Is this correct?

[Darkestseasonofall]

I was reading an article on the BBC website (I appreciate they aren't the last bastion of perfect SPAG), they've written this "They can grow far more poppy - as well as other crops."

It does not read well to me, surely it should be poppies not poppy, however I then realised we grow corn and wheat, not corns and whests. Flowers are always in plural e.g roses or daffodils.

Does the plural change when the thing growing is to be used for something other than ornament? The poppies in question were destined to be used in heroin production.

Thanks in advance you clever lot.

I would say poppies too

They're wrong, it should be poppies.

Yes, it’s correct. There’s a difference between Poppy (flower), which is a countable noun, and Poppy (drug), which is uncountable. Countable means you can literally count them, like pennies or roses. Uncountable are things you can’t count, like bread or wheat, as you say. First online source I found says:
pies for 1. Plant Biology[countable] a plant having showy, usually red flowers. Drugs[uncountable] an extract from the juice of the poppy, as opium.

why can't you count bread?
What about horses and sheep? You can count sheep

You can count loaves of bread but not bread.

Curios about sheep too though. And fish.

You just say I'd like some bread, or lots of bread, you don't stick an s on the end.
If you want plural you have to say loaves of bread. The bread itself doesn't get the plural. Same as wheat or barley or rice. You'd say two pieces of rice, not two rices.

Sheep and fish are different. You can count them, but the plural happens to be the same as the singular noun.

It's correct but we're just not used to hearing it.

A poppy field.
A wheat field.
A corn field.

I'm even more confused now .
If the flowers were for decoration they'd be a field of poppies, but as they're for heroin it's a field of poppy?
Sometimes I've seen fishes written, which also confuses me.
I'm a reasonably intelligent 40 year old, and I've still not mastered the English language, it must be neigh on impossible to learn as a second language, with all its idiosyncrasies.

There are some words that can be countable and uncountable, but there’s a difference in meaning or use. Poppy is one of those. Other common ones off the top of my head -but the other way round, where we normally use the uncountable version, but there is a countable version where we can just add an s and make it countable- are fish/fishes, people/peoples, sky/skies, etc.

Fishes can be used but is more for if you are describing a few different species of fish.

Ignore my last sentence above. I’m getting muddled between different types of plurals, not countable and uncountable nouns.

It's correct.

You can count sheep
There's a difference between uncountable nouns, which have no plural, like "rice" or "wheat", and invariant nouns, whose plural is the same as the singular, like "sheep". You can say "two sheep", but not "two wheat".
In this case "poppy" is being used as a uncountable noun like "wheat", not an invariant noun like "sheep".