אם הייתה לי גינה גדולה, הייתי שותלת שם עץ ופרחים.

Hebrew usually does not use a basic verb like English have in sentences like this.

Instead, it uses a possession pattern:

• יש לי גינה = I have a garden
• literally: there is to me a garden

In past or hypothetical settings, יש becomes a form of היה / הייתה:

• הייתה לי גינה = I had a garden / if I had a garden

So לי means to me, and the whole structure expresses possession.

Because גינה is a feminine singular noun.

In this possession structure, the verb agrees with the thing possessed, not with the person who has it. Since גינה is feminine singular, Hebrew uses הייתה.

Compare:

• היה לי בית = I had a house
• הייתה לי גינה = I had a garden

In very casual speech, some speakers may say היה לי גינה, but standard Hebrew prefers הייתה לי גינה.

That is normal in Hebrew.

For an unreal or hypothetical condition, Hebrew often uses past-looking forms in both clauses:

• אם הייתה לי... = if I had...
• הייתי שותלת... = I would plant...

This is similar to English, which also uses a past form in If I had... even though the meaning is not really about the past.

Hebrew does not need a separate word exactly like English would here.

The idea of would plant is expressed by:

• הייתי שותלת

This is made from:

• הייתי = I was / I would be
• שותלת = planting / plant

Together, in this context, they mean I would plant.

Because the speaker is female.

The participle שותלת is feminine singular. Hebrew often marks gender in verbs and verb-like forms.

So:

• female speaker: הייתי שותלת
• male speaker: הייתי שותל

English does not show this difference, but Hebrew does.

Because adjectives must agree with the noun they describe.

Here, גדולה describes גינה, and גינה is feminine singular, so the adjective is also feminine singular:

• גינה גדולה = a big garden

Compare:

• בית גדול = a big house
• גינה גדולה = a big garden

Because Hebrew often leaves out subject pronouns when they are already clear.

In הייתי שותלת, the word הייתי already tells you the subject is I. So אני is unnecessary unless you want emphasis.

You could say:

• אני הייתי שותלת שם עץ ופרחים

but it would sound more emphatic, like I would plant...

Because these nouns are indefinite.

The sentence is talking about:

• a big garden
• a tree
• flowers

not about specific, already-known ones.

If the nouns were definite, Hebrew would use ה:

• הגינה הגדולה = the big garden
• העץ = the tree
• הפרחים = the flowers

Notice that with a definite noun + adjective, both get ה:

• הגינה הגדולה

שם means there.

It refers back to the garden: if I had a big garden, I would plant a tree and flowers there.

It helps make the location explicit, although in some contexts Hebrew could leave it out if the place is obvious.

Yes. Hebrew word order is fairly flexible.

The version you have is very natural:

• הייתי שותלת שם עץ ופרחים

But you may also hear:

• הייתי שותלת עץ ופרחים שם

The first version usually sounds smoother and more neutral.

Yes. לשתול is completely natural here.

It can be used for planting flowers, plants, and also trees. There is also the verb לנטוע, which is especially associated with planting trees.

So these are both possible, depending on style:

• הייתי שותלת שם עץ ופרחים
• הייתי נוטעת שם עץ ושותלת פרחים

The original sentence is natural and correct.

No. אם by itself is enough.

So this is perfectly normal:

• אם הייתה לי גינה גדולה, הייתי שותלת שם עץ ופרחים.

You can add אז for emphasis, especially in speech:

• אם הייתה לי גינה גדולה, אז הייתי שותלת שם עץ ופרחים.

But it is optional.

Only the second clause would change:

• אם הייתה לי גינה גדולה, הייתי שותל שם עץ ופרחים.

Why only that part?

• הייתה still agrees with גינה, which is feminine
• שותל / שותלת agrees with the speaker

So the gender of the speaker affects שותל / שותלת, not הייתה in this sentence.