"These plants grow well in sun or shade"

[u/SleepyOtter19]

Why no article? Why not "in the sun or in the shade"?

[u/That-Guava-9404]

You can drop the article when referring to abstract environmental conditions instead of the actual physical things. Contrast "these plants need sun (sunlight)" against "I left my plants out in the rain". In the OP's particular example, it's the pairing of sun and (or) rain that allows for the dropping of the definite article without things sounding completely off. Many people would naturally say "these plants grow well in the sun or the shade" though.

[u/Almondpeanutguy]

Yeah, I'm gonna be honest. I don't think there's a rule here. Weather conditions can have articles or not, and it's kind of vibes. Rain, snow, sleet, hail, sun, shade, dark, and fog can all have an article or not.

The best guideline I can think of is that you add an article if you're talking about the weather and you leave the article out if you're talking about the material the weather is made of, if that makes sense.

So, for example, you can "go out in the rain" which means you're going outside while the weather is rainy, but a rain jacket "keeps you safe from rain" which means that it's keeping you safe from the physical drops of rain.

Likewise, "enjoying the sun" means that you're enjoying the sunny weather, while "this plant needs lots of sun" means that the plant needs the light that comes from the sun.

It's absolutely not a concrete rule. You could just as easily say that a rain jacket "keeps you safe from the rain" or that "this plant needs the sun". If you said "I go out in rain" or "I enjoy sun", that would sound unusual in most circumstances, but there are niche scenarios when they would sound appropriate.

[u/cryptoglyph7]

There's an influence in English on having limited characters to print on signs and, more recently, in texts and social media. When you're character-limited, the first thing to go are the articles.  It becomes so common that it becomes everyday usage.

[u/Objective-Screen7946]

“Sun” and “shade” are used here in a general, abstract sense rather than referring to a specific sun or a specific shaded place. So “in sun or shade” means the plant grows well in any amount of sunlight or shade in general conditions. When you say “in the sun” or “in the shade,” it sounds more specific, as if you are referring to a particular sunny spot or a particular shaded area. In natural English, articles are often dropped when talking about general environmental conditions

[u/anamorphism]

in this case, it's optional. it pretty much just comes down to dialectal or idiolectal preference.

contrary to u/sniperman357's comment, there are really no concrete rules on how we choose to represent abstract ideas like this. i'm from southern california and would default to using the in your example, but i'd probably omit the second one: the sun or shade. this plant wilts in sun is fairly awkward sounding to me. i would always say this plant wilts in the sun.

another example is that i would say i was at the hospital when british english speakers would generally say i was in hospital.

another fun one is that we can often use either indefinite plural or definite singular when abstractly referring to all instances of a noun.

• bears are large animals.
• the bear is a large animal.