A few of thoughts here. First, we have proof of Viking settlements, but they just seemed to die off completely. It may be that before they really got settled,

A few of thoughts here. First, we have proof of Viking settlements, but they just seemed to die off completely. It may be that before they really got settled, they were just killed by natives. We don't have actual proof, it seems, of anyone else being here earlier. Outside of that, the tomato, potato, and a lot of other things, aren't native to Canada, or even the US. It's native to Central and South America, which is 4000 or so km in a direct line, and 7000 or 8000km "hugging the coast" travel from where a viking settlement was found on the coast of Canada. So just being in the "new world", won't even remotely put you in contact with everything. On the farming side, no one really understood much about soil management, conditions, crop rotation, fertilizing, drainage, fungus, "growing zones" etc, etc until the 20th century. Often, attempts to transplant crops would fail miserably, by: * placing them in the wrong location (some plants die with too much sun, others with too little) * same as above, but "requires a more southern climate" or "northern climate". Some plants literally cannot grow with short/long day cycles like the far North or South has. * placing a plant in too wet, or too dry soil for its growth requirements. One plant may rot in a certain type of soil (clay/wet/whatever), another thrive Well, there are many points like this. Farmers often knew their specific plants, but it was all guesswork compared to scientifically derived knowledge in the early 20th. So even if a handful of seeds somehow made it back to Europe earlier than Spain getting to the new world and back, there's no promise it would thrive on a first-try. Especially if it was just fishermen, not even interacting with the natives (maybe, earlier contact as you suggest). But beyond all that, superstition! When the tomato was first introduced, it was actually seen as a 'sign of the devil'. It was considered evil, and dangerous to eat. And if you look at corn, for a long time the Brits and much of Europe considered it only suitable as 'pig food'. Most humans wouldn't touch it, and likely this had also to do with taste, for the rural town I grew up had 'cow corn', which is corn hardier, quicker to grow, but not as succulent, or even very tasty (too starchy). Early farmed corn was like this, starchy, and it took centuries to get the human palatable breeds we have now. Natives in the new world used it just for flour, basically, not as a grain to eat on its own. And to speak to that, natives had to process corn in a special way: https://www.spiceography.com/corn-flour/ https://www.spiceography.com/corn-flour/ Otherwise, it severely lacked in nutrition. Yet, Europeans may have just thought it was "tradition" to prepare corn this way... I guess what I'm saying with all of this is, there's a lot of nuance here. Just taking a few seeds won't guarantee growth, or adoption. Erm, another thought: https://storytellergarden.co.uk/vegetables/when-potatoes-were-illegal/ https://storytellergarden.co.uk/vegetables/when-potatoes-wer... Potatoes were seen as deadly in some places and illegal, were seen as horrible in other places (and, people had to trick the commoners into eating them: https://www.thevintagenews.com/2018/07/28/prussian-and-the-potato/ https://www.thevintagenews.com/2018/07/28/prussian-and-the-p... )