Earliest Potatoes available in the US?

I'm having some trouble trying to find very early seed potatoes. Several seem to be available in the UK, but in the US... I'm not having any luck.

I want something that will produce a crop in under 60 days in PNW Late Spring Early Summer conditions. [Long Sunlight Hours, a little rain early in the growth but not much towards the end, moderate heat with daytime highs likely averaging 70-75 and night-time lows in the mid to high 50's.]

I'm basically planning gardens for the north side of structures, and I need something that can crop in the months on either end of the Summer Solstice [Mid-May to Mid-July] and I need enough of these to be able to either pull off a disease-preventing-polyculture or a fairly diverse crop rotation.

I have little experience with potatoe,s mainly experimenting with redskin potatoes.

Here is a list of early varieties. Good luck!

Irish Cobbler- 65 days to maturity - http://www.ufseeds.com/Irish-Cobbler-Seed-Potatoes.item

King Harry- 70-90 days - https://www.woodprairie.com/product/414/certified-organic-seed-potatoes

Caribe- purple skinned- less than 90 days. https://www.woodprairie.com/product/caribe-seed-potatoes/certified-organic-seed-potatoes

Ugh, the closest in your list is the Irish Cobbler.

Maybe I can hack it by planting it early and trying to time the vine emergence with the start of the period of light I'm working with...

Getting the soil to warm up somehow seems like a valuable thing, as would be sprouting the seed potatoes before you plant. Here's a vendor with a group of "early" potatoes. I bet if you call them and explain your project, they will have some suggestions. Probably worth trialing several to see what performs well in your soil and also stores adequately for your needs. July is pretty early unless you a planning a lot of summer potato salads.

Ann Torrence wrote:July is pretty early unless you a planning a lot of summer potato salads.

60 days between mid-May and mid-July. These are the months where the sun is close enough to vertical that the north side of a structure [with a path along the wall] is able to produce quick crops. I've pulled it off with radishes before and now I'm looking to expand my operations.

For various reasons, mainly frost, your not going to find something earlier in the States.
Just look for early potatoes, and plant the seed potatoes a couple weeks before your last frost average.
When it comes time for -when- you want to harvest your potatoes, if the vines haven't died back on their own, then you break or cut off the vines, and 2 weeks later once the skins have set(for storage reasons), harvest/dig up your potatoes.
This, of course, will effect how big your potatoes are, but you can do that with just about any potato.
In Newfoundland, we plant about Mid May, and harvest as early as Late July, digging up test plants to see how big the potatoes are. My family once planted store bought Yukon's in Mid-may, and the vines had died off in August, we were sure the sun had killed them, but when we dug them up, the smallest potatoes were the size of a mug, and the biggest ones were the size of dinner plates.

I recommend going with Yukon Gold, a yellow at 65days, or any potato rated for Zone 3/4, which will always do better in a warmer zone.
The size and quality of your potatoes all depends on the quality of your soil for the most part, and the frost date. As long as they get 5ish hours of sun a day, they'll still grow. The size might not be worth it, but they'll grow.

http://www.groworganic.com/non-gmo-and-organic-seeds/vegetable-seeds/seed-potatoes/spring-potatoes.html
Sells some early potatoes, but they won't ship till April for frost & storing reasons unless your on the west-coast.

http://www.burpee.com/vegetables/potatoes/
Has a red potato rated for 60 days, and a fascinating 'masqurade' that's 63 and blotted yellow & purple skin.

https://www.mainepotatolady.com/productcart/pc/viewCategories.asp?idCategory=3
Has a number of Early Potatoes

http://www.potatogarden.com/

Tho there may be shipping restrictions based on the season, or agricultural issues for both sites, depending on your state.