True but let's not put all the blame on the potato. During the Famine years Ireland was a net exporter of food...

And the irish reliance on potato was directly caused by the english Penal Laws under which until the late 18th century catholics were forbidden many thing[0], including getting an education, purchasing land, long land leases (more than 31 years), primogeniture (catholic land had to be equally divided between all sons unless the eldest converted to protestantism, which would quickly lead to fragmentation and plots too small to feed their owner… which could then only be bought by protestant absentee landlords since other catholics were barred from buying them, you can see its success in irish catholic holdings falling from 25% of Ireland in 1688 to 5% in 1776).

The Penal Laws were indeed

> a machine of wise and elaborate contrivance, as well fitted for the oppression, impoverishment and degradation of a people, and the debasement in them of human nature itself, as ever proceeded from the perverted ingenuity of man.

[0] you can hear the evil cackling in the background as you go down the list: https://en.wikipedia.org/wiki/Penal_Laws_(Ireland)#Ascendanc...

But was it food that could have fed the population or luxury food (spices, cacao or something like coffee beans) ?

No it was your typical farm food (cattle, grain etc.). Most of these shipments were under armed guard by British soldiers. There was no shortage of food. Whilst the famine itself was devastating, the results were politically motivated and driven.

Grains and other edible crops (peas, onions), livestock, processed meat and produce (between January 1847 and September 1847, Ireland exported more than 7 million pounds of butter).

It was food that could have fed the population. In particular corn/wheat/other grains.

Are you familiar with (a) the climate of Ireland in the 19th century and (b) the growing conditions demanded by (most) spices, cacao, and coffee beans?

Yes, I am.

Then why would you have wondered if Ireland could have grown those things.

I did not. These were just typical examples to illustrate what I had in mind when asking about any homegrown Irish luxury food (I don't know if Ireland has any). Hence the « or something like coffee beans ».

Whereas some things are fairly straightforward to grow from their own last-crop seeds, resowing potatoes from some you already have often results in disease.

I grow a lot of different things in my backyard. From one lettuce, coriander, radish, pumpkin or tomato plant, I can collect loads and loads of seeds to regrow. In the case of a lettuce plant, it's thousands of seeds.

Potatoes are trivial to grow from old shrivelled supermarket stock (and sometimes scraps with the eyes intact) but 80+% of crops I've grown this way have been riddled internally with disease.

Pictures here: https://www.google.com.au/search?q=potato+disease&source=lnm...

Seed potatoes are so inexpensive, it's not worth using old potatoes (though I have done that many times).

I don't know where you live, but around here supermarkets will soon be selling 5lb bags of seed potatoes at comically low prices. It is ridiculously cheap to grow some staples: I can buy 100 onion sets for $2.00/bag at my local "pricy" feed store. Enough corn to plant an acre costs about $5, etc...