kanyousyokubutu ha nedumarisite iru.

It is read:

かんようしょくぶつ は ねづまりして いる。

A few notes:

• 観葉植物（かんようしょくぶつ） = houseplant / foliage plant
• 根詰まり（ねづまり） = being root-bound, roots becoming too crowded in the pot
• している = is doing / is in the state of having done, depending on the verb

In normal Japanese writing, this would usually be written without spaces:

観葉植物は根詰まりしている。

観葉植物 is a compound noun:

• 観葉 = ornamental leaves / leaves appreciated for viewing
• 植物 = plant

So literally it is something like a plant grown for its leaves. In natural English, this is usually houseplant or foliage plant, depending on context.

は marks the topic of the sentence.

So 観葉植物は means something like:

• As for the houseplant, ...
• The houseplant is ...

This sets up 観葉植物 as the thing being talked about, and the rest of the sentence says something about it.

In many cases, は sounds natural when the plant is already known in the conversation, or when the speaker is making a general statement about it.

Yes, 観葉植物が根詰まりしている。 is possible.

The difference is mainly about focus:

• 観葉植物は根詰まりしている。
  = speaking about the houseplant as a topic: As for the houseplant, it is root-bound.
• 観葉植物が根詰まりしている。
  = puts more focus on the houseplant as the thing that is root-bound: It’s the houseplant that’s root-bound / The houseplant is root-bound.

Very roughly:

• は = topic / contrast / known item
• が = subject focus / new information / identification

根詰まり is a noun meaning root congestion or being root-bound.

It is made from:

• 根（ね） = root
• 詰まり（つまり） = clogging, being packed, blockage

In gardening Japanese, 根詰まりする means a plant’s roots have filled the pot so much that growth is restricted. So 根詰まり is a very natural word in this context.

Here, 根詰まり behaves like a suru-verb noun.

That means it can combine with する:

• 根詰まりする = to become root-bound

So:

• 根詰まりしている = is root-bound / has become root-bound and is in that state

This is very common in Japanese. Many nouns can become verbs with する.

Great question. Here, している does not mean an ongoing action in the English sense of is doing.

With many Japanese verbs, 〜ている can also show the resulting state after a change.

So:

• 根詰まりする = to become root-bound
• 根詰まりしている = to be in the state of having become root-bound

So the natural English meaning is:

• is root-bound

not

• is becoming root-bound right now

This is a very common use of 〜ている in Japanese.

Yes, and it is closely related.

• 根が詰まっている = the roots are packed/clogged
• 根詰まりしている = is root-bound

The first version describes the condition more literally.
The second is a more set, gardening-style expression.

So 根詰まりしている sounds very natural when talking about plants in pots.

Because there is no direct object here.

This sentence is not saying that the plant is doing something to another thing. Instead, it describes the plant’s condition:

• 観葉植物 = topic
• 根詰まりしている = is root-bound

The idea of roots being crowded is already built into the word 根詰まり, so you do not need a separate object.

Not necessarily. Japanese nouns usually do not show singular vs. plural unless the context makes it clear.

So 観葉植物は根詰まりしている could mean:

• The houseplant is root-bound
• Houseplants are root-bound

However, in many everyday situations, it will most naturally be understood as the houseplant is root-bound, especially if you are talking about one specific plant.

Yes, it is natural, especially in contexts like:

• talking about why a plant is not growing well
• explaining that a plant needs repotting
• commenting on the condition of a plant

For example, someone might say this after looking at the pot and roots.

It has a slightly explanatory feel, like:

• As for the houseplant, it’s root-bound.

Usually, no. Standard Japanese is normally written without spaces between words.

So the normal written form is:

観葉植物は根詰まりしている。

Spaces are often added in learning materials to make the structure easier to see.

The underlying verb is:

根詰まりする

And the sentence uses its 〜ている form:

• する
• して
• している

So the pattern is:

• 根詰まりする = to become root-bound
• 根詰まりしている = to be root-bound

You could say:

観葉植物は根詰まりした。

That means:

• The houseplant became root-bound.

Compare:

• 根詰まりした = became root-bound
• 根詰まりしている = is root-bound

So 〜した focuses on the event/change, while 〜している focuses on the resulting state.