Why do some plants refuse to make tubers, or good tubers?

Dahlia53

It could be variety (never had good luck with Tartan and some purples) but I think it could be something else; I just don't know what. Advice on how to promote better tuber production - and is it too late to try now? I have used fish fertilizer and some kelp meal but don't know if it's too late to give one more fertilizing and if so, what to give? Does it have to do with watering? If I end up with only the mother tuber, should I just try planting it again next year? Thanks in advance.

Teddahlia

Every trait in dahlias is genetic. Tuber making and tuber storage abilities are genetic. Tartan is so pretty that no matter how difficult it is to store someone will be able to keep some. Not me.
You have not heard of the "Curse of the Purple Dahlias?" I wrote lengthy article about that many years ago and I got the original idea from an old dahlia book from the 1930s of 1940s.
There cultural things you do that can help:
(1) Do not try to keep tubers from the purple varieties that do not store well. It can be a waste of time.
(2) I bet you want to try anyway. Dig them first before the weather turns bad. The disease is fungus related and there is more fungus and fungus spores around after the weather turns wet and cool.
(3) (4) (5) (6) all help too but I am out of time.

Dahlia53

Teddahlia Yes, Ted, I remember that article and now if I lose a purple I love, I just buy another. - thanks to that article.

Thanks for your wisdom - and you're absolutely right; why fuss with varieties that are not going to store well or make tubers if it's genetic anyway?

Haha I love your solutions! I try to dig before the big rains come. Now that I know about #1 I'll get all the fussy ones I want to keep first. Yes I may want to try to keep Lilac Time. I don't keep many purples anymore. Diva is a tried and true that always makes good tubers for me, but it's more maroony red purple. I like chimacum del blomma; that one does well for me. I love Thos. Edison, Lilac Time, and Le Baron's purples best. They have morphed over time and it's hard to find the 'blue purple' varieties of them anymore. I don't care: Lilac Time's form makes me swoon anyway 😆
Today i found a frog as small as my thumbnail nestled in its petals.

My garden landlady and I trade tubers back and forth. Right now I have Tartan - which I originally gave her - and she doesn't. Hers failed - rot. I'll be lucky if it even makes one tuber to send her way again. You're right, it is so pretty. But if I lose it again I'm not buying it. You have me thinking that I need more blue and blue violet flowers in the garden, which would solve the purple issue.