Q/A #31 - Moldy Seeds Won't Germinate.

February 8, 2023

Q/A #31 - Moldy Seeds Won't Germinate.

Hi, I'm trying to germinate various plants from seed. Pinguicula poldinii, Drosera filiformis, Utricularia volubilis, & Sarracenia purpurea. I believe these all need cold stratification. I left them all in my refrigerator in moist peat moss with perlite for approximately 6 weeks. Some white mold did occur but i treated with neem oil. I took them out of the refrigerator and placed them in my basement greenhouse under T8 grow lights and steady 65 to 70% humidity and 65 to 70 degree F temps. They've been in the greenhouse for approximate 6 weeks with no germination. Anything i can do differently to help germination?
(Submitted in February 2019.)

I have no experience with germinating Utricularia from seed, so I can't really give any useful advice on that one. With the other three, depending on how long the mold was growing on the seeds, it could have killed them. If you caught the mold right away, the seeds might have a chance. If the mold was on the seeds for a while, they're likely toast.

If the seeds are still viable, 6 weeks is a fairly short stratification period. We usually leave our US-native seeds outdoors, or in an unheated greenhouse for the winter. With Sarracenia they usually germinate in May. Drosera filiformis usually grows like a weed. So, these seeds may need longer stratification. I've only successfully germinated P. poldinii once, but I treated them the same as Sarracenia or US-native sundews. So, our stratification is usually a lot longer than 6 weeks.

You might also need to wait longer than 6 weeks after stratification. Some have taken up to 8 weeks. Generally, we give seeds 3 months to do something. After that, if no germination, we toss them.

Do you have any idea how fresh the seeds were? Depending on the vendor, if the seeds weren't stored properly, or was old, that could be what you're dealing with as well. I've bought lots of seeds over the years, and even with our level of experience, got few or no germinations if the seeds were old or left unrefrigerated for more than a couple of months. Unless the vendor tells you specifically when the seed was collected and how they were stored, it can be hit and miss.

The original question and response have been edited for publication.
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