hareta hi ha, syokubutu wo soto ni dasimasu.

晴れた is the past short form of 晴れる, but in Japanese it is also commonly used before a noun to describe a completed or established state, like a sunny day or a day that has turned out sunny.

So:

• 晴れた日 = a sunny day
• 晴れる日 would sound more like a day that will be sunny or a day on which it becomes sunny

In this sentence, 晴れた日 is the natural way to say on sunny days.

The は marks 晴れた日 as the topic.

So 晴れた日は means something like:

• as for sunny days...
• on sunny days...

This pattern is very common when talking about what happens under certain conditions:

• 暑い日は、... = On hot days, ...
• 暇なときは、... = When I have free time, ...

Here, 晴れた日は sets the situation: when it’s a sunny day.

Here, 日 means day, not sun.

That is because it is part of 晴れた日, which means a sunny day. In this expression, 日 is read as ひ.

So:

• 日（ひ） = day in this sentence
• not sunlight or the sun itself

Japanese often uses 日 in time-related expressions like this.

The particle を marks the direct object of the verb.

The verb here is 出します, which means to put out, to take out, or to bring outside, depending on context.

So:

• 植物を出します = (someone) puts/takes the plants out

The thing being moved is 植物, so it takes を.

外に means to outside or more naturally outside as the destination.

The particle に is used because 出します involves movement toward a destination.

• 外に出します = take/put (something) outside

Why not the others?

• に marks the destination or resulting location
• へ also marks direction, but 外へ出します would focus a bit more on direction than destination
• で marks the place where an action happens, so it would not fit here

So 外に is the most natural choice for putting something outside.

Here, 出します means to take out or to put outside.

The basic verb is 出す, which has several related meanings, including:

• to take out
• to put out
• to bring out
• to send out

In this sentence, because of 外に, it clearly means to move something to the outside.

So 植物を外に出します means:

• I put the plants outside
• (someone) takes the plants outside

The exact English wording depends on context.

出します is the polite non-past form of 出す.

Japanese often uses the ます form in neutral polite statements, especially in textbook sentences and everyday polite speech.

The non-past form can mean:

• a habitual action
• a general rule
• a future action, depending on context

In this sentence, it sounds habitual:

• On sunny days, (I/we) put the plants outside.

So the ます form here is polite and natural.

Japanese often leaves out the subject when it is understood from context.

So this sentence does not explicitly say who puts the plants outside. It could mean:

• I put the plants outside on sunny days
• We put the plants outside on sunny days
• They put the plants outside on sunny days

In natural Japanese, this omission is very common. If the speaker and situation make the subject obvious, Japanese usually does not state it.

植物 literally means plants, and it is grammatically fine here.

However, in everyday conversation, native speakers might often use a more specific word if they know what kind of plants they mean, such as:

• 花 = flowers
• 鉢植え = potted plants
• 観葉植物 = houseplants / foliage plants

So 植物を外に出します is correct, but depending on context, a more specific noun might sound more natural in real life.

The comma helps separate the topic phrase from the main statement.

So the sentence is divided like this:

• 晴れた日は、 = On sunny days,
• 植物を外に出します。 = (I) put the plants outside.

Japanese commas are often used more flexibly than English commas. This comma is not absolutely required, but it makes the sentence easier to read.

Yes. Even though it literally means sunny days, in natural English it is often best understood as:

• when it’s sunny
• on sunny days

Japanese often uses a noun phrase like 晴れた日 where English might prefer a clause. So the structure is different, but the meaning is the same.