No further water was applied for the duration of the experiment. Moistened GM was put in 3 ½ inch pots to within ½ inch of the top of the pot. The surface of the GM in each pot was lightly tamped down with a spoon to smoothen the surface onto which the seeds would be sown. The “Trailer batch 7” seeds (100 for each pot) were counted out ahead of time and placed in small packets. After all the pots were properly labeled (GM, date, -A or -B) and ready for sowing, the 100-seed samples were sprinkled onto the GM surfaces and the pots were enclosed in plastic sandwich bags with the flaps folded under the pots. The pots were placed directly beneath a 4- foot fluorescent light fixture such that the tops of the pots were 10 inches from the fluorescent tubes, which provided a light intensity of 11.0 EV, as measured with an incident light meter. See our Sept-Oct, 2009 article about measuring light intensities and EV values. To determine percent germination, counting of germinated seedlings began on the 14th day after sowing and was repeated on the 16th, 18th, and 24th day after sowing.
Results and Discussion
The “Trailer batch 7” seeds used in this study was prepared from twenty-five sub-batches of trailer seeds, including some that were seven years old and stored under refrigeration in sealed glass vials. This age, and the fact that we have seldom seen even fresh AV seeds germinate at a rate approaching 70%, makes it unsurprising that the best germination rate we have found in any test of “Trailer batch 7” seeds is approximately 50%. We could have usedseeds that were much fresher, but used “Trailer batch 7” because that is a large batch and one from which we are
selling our Trailer Selection seeds. For our seed sales, the number of seeds/packet takes into account the batch’s %- germination rate. Thus, if the test germination rate is 50% and we advertise 50 seeds/packet, the packets will actually contain at least 100 seeds. In Table 1, the “Corrected %-germ’n at 24th Day” column shows what we think the
germination rate on the corresponding GM would be if 100% of the seeds were viable.
Table 1 shows percent germination values and time to onset of germination data. The “Average of replicates” column shows percent germination numbers at 24 days after sowing. The data indicate that Fafard Seed Starter was the most effective GM for germination, with an average of 43% at 24 days after sowing, and Premier Pro-Mix Ultimate Seeding Mix, with an average of 39% germination, was close behind. Ferry-Morse Organic Seed Starting Mix was good for early germination but not as good as the two above mentioned GMs for percent germination by the 24th day.
Percent germination numbers for the other GMs tested were significantly lower, ranging from 11-32%. Mosser Lee No-Damp-Off Milled Sphagnum Moss (11%) and Fafard Horticultural Vermiculite (19%) had the lowest germination values by the end of the test and the seedlings were small and stunted.
The ten GMs in this study had mostly fine particles (Photo 1). Of the ten, eight were soilless mixes containing sphagnum peat moss (SPM) plus horticultural vermiculite (HV) and/or horticultural perlite (HP), in varying proportions as detailed in the Materials section. All eight of the soilless mixes also contained a wetting agent, but the wetting agents were not identified on the bag labels. Also, each of the soilless mixes was adjusted to pH 6 by addition of limestone, and we confirmed that they all did have pH’s close to 6.0. Even though the soilless mix GMs had similar gross compositions and looked similar, they varied significantly in their effectiveness as media on which to germinate AV seeds. For example, two of them gave rates of 43 and 39% while five gave rates of 24% or lower.
We do not know why the GMs vary so much in their power to germinate AVs seeds. Might it be that the wetting agents added to the mixes at time of manufacture are somewhat toxic to germination? Or do some of the GMs contain added fertilizers that are not specified on their labels? In our 1982 AVM article we reported that when “Nadeau Mix”, a mix we sold for growing AV plants, was moistened with water containing Rapid-Gro at concentrations of 0, ¼, 1, and 3 teaspoons per gallon, germination proceeded satisfactorily at each concentration except 3 teaspoons per gallon, which completely shut off germination. We hope to solve the GM puzzle with further experiments.
Finally, we would like to add an observation that is off the main subject, but might help AV seed growers. During the germination period and during several weeks after germination, it is best to maintain temperatures no higher than 85 degrees F because tiny AV seedlings do not grow well at those higher temperatures. After this time, or when the seedling leaves reach about ¼ inch in diameter, higher temperatures are okay and permit good growth.
We welcome comments, suggestions and questions about our seeds and experiments. Just e-mail us at AVSEEDS@YAHOO.COM. Happy growing!
1. Nadeau, Ronn. “Growing African Violets From Seed.”
African Violet Magazine January 1978: 7.
2. Nadeau, Ronn. “Shedding Light on the Secrets of Saintpaulia Seed Germination.”
African Violet Magazine March 1982: 36.
3. Nadeau, Ronn. “Effects of Varying Light Intensities on Germination of African Violet Seeds.”
African Violet Magazine Sept – October 2009: 10.