I will post my short article for the Portland Dahlia Society Bulletin here first.
Dahlia talk 062723
This session was not as well attended as usual with only one person from Australia and about 20 people checked in to talk. A new member named Sam Moses participated from Eastern Tennessee and gave us a lead on buying T-tape at a very low price from a chain of Amish stores in Tennessee. I did not write down the details. He has been growing dahlias for many years and like many people who participate, does not have a local club. We did a short discussion on T-Tape and suffice to say most of us use it to water our dahlias. Do not forget to buy a pressure reducer.
The subjects were getting rather advanced and obscure and I will share the some of the things that were new to me. We had a discussion on pot tubers that started with the basic question of can you plant a pot tuber into the garden after you take the numerous cuttings. The yes, answer was prefaced by you must give the pot tuber some fertilizer and time to get back some of the vigor it lost providing the cuttings. The conversation went on to discuss what size pots the growers use, what size flats, whether above the ground or in the ground. One person said he planted his pot tubers into 3.5 inch pots(smaller than most of our 4 inch pots) and placed his pots into standard 10 x 20 nursery trays. It was pointed out that the cheap trays are no good and heavy duty trays were best and one brand was Anderson flats. He places his flats of pot tubers into/onto the ground partially buried. He also pointed out he sometimes keeps over pot tubers in storage for an extra year as they store so well. Several of us gasped for air(well I gasped) as this was not something we had heard of before. The price of 4 inch pots was discussed and I said the OBC store in Canby was selling Gage(good brand) 4 inch pots for 1,000 for about $150.00(later I found out it is 1,500 pots not 1,000 and they are sold out). 4 inch pots fit 16 per flat when you use 16x 16 flats. Pot tubers are an interesting subject and there are lots of good questions about them.
Can the old dog learn a new trick? We talked about the various techniques of topping, disbranching, disbudding, disbudding more than one down and lots of methods concerning the management of the growth of our dahlias. We talked about growing poms and using manicure scissors to remove the involucres at the rear of the blossom. We talked about the UK growing methods for poms. And finally we talked about the most important, most interesting subject that borders on divulging state secrets: How do you grow Giant dahlias? I must say that I had never heard of the secret methods employed by the top UK and Australian growers to get the very best and biggest giant blooms. The question of how do you grow the best giant dahlias started off with the typical answers. The most common answer is to limit the plant to two blooms by disbranching. I pointed out that Steve Santos who has won as many giant show awards as anybody and he just plants more plants of his giants and for example grew 30 plants of Inland Dynasty the year I talked to him. The small gardener may trouble doing that. And now for the big reveal.
In the UK there is a show grower named Dave Gillam. He has had considerable success in showing giant dahlias in the shows. I had never heard of his “secret” method of getting the very best plants. As with nearly everybody in the UK, he grows his dahlias from cuttings taken from pot tubers. He roots them and transfers them to 4 inch pots and grows the plants to 12 or more inches in height in his greenhouse. At planting time he removes the plant from the pot and buries the root ball. We all do that. He then cuts off the stem of the plant so that there will be new shots coming from an inter node that is either just above the soil level or just below it. Did I just say he grows a 12 inch plant and cuts off most of it when he plants it? Yes, this is how he does it. He believes that the plant will now have extra roots as there is the original root ball from the 4 inch pot and two more root balls that will form from the shoots that emerge from the inter node. Three sets of roots give you a very vigorous plant. There you go. You now know how to grow 16 inch in diameter giant flowers with intense color. I am sorry if I divulged a state secret and will not be visiting the Tower of London in case they do not allow me to leave for several years.
Fertilizer is always discussed ad nauseam on Dahlia Talk.. No exception for this meeting. The new product of the year is Warren Vigors liquid formula. Azomite was mentioned and it drew no discussion. Bone meal was discussed in the negative. Dick Parshall is using alpaca dung. The “new “ product that can be used on dahlias is potassium sulfate. If it is added to the garden just before blooming time the flowers will be better and have more color. The a second application is done a few weeks later to enhance the size of the dahlia tubers. The advocate said that he doubled his yield of tubers. I take all such things with a grain of salt but it does sound good. Unlike phosphorus, potassium cannot easily be over applied and lots of it can help the dahlias. Potassium sulfate is the preferred version of potassium .Oops, hold the presses because there is another source of potassium that is just as good and Dick Parshall and Max Ollieu have been using it for years. It is wood ash from burning wood in your wood burning stove. It is also very alkaline and helps with the acid in PNW acid soils.
I am leaving out lots of content from the meetings in these short articles and if you are not doing Dahlia Talk you ought to start.
