2025 Seedlings
DarcyD For the seedlings (last year and this year) I used Miracle Grow seedling mix that I add 25% added perlite. I think I may need to add more like 40% added perlite, if I keep using it. I purchased some Pro mix #4 but it's too late to use for the seedling starts. I really think I messed up by having too many seedlings for the warmth I could provide. My new LED lights don't give off the heat, like the grow lights I used last year. I still have the grow lights, but not enough for all the Dahlias. Growing pains, and learning lessons.
SteveM Sorry to hear about your tomato seedlings. I think anyone that grows plants is in a constant cycle of making mistakes and learning from those mistakes, or learning from success. One of the purposes of the post I made, pointing out some of the issues I've encountered growing the Dahlia seedlings, is to emphasize that it's not all easy growing.
SteveM I'm sorry 
I'd offer to send you some tomato seeds but I suspect you have some already!
It has been 35 days since I started one particular tray of my dahlia seeds. I started them all in soil this year and I move them to individual cells once they germinate. Anyway, I haven't had a single Skipley Reboot seed germinate. Until today when 3 of them came up this morning. Nature is wild!
MissyWeitzel I feel like Iād have given up by now, Iām so glad you held on! 
MissyWeitzel It has been 35 days since I started one particular tray of my dahlia seeds. I started them all in soil this year and I move them to individual cells once they germinate. Anyway, I haven't had a single Skipley Reboot seed germinate. Until today when 3 of them came up this morning. Nature is wild!
That is incredible, and so important to know. Using a "paper plate" method, I give up after around 14 days when there's been no germination for a few days.
Playing with Gemini AI, I created this chart showing quantity of my seed germination over time. The seeds were "planted" on February 24.
MissyWeitzel wow! Now if they had been in paper towels they would have rot before sprouting. At least for me. We have awful mold issues here. I prefer the soil method by far. But, I do still do those I only have a few of in paper towels.
DarcyD I learned from Ted to mix hydrogen peroxide with the water used with seeds. I believe he said 25% hydrogen peroxide and 75% water but I'm lazy and I have a spray bottle with the HP and a spray bottle of water and I just spray more of the latter. 
I had terrible mold issues last year and since implementing this I haven't seen any at all!
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I am now skeptical about hydrogen peroxide as something that kills mold. It does supposedly help seeds sprout as it gives oxygen to the embryo. The chlorine soak of the seeds and double rinse with water may work on the mold.
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Teddahlia a few days ago I went down a "rabbit hole" into an internet search on "seed disinfecting" with hot water and with bleach. There's some universities that have hot water tested on many vegetable crops, even going so far as to test if virus has been eliminated(think tomato viruses). Anybody interested can do a search. So far, the only way to figure out what works for dahlias is to do testing, and that is not an easy thing to do. I was interested in killing virus as well as fungus by the heat treatment. As with most of my internet researches, I get distracted and it's something I should do on a "rainy day", as there is too much to do in Spring. If I get around to ordering from GEOSEED, I will get a large number of dahlia seeds and do some experimenting to see if Dahlias seed survives some of the recommended temp treatments for vegetable seeds.
Tab was still open in my browser for hot water treatment: https://www.umass.edu/agriculture-food-environment/vegetable/fact-sheets/hot-water-seed-treatment
Bessie Re metal pans: I grew hydroponic tulips this winter for something to keep me entertained during the gloomy PNW winter. I made my own makeshift pin trays and had a few bulbs that I couldnāt squeeze into the trays that were plasticā¦.soooo I used some disposable metal pie tins I had found. I had an EC meter to check the EC of the hydro tulips and keep it in the ideal range adding calcium nitrate to water and basing EC off of this product dissolved into the water. This was to prevent stem toppleā¦..well day by day some trays could have a fluctuation of EC say from 1.5 one day to 1.6 or 1.7 the next day. This could happen if they were on the top rack of the shelf in the garage (warmer/more evaporation= increasing concentration and increasing EC) or if there was just a small amount of liquid in the trays when they were rooting the EC could change more because less liquid = bigger changes from evaporation or heat. However the bulbs I had in the metal pie pan went from an EC of 1.6 to 2.1 in a day!! My husband said something is probably leeching out of that pan to make it jump up that high. Glad I was checking the EC and caught it early on. Initially I was checking the temp/ph/ and EC but later only focused on EC because I saw the ph and EC were connected so if one was in ideal-ish range so was the other. Well with the EC of 1.6 the ph of the water was around 6.9-7.1 when the EC went to 2.1 the ph dropped to 4.8!! Wayyyy out of ideal range. I have since avoided metal takeout containers or pie tins for any garden projects that require ābabyingā (starting seeds, forcing bulbs, rooting cuttings, etc).
Justafewdahlias I've had a lot of chemistry courses(I think one class short of a minor), so I suspected the Aluminum pans, but unfortunately not so much as to stop using them! I bought some nice 10"x14" plastic containers at the dollar store for making bulk cuttings, so tomorrow I'll move as many of the dahlia seedlings as possible into those plastic containers. Thank you for the detailed account of your growing in aluminum pans!
Bessie Yes Iām pretty sure they were aluminum pie pans. Might have been a reaction between the liquid and the pan that caused the leeching and all of that. Maybe it doesnāt happen to soil in the same way but I just remembered this being a surprising finding for me! I find myself using milk jugs cut in half as makeshift free pots a lot this yearā¦.not the best for tiny starts but so far it has been good for potting up tubers to start early or when your doing a few cuttings of the same variety
I do soil blocking. The ideal tray for that is old cafeteria trays but I have only so many of them an inevitable run out needing to use something else. I can get aluminum trays ( same as the pie plate made from) for cheap at a local store. So far I have not noticed a difference in seedling quality in fact the ones in those trays are usually nicer because of the light reflecting off those trays. Iām not saying it couldnāt cause problems but so far it hasnāt for me and some of those trays have been reused serveral times by now.
MissyWeitzel This is what I do too. I fill a 1020 tray with soil, spread the seeds, top with soil, water in and cover with a humidity dome under lights. It works great! Before planting, I soak the seeds in a 10% bleach solution, and then rinse several times to help keep things clean. I have tried the paper towel method, but this way is a bit more forgiving if I forget to check on them : )
MissyWeitzel I tried that this year. I did the sameā¦used a bottle with a splash added. Maybe I need more. Thanks 
Sprouting seeds. Here is HH Cotton Candy as a "baby" way back when. We have not sold it much in recent years but occasionally, we will have extra tubers.