Έχω έναν σπόρο και θέλω να τον φυτέψω σε άλλη γλάστρα.

Because σπόρος is a masculine noun, and Greek words have to agree in gender, number, and case.

Here the phrase is the direct object of έχω, so it must be in the accusative singular:

• nominative: ένας σπόρος = a seed
• accusative: έναν σπόρο = a seed

So έναν σπόρο is the correct form in this sentence.

Because Greek changes noun endings depending on their role in the sentence.

The basic dictionary form is ο σπόρος. But after a verb like έχω when the noun is the thing being had, it becomes a direct object, so Greek uses the accusative:

• ο σπόρος = the seed
• τον σπόρο = the seed, as object

So in Έχω έναν σπόρο, the noun changes from σπόρος to σπόρο because it is the object of έχω.

You normally learn Greek nouns together with their article:

• ο σπόρος = seed

The article ο tells you the noun is masculine. That matters because other words referring to it must match:

• έναν σπόρο
• τον
• potentially adjectives in masculine forms too

So even though seed is not biologically male, Greek still treats σπόρος as grammatically masculine.

Να introduces the verb that follows θέλω.

A very common Greek pattern is:

• θέλω να + verb

This means I want to + verb.

So:

• θέλω να φυτέψω = I want to plant
• θέλω να τον φυτέψω = I want to plant it

English uses to here, but Greek uses να plus a specific verb form.

Φυτέψω is the 1st person singular aorist subjunctive form of φυτεύω.

In practical learner terms, after να, Greek often uses this kind of form to talk about a single, complete action:

• να φυτέψω = to plant / that I plant, as one complete act

That fits this sentence well, because planting a seed in another pot is seen as one action.

Compare:

• θέλω να φυτέψω τον σπόρο = I want to plant the seed
• φυτεύω by itself is the present/basic stem, more like I plant / I am planting

Τον means him/it in the masculine accusative singular. Here it means it and refers back to τον σπόρο.

So the structure is:

• έναν σπόρο = a seed
• να τον φυτέψω = to plant it

Greek pronouns must match the grammatical gender of the noun they replace. Since σπόρος is masculine, the pronoun is τον.

Because object pronouns in Modern Greek are usually clitics, and they normally come before the verb.

So Greek says:

• να τον φυτέψω

not:

• να φυτέψω τον (wrong in this use)

This is very normal Greek word order for short object pronouns:

• τον βλέπω = I see him/it
• θα το κάνω = I will do it
• θέλω να τον φυτέψω = I want to plant it

Not if you want the sentence to mean the same thing.

Without τον, the verb φυτέψω no longer has its object stated, so the sentence sounds incomplete unless the object is extremely obvious from context.

You could say:

• Θέλω να φυτέψω τον σπόρο σε άλλη γλάστρα
  This repeats the noun instead of using the pronoun.

Or:

• Έχω έναν σπόρο και θέλω να τον φυτέψω σε άλλη γλάστρα
  This is smoother, because the noun is mentioned once and then replaced by τον.

Both are possible, but they feel slightly different.

• σε άλλη γλάστρα = into another pot
• σε μια άλλη γλάστρα = into another pot, with a bit more explicit indefiniteness, similar to into some other pot / into another pot

In many cases Greek can omit the indefinite article where English would still use a or another. So σε άλλη γλάστρα sounds natural and concise.

After σε, Greek uses the accusative.

The noun γλάστρα is feminine, and in the singular its nominative and accusative forms are often the same:

• nominative: η γλάστρα
• accusative: τη γλάστρα

Without the article, you just see γλάστρα, so the case is not obvious from the ending alone. But grammatically, after σε, it is accusative.

Άλλη means other / another, and it agrees with γλάστρα, which is a feminine singular noun.

So:

• masculine: άλλος
• feminine: άλλη
• neuter: άλλο

Since γλάστρα is feminine, Greek uses άλλη γλάστρα.

In this sentence, άλλη is best understood as another.

Not completely. Greek word order is more flexible than English, but the given version is very natural.

The sentence:

• Έχω έναν σπόρο και θέλω να τον φυτέψω σε άλλη γλάστρα.

is a neutral, standard way to say it.

You might also hear slight variations for emphasis, such as moving σε άλλη γλάστρα later or earlier in conversation, but the basic order here is the safest one for a learner.

The main thing that is not flexible here is the clitic pronoun placement: τον normally stays before φυτέψω.