You can raise the temp above 212*F. I first want to say that I don't do this or condone it, pressure canning is too safe and easy to cut corners in my opinion, but if you look at the really old methods they added a lot of salt to the water in the pot.
In the same way that salt lowers the freezing temp of water it raises the boiling point. By bathing in boiling salt water and for extended periods of time they HOPED to kill off all of the nasties. I've even seen one set of instructions that was saltwater bathing in boiling/cooling cycles. That one was pretty wild, time consuming and didn't add anything helpful that I could see.
So, a saturated salt solution will get to 253*F. Interesting.... but still not to the requisite 255*.
Still, that tidbit will get tucked into my brain. Although with 3 All American cancers, extra parts (haven't needed any of them in 30 years yet!) And 3,000 regular lids plus 1000 Tattlers, and 4000 extra rubber gaskets... it won't be my problem to deal with!
It's wise to think about where the botulism spores come from, and try to be laboratory clean when canning anything low acid, especially if the approved methods aren't available. You can't get botulism if you didn't get spores in the jar!
I'd also say that canning root veggies (carrots, beets, etc) or potatoes ought to be off the list if you don't have a pressure canner... it can be difficult to clean them completely. Plus, they store well in a root cellar, or even left in the ground.
We've lived on the seasonal eating plan for decades... I don't buy fresh warm season vegetables or fruits in winter. Our first greens are winter lettuce... a loosehead lettuce which self seeds and starts to grow in early April (northern NY state) We add chickweed and purslane, as we're weeding the gardens for planting.
Strawberries are the first fresh fruit, and very welcome after the winter apples have run out.
We eat fresh out of the gardens until the first killing freeze ( we were picking fresh red raspberries until November 13th this year!) The root veggies, celery (in pots) and cabbage are used out of the root cellar, usually until March... potatoes usually keep until May, and new potatoes start coming in mid July.
During the "gap time", we eat rice, barley, pasta and the frozen potatoes ( French fries and mashed) I put up when they start showing sprouts.
Berries are frozen and turned into jam. We can applesauce, peaches, pears and cherries from the farm.
Our grown kids spend a LOT of money on fresh organic fruits and vegetables out of season... but they can afford it. I find we really appreciate the homegrown fresh stuff when we haven't had any in a few months.
Summerthyme