My habit always was to take a seed potato and cut it into as many sections as it had eyes, then plant the chunks.
This usually meant each potato would get cut into four or five pieces.
Last year, I said to heck with that, and just cut them in half. To my surprise, they did much better than in the past, and I figured it out.
The plant itself “lives” off of the energy stored in the potato. So before it gets good stems and roots and leaves going, it needs that chunk of potato.
So the ones that I just cut in half got going, grew faster, and got bigger, and produced more potatoes themselves because it had a good energy store to get it going strong and vigorous.
So turn the dirt over good 16-24 inches deep, plant them with a bit of compost or manure if you have it, water them very heavy right after you put them in, and let them grow.
Forty days is kind of short but don’t deceive yourself, I’ve had potato plants sprout (and start to make potatoes) during warm spells in November!
That makes sense. I’m glad you told me - I would’ve been cheap and tried to make as many potato plants from one potato that I could!
40 days is probably a short estimate. I got it from a gardening book about this area. We certainly have from mid-June to August - that’s at least 75 days of growing weather. And it doesn’t always get cold in September right away either. Potatoes might be perfect for up there because it stays pretty cool, especially at night. Can potatoes handle a large temperature variation from day to night?