hatizokoana ni hatizokoisi wo oku.

A natural reading is:

はちぞこあな に はちぞこいし を おく

Broken down:

• 鉢 = はち
• 底 = そこ / in compounds here it appears as ぞこ
• 穴 = あな
• 石 = いし
• 置く = おく

So:

• 鉢底穴 = はちぞこあな
• 鉢底石 = はちぞこいし

The ぞ in はちぞこ is a common sound change in compounds.

Japanese is normally written without spaces:

鉢底穴に鉢底石を置く。

The spaces here are almost certainly just for learners, to make the parts easier to see:

• 鉢底穴
• に
• 鉢底石
• を
• 置く

So the spaced version is a teaching aid, not standard formatting.

The subject is omitted because Japanese often leaves out information that is obvious from context.

This kind of sentence is very common in:

• instructions
• manuals
• recipes
• gardening directions

So the implied meaning is something like:

• [You] place the drainage stones in/on the pot-bottom hole area
• or Place drainage stones at the drainage hole

Japanese does not need to explicitly say you here. In instructional style, the action is the important part.

Also, 置く is in plain dictionary form, which is often used in short instructions and labels.

に marks the place where something is put or ends up.

With verbs like 置く, に often indicates the location of placement.

So here:

• 鉢底穴に = at / in / on the drainage hole area

A useful pattern is:

• 場所 に 物 を 置く
• put an object in/on/at a place

So the sentence structure is very straightforward:

• 鉢底穴に = location
• 鉢底石を = thing being placed
• 置く = place/put

を marks the direct object of the verb.

Here, the thing being placed is 鉢底石, so it takes を.

In other words:

• 鉢底石を置く = place the drainage stones

This is one of the most basic Japanese patterns:

• object + を + verb

Examples:

• 本を読む = read a book
• 椅子を置く = place a chair
• 鉢底石を置く = place drainage stones

Because Japanese very often makes compound nouns by putting nouns together directly.

So:

• 鉢底穴 literally combines pot + bottom + hole
• 鉢底石 literally combines pot + bottom + stone

This style is compact and very common in technical, product, and instructional language.

You could express the idea more analytically with の, for example:

• 鉢の底の穴
• 鉢の底に入れる石

But compounds like 鉢底穴 and 鉢底石 sound more like fixed terms or item names.

So the no-の version is more concise and more natural in this kind of context.

置く means to put/place something somewhere, often with a sense of setting it down in position.

That works well here because the stones are being placed at the bottom/drainage-hole area of the pot.

If you used 入れる, that would emphasize putting something into a container. That is not impossible in some contexts, but 置く is more natural when the focus is on arranging or laying the stones in position.

So the nuance is roughly:

• 置く = place/set down
• 入れる = put in/insert

In potting instructions, 置く fits the idea of deliberately positioning the stones.

It is a complete sentence, but it has a very instructional feel.

Japanese often uses the plain dictionary form in short directions:

• 水を入れる。
• 土を入れる。
• 苗を植える。

Likewise:

• 鉢底穴に鉢底石を置く。

In English, this kind of wording often corresponds to an instruction like:

• Place drainage stones over the drainage hole.

So although it looks a little bare, it is perfectly normal as a short manual-style sentence.

Yes. That would also be grammatical.

Both of these are fine:

• 鉢底穴に鉢底石を置く
• 鉢底石を鉢底穴に置く

Japanese word order is flexible as long as the particles make the roles clear.

The version with 場所 に first can feel especially natural in step-by-step instructions, because it sets the location first and then says what to place there.

So:

• 鉢底穴に = at the drainage hole
• 鉢底石を = the drainage stones
• 置く = place

That ordering is very easy to process in instructional language.

Strictly speaking, 鉢底穴 refers to the drainage hole in the bottom of the pot.

But in practical instructions like this, Japanese can use the location term a little broadly. The meaning is not usually that you somehow place the stones inside the tiny hole itself; rather, you place them at/over the drainage hole area so drainage works properly.

So grammatically it says to the pot-bottom hole, but in real-world use the intended interpretation is often more practical than literal.

This is very common in instruction language: the wording is compact, and the reader is expected to understand the real-world action.

Japanese nouns usually do not mark singular vs. plural explicitly.

So 鉢底石 can mean:

• a drainage stone
• drainage stones

The exact number comes from context.

In gardening, this usually refers to some drainage stones/gravel, not just one stone. But Japanese leaves that unstated unless the number matters.

That is normal. Japanese often relies on context instead of grammatical number.