Dahlia Talk
04-22-25
by Ted J. Kennedy
33 people from three countries sat in front of their computers or cell phones or tablets and talked about only one subject for over two hours. This discussion session is evolving. Formalities like introductions or where are you from or how many dahlias do you grow and so forth are declining. We may not know the person in the little window on the screen all that well but we do know that person shares our affection for dahlias.
Two subjects were scheduled for discussion and both were discussed:
Can pollen convey virus to the seedlings(by the bees was in the question but by any means is more correct) ? What an esoteric question. It had been researched before the meeting by one member and he stated that said that pollen can convey virus to a seedling. I could end this discussion now but which of the 6 or 7 viruses and what was the demonstrated infection rate? Do the seedling plants show symptoms or only test positive for the virus? My take away is that it is a good idea to use healthy plants for breeding. Having said that, several years ago one of the most experienced dahlia breeders used a known virus infected plant to breed several very successful show dahlias. He said he needed those traits from the sick plant and no other flower had them. Obviously, not all the seedlings were infected.
The other topic was again on fertilizer(the most discussed subject concerning dahlias for some reason) and the question was does too much fertilizer negatively impact dahlia tubers? I am sure this relates to the scientific study on fertilizer rates for growing dahlias done in Utah. The study said that higher rates of nitrogen caused the plants to grow more tubers(actually as measured by weight and not by tuber count). General knowledge has been that nitrogen fertilizer should not be used after August(late August for me) as it affects the storage of the tubers. The study did not address this issue and it was proposed that nitrogen may prevent the formation of carbohydrates(starch) in the tubers. Another person thought it had to do with the plants continuing to grow rapidly and that immature tubers will be included in the tuber harvest. These immature tubers have thin white skins and not store well. No consensus was reached except that if you want your tubers to store better, cut back on nitrogen after August. Show growers may ignore this as they want nice flowers, not nice tubers.
Barbed dahlias were discussed. One somewhat experienced person said, âWhat are barbs?â I will not bore you with the answer(you should be attending the Dahlia Talk sessions). Jean Heeringa was one of the foremost breeders of barbed dahlias but is no longer breeding. She used the âVistaâ prefix on her flowers. Her niece(no name or location) has several of her varieties. One of the people said she is starting a breeding project to create more varieties. Magic Moment has some barbs and it was positively mentioned as an âoldie but goodieâ .
We discussed skinny necks. No, not people's skinny necks but dahlia tuber skinny necks. They break and the tuber is no longer viable. It is a genetic trait and several famous dahlias were mentioned: Red Velvet, Jessica and the fat tubers of Hamari Accord with the tiny skinny necks. One possible cultural solution is to grow the tuber in a gallon sized pot that has the bottom removed. The tubers are forced to grow downwards and have less tendency to break their necks when harvested. The person who asked the question will do a scientific study and report to us next year with a ten page dissertation on the subject and will use only very long scientific words in the report.
The subject of dahlia cuttings was discussed for quite a long time. Subjects: Rooting mediums, humidity, length of cuttings use of domes, use of fertilizer in the water, use of rooting hormones(some brands), time from cutting to having roots and amounts of lighting, necessary temperature, possible diseases, and some things I have forgotten. One thing I did not forget was that I admitted to the group that one of my âwhiteâ cuttings(taken from a tuber still in storage) had not rooted in over 3 weeks while all the others had rooted. When I was removing the cutting from the medium after the 3 weeks, I noticed the cutting was placed into the medium âupside downâ with the leaves below the soil and the root end above the soil. The leaves were still white and the portion above the soil quite dry. I was expecting some sympathy from my fellow growers but there were several people who laughed instead.
We discussed dahlia planting dates and our Australia member quickly said âOctoberâ and we laughed again. It turns out that in the Vancouver, Canada planting dates are getting later, not earlier. This is due to the change in Spring weather from warm and dry to about the same warmth but too wet to plant. It is that way to a degree here in Portland too. Lots more discussion on when to plant.
We discussed growing dahlias in pots and not little pots but big pots. Long discussion and we decided that growing in pots(or grow bags) can work very well. Fertilizer and watering were discussed. Growing in warm weather areas was discussed. Too much detail for this summary.
Giant dahlias generally always get discussed as some show growers love them. The show varieties of Aggie White and Louis White were discussed in the context that neither make many tubers and one is even worse(sorry, I cannot remember which). However there was a revelation that even though there are no tubers, the âclumpâ can be potted up in the Spring and some cuttings can be taken and that was âhot newsâ to a couple of people. Growing Ivory Places in Australia was discussed. If people ask what was discussed on âDahlia Talkâ, tell them this sentence: How they grow Ivory Palaces in Australia. You will verify that they all a bunch of fanatics.
Steve Cox told a humorous story on fighting spider mites with a special concoction sold to marijuana growers that requires a hazardous waste uniform for application. You should been there for this one.
We talked quite a bit about British dahlias. Too much detail for this summary.
James Kassner is chairman for the National Show in Chicago. He did such a moving presentation on why we need to attend that show that it should have been recorded and put onto You tube. Can you imagine going to a dahlia show that is located in a botanical garden that covers 385 acres of plants?
By the way, many people on Dahlia Talk say nothing at all and just take it all in.
Supposedly, Dahlia Talk is scheduled for two hours. It actually starts 15 minutes early and continues for another half an hour afterwards. And 25 of the 33 people were still on the Zoom meeting at the end of that half hour.
Again, I left out most of the discussion and there were many other things discussed. Next session is May 27 at 7PM.
