Over the winter between 2020 and 2021 I conducted a winter potato experiment. I found that Yukon Gold potatoes could be grown in Zone 9b over the winter, howbeit they don’t enjoy it much. That being said they did a lot better than I would have thought. The main concern that would take place is that the health of the foliage would decline over January and February. This is likely because of the minimal amount of light at that time of year.
For anyone who resides in a moderate climate where the yearly low hovers around freezing (between 30 and 32), I decided to try growing potatoes over the winter of 2020. I'm in Northern California Bay Area 9b. I began with organically-grown disease-free potatoes. For context, I planted into 3 different plots in different locations. I mainly grew Yukon Gold. So this is what I learned:
1: Potatoes can grow over the mild winter.
2: As soon as they are damaged by a light frost, the above-ground growth will stop, but the below ground growth will continue. On a related note, once frost damage has occurred, the potato tubers do not send out additional growth.
3: Squirrels leave the potatoes alone! (=
4: If you have a sheltered area with lots of radiant heat in the evenings, you may be able to grow potatoes without any concerns. Though a few potato plants in my raised bed garden received a little damage, the majority are still growing. (The other two plots did freeze, but not a hard frost).
5: As a summer gardener, I plan to start my next potatoes in September/October instead of November/December.
I hope this helps those of you who live in areas where you would like to grow potatoes, but have summers that are too hot to grow them.