haru ni naru to, haha ha syokutaku no ue ni hana wo kazarimasu.

春になると means when it becomes spring or more naturally when spring comes.

This is made from:

• 春 = spring
• に なる = to become
• と = when / whenever

So the pattern N になると means when it becomes N.

In this sentence, 春になると、母は… gives the setting: Whenever spring comes, my mother...

The に is part of the expression 春になる, meaning to become spring.

With なる, the thing you become is often marked with に:

• 先生になる = become a teacher
• 元気になる = become well / energetic
• 春になる = become spring / it becomes spring

So this に is not a time marker here. It belongs to なる.

No. Here と is not the and particle.

In this sentence, と is a conditional/temporal marker meaning when or whenever.

So:

• 春になると、母は花を飾ります。 = When spring comes, my mother decorates with flowers.

This と is often used for things that happen naturally, regularly, or as a general tendency.

Examples:

• 春になると、暖かくなります。 = When spring comes, it gets warm.
• ボタンを押すと、ドアが開きます。 = When you press the button, the door opens.

They are similar, but not the same.

• 春に = in spring
• 春になると = when spring comes

So:

• 春に花を飾ります。 = She decorates with flowers in spring.
• 春になると花を飾ります。 = When spring comes, she decorates with flowers.

春に simply gives the time. 春になると emphasizes the change of season and the idea that this happens as spring arrives.

は marks 母 as the topic of the sentence.

• 母は = as for my mother / my mother

The sentence is talking about what the mother does when spring comes.

So the structure is:

• 春になると = when spring comes
• 母は = as for my mother
• 食卓の上に花を飾ります = she puts/decorates flowers on the dining table

Using は makes the mother the main topic of the statement.

Because 花 is the direct object of the verb 飾る.

• 花を飾る = to decorate with flowers / to display flowers

The mother is the person doing the action, and the flowers are what she displays, so を is correct.

• 母は花を飾ります。 = My mother decorates/displays flowers.

If you used 花が, it would sound like the flowers are doing something, which does not fit here.

飾ります is the polite non-past form of 飾る.

It can mean:

• to decorate
• to adorn
• to display

In this sentence, it most naturally means something like:

• puts flowers out
• displays flowers
• decorates the table with flowers

So this is not necessarily flashy decoration. It can simply mean placing flowers nicely as decoration.

食卓 means dining table or the table where meals are eaten.

It is a more specific word than テーブル, which just means table.

• 食卓 focuses on the dining table, often with a slightly home/family feeling.
• テーブル is a general loanword and can refer to many kinds of tables.

So 食卓の上 means on top of the dining table.

Because 食卓の上に specifically means on top of the dining table.

Breakdown:

• 食卓 = dining table
• の = of
• 上 = top / above / surface
• に = location/destination for placement

So:

• 食卓に could sometimes be interpreted more loosely as at the dining table
• 食卓の上に clearly means on the surface of the dining table

Since flowers are being placed/displayed somewhere, の上に makes the location precise.

Because に marks the place where something is put or exists in this context.

With verbs of placement, に is very common:

• 机の上に本を置きます。 = Put a book on the desk.
• 壁に絵を飾ります。 = Hang/display a picture on the wall.

Here:

• 食卓の上に花を飾ります = display flowers on the dining table

So に marks the location where the flowers are arranged.

Japanese non-past forms like 飾ります can refer to:

• present
• future
• habitual/repeated action

In this sentence, because of 春になると and the overall context, it sounds habitual:

• Whenever spring comes, my mother puts flowers on the dining table.

So it is not talking about one single action happening right now. It describes something she generally does each spring.

Yes, but the nuance changes.

• 母は = makes mother the topic; this sounds natural for a general statement about her habit
• 母が = puts more focus on mother as the one who does it

Compare:

• 春になると、母は食卓の上に花を飾ります。 = When spring comes, my mother puts flowers on the dining table.

  • neutral, topic-based, natural for describing a habit

• 春になると、母が食卓の上に花を飾ります。 = When spring comes, my mother is the one who puts flowers on the dining table.

  • more contrastive or focus-heavy

In most ordinary contexts, は is the more natural choice here.

The comma simply helps separate the opening time clause from the main sentence:

• 春になると、 = when spring comes,
• 母は食卓の上に花を飾ります。 = my mother displays flowers on the dining table.

Japanese commas are often used more flexibly than English commas, but here it makes the sentence easier to read. It is very natural to include it after a longer introductory phrase like 春になると.