Перед тим як садити розсаду, ми кладемо компост на грядку.

It means before or before doing something.

In this sentence:

• Перед тим як садити розсаду = Before planting the seedlings

Literally, перед = before, тим = that, and як = how/as/when, but as a whole it functions like a fixed expression meaning before.

Because Ukrainian often uses the infinitive after expressions like перед тим як when the action is being described in a general way.

So:

• садити = to plant
• перед тим як садити розсаду = before planting seedlings

English often uses -ing here (before planting), but Ukrainian commonly uses the infinitive.

Садити is imperfective, while посадити is perfective.

Here, садити fits well because the sentence sounds like a general or habitual action:

• Before planting seedlings, we put compost on the bed.

That is, this is what we normally do.

If you wanted to focus on one completed planting event, посадити could also appear in some contexts:

• Перед тим як посадити розсаду... = Before planting / before we plant the seedlings

So the difference is mainly about aspect:

• садити = planting as a process / repeated action
• посадити = to plant successfully, as a completed act

Because it is in the accusative singular.

The dictionary form is:

• розсада = seedlings / young plants for transplanting

After the verb садити (to plant), it becomes the direct object, so Ukrainian uses the accusative:

• розсада → розсаду

This is a very common pattern for feminine nouns ending in -а:

• nominative: книга
• accusative: книгу

Because компост is a masculine inanimate noun, and in the singular its accusative usually looks the same as its nominative.

So:

• nominative: компост
• accusative: компост

It is still the direct object of кладемо, but the form does not visibly change.

That is different from розсада → розсаду, where the accusative has a different ending.

Кладемо means we put, we place, or sometimes we are putting, depending on context.

It comes from the verb:

• класти = to put / to place / to lay

So:

• ми кладемо компост = we put compost

In this sentence, it most likely has a habitual meaning:

• we put compost on the bed (as a regular practice)

Yes. Ukrainian often drops subject pronouns because the verb ending already shows the person and number.

• кладемо already means we put

So both of these are possible:

• Ми кладемо компост на грядку.
• Кладемо компост на грядку.

Including ми can add a little clarity, emphasis, or simply sound natural in that context.

Because на can take different cases depending on the meaning.

Here, на грядку uses the accusative because it shows movement or placement onto the bed:

• класти компост на грядку = to put compost onto the bed

If you were talking about location, you would use the locative:

• компост лежить на грядці = the compost is on the bed

So:

• на грядку = onto the bed
• на грядці = on the bed

Грядка means a garden bed, especially a bed where vegetables or other cultivated plants are grown.

Depending on context, it can be translated as:

• garden bed
• vegetable bed
• raised bed (if it is physically raised)

So на грядку here means onto the garden bed.

Because розсада means seedlings / young plants for transplanting, not seeds.

So:

• садити розсаду = to plant seedlings
• сіяти насіння = to sow seeds

You сіяти seeds, but you садити seedlings, potatoes, small plants, trees, and so on.

Yes. Ukrainian word order is fairly flexible.

This sentence starts with the time expression:

• Перед тим як садити розсаду, ми кладемо компост на грядку.

That puts the before planting... part first.

You could also rearrange it, for example:

• Ми кладемо компост на грядку перед тим, як садити розсаду.

That is also natural. The meaning stays basically the same, but the emphasis changes a little.

Because the sentence begins with a subordinate time clause:

• Перед тим як садити розсаду = subordinate clause
• ми кладемо компост на грядку = main clause

In Ukrainian, that clause is separated from the main clause by a comma.

You may also sometimes see перед тим, як written with a comma inside the expression in other sentences or styles. For a learner, the most important thing is to recognize the structure and meaning: before doing X, we do Y.