daikon to hourensou ha reizouko ni aru node, suupaa ni ikanakute sumimasita.

は marks 大根とほうれん草 as the topic of the first clause.

So the sentence is structured like:

• 大根とほうれん草は = as for the daikon and spinach
• 冷蔵庫にあるので = since they are in the refrigerator
• スーパーに行かなくて済みました = I didn’t have to go to the supermarket

A learner might expect が instead of は, and が is also possible in some contexts. But は sounds natural here because the sentence is setting up those vegetables as the thing being talked about.

Very roughly:

• 大根とほうれん草は… = speaking of the daikon and spinach...
• 大根とほうれん草が… = the daikon and spinach are the ones that...

In this sentence, は feels more neutral and topic-based.

と means and when connecting nouns.

So:

• 大根とほうれん草 = daikon and spinach

This is a complete, definite list of the items being mentioned.

If the speaker wanted to mean something more like things like daikon and spinach, they might use や instead:

• 大根やほうれん草 = daikon, spinach, and so on

But here the sentence is specifically talking about those two items, so と is the natural choice.

Because に is used to mark the location of existence with verbs like ある and いる.

• 冷蔵庫にある = to exist/be in the refrigerator

With existence verbs:

• に = where something is
• ある = exists/is (for inanimate things)

By contrast, で usually marks the place where an action happens:

• 冷蔵庫で食べる = eat at/by the refrigerator
• スーパーで買う = buy at the supermarket

So:

• 冷蔵庫にある is correct because this is about where the vegetables exist.

Japanese normally uses:

• ある for inanimate things
• いる for animate beings like people and animals

Since 大根 and ほうれん草 are vegetables, they take ある:

• 大根がある = there is daikon
• 猫がいる = there is a cat

Even though vegetables are living things biologically, in Japanese grammar they are treated as inanimate in this kind of sentence.

ので means because / since, and it gives the reason for what follows.

Here:

• 大根とほうれん草は冷蔵庫にあるので = since there was daikon and spinach in the refrigerator...
• スーパーに行かなくて済みました = ...I didn’t have to go to the supermarket

So ので connects the reason and the result.

Compared with から, ので often sounds:

• a little softer
• a little more explanatory
• a little less blunt

So this sentence feels like a calm explanation: Since I had those vegetables in the fridge, I didn’t need to go to the supermarket.

Both can mean because, but the nuance is a little different.

• ので = more explanatory, softer, often more objective-sounding
• から = more direct, sometimes more personal or assertive

Compare:

• 大根とほうれん草は冷蔵庫にあるので、スーパーに行かなくて済みました。
• 大根とほうれん草は冷蔵庫にあるから、スーパーに行かなくて済みました。

Both are grammatical. The version with ので sounds slightly smoother and more matter-of-fact.

A rough feeling is:

• ので: Since that was the situation...
• から: Because of that...

This is a very common and useful pattern:

• verb-negative て-form + 済む
• meaning: to get by without doing X / to not have to do X

So here:

• 行く = to go
• 行かない = not go
• 行かなくて = without going
• 行かなくて済みました = it was settled without going / I didn’t have to go

This pattern often expresses relief or convenience: something was unnecessary.

More examples:

• お金を払わなくて済んだ。 = I didn’t have to pay.
• 電話しなくて済みました。 = I didn’t have to call.

So the sentence is not just a plain negative. It has the nuance of avoiding the need to go.

Both ～ないで済む and ～なくて済む are used, and in many cases they mean almost the same thing:

• スーパーに行かないで済みました
• スーパーに行かなくて済みました

Both mean I didn’t have to go to the supermarket.

In everyday Japanese, ～なくて済む is extremely common. It often feels like the standard set phrase.

Very roughly:

• ～ないで can emphasize without doing
• ～なくて済む is a fixed expression meaning manage without / avoid having to

For learners, it is safe to understand this sentence as a standard example of the ～なくて済む pattern.

Because the main event being reported is in the past: I ended up not needing to go.

• 済みました is the main verb of the sentence
• so its tense determines the overall time reference

The first clause, 冷蔵庫にあるので, gives the reason. In Japanese, the plain non-past form in a subordinate clause can describe a state that was true at the relevant time.

So this does not necessarily mean the vegetables are in the fridge right now at this exact moment. It means that, at the time in question, they were there, and because of that, the supermarket trip was unnecessary.

In more explicitly past-focused Japanese, you might also hear:

• 冷蔵庫にあったので、スーパーに行かなくて済みました。

That version makes the pastness of the first clause more explicit.

Yes, absolutely.

• 冷蔵庫にあるので = since they are/were in the refrigerator
• 冷蔵庫にあったので = since they were in the refrigerator

Both can work, depending on context.

The version with あるので can sound like the speaker is describing the situation more generally or vividly, as the basis for the decision.

The version with あったので makes the first clause clearly past.

So:

• あるので = natural and common
• あったので = also natural, especially if the speaker is looking back on a completed situation

Japanese often leaves out subjects when they are obvious from context.

In English, you need to say I didn’t have to go. In Japanese, the I is usually omitted if the listener can easily understand it.

So the sentence naturally implies something like:

• I didn’t have to go to the supermarket
• or possibly we didn’t have to go, depending on context

This omission is very normal in Japanese and happens constantly.

Yes, へ could also be used.

Both are possible:

• スーパーに行く
• スーパーへ行く

In this kind of sentence, both mean go to the supermarket.

The general difference is:

• に marks the destination more directly
• へ emphasizes the direction toward that destination a little more

In everyday speech, に行く is extremely common, so スーパーに行かなくて済みました sounds very natural.

Yes. The pattern ～なくて済みました often suggests:

• relief
• convenience
• avoidance of effort

So the sentence does not just say I didn’t go to the supermarket. It says more like:

• I didn’t need to go
• I was able to avoid going
• Luckily, going wasn’t necessary

That nuance comes from 済みました, which has the sense that things were resolved or managed without doing that action.

So the overall feel is something like: because the needed ingredients were already in the fridge, the supermarket trip could be skipped.