Kořenový bal je v substrátu.

Because kořenový agrees with bal in gender, number, and case.

Here, bal is:

• masculine
• singular
• nominative (because it is the subject of the sentence)

So the adjective also takes the masculine singular nominative ending -ý:

• kořenový bal = root ball

If the noun changed, the adjective would change too. For example, in another case or with a different gender, the ending would be different.

It is in the nominative singular.

That is because kořenový bal is the subject of the sentence — the thing that is somewhere.

You can think of the sentence structure as:

• Kořenový bal = subject
• je = is
• v substrátu = in the substrate / growing medium

So the basic pattern is:

• [subject in nominative] + je + [location phrase]

Because the preposition v means in here, and when it expresses location, it normally requires the locative case.

So:

• dictionary form: substrát
• after v for location: v substrátu

This is a very common Czech pattern:

• v domě = in the house
• v obchodě = in the shop
• v substrátu = in the substrate

So the ending changes because the noun is not standing alone — it is governed by the preposition v.

Because substrát is a masculine inanimate noun, and in the locative singular it takes the ending -u here.

So:

• substrát = nominative singular
• v substrátu = locative singular

This kind of change is normal in Czech declension. English learners often need to get used to the idea that nouns change form depending on their role in the sentence.

Je is the 3rd person singular form of the verb být (to be).

So:

• jsem = I am
• jsi / jste = you are
• je = he/she/it is

In this sentence, je means is:

• Kořenový bal je v substrátu. = The root ball is in the substrate.

In a normal full sentence like this, no — you normally keep je.

Czech can sometimes omit forms of to be in special styles, notes, headlines, or very informal fragments, but in an ordinary sentence like this, je is expected.

So the natural standard form is:

• Kořenový bal je v substrátu.

Because Czech does not have articles like English a/an and the.

So kořenový bal can mean:

• a root ball
• the root ball

Which one is meant depends on the context.

In a practical or descriptive sentence like this, English often uses the, but Czech simply does not need a separate word for it.

It can change.

The neutral order here is:

• Kořenový bal je v substrátu.

But Czech word order is more flexible than English, because case endings show the grammatical relationships.

For example, you could also say:

• V substrátu je kořenový bal.

This still means basically the same thing, but the emphasis changes. That version puts more focus on where the root ball is.

So:

• Kořenový bal je v substrátu. = neutral, subject first
• V substrátu je kořenový bal. = more emphasis on location

Yes, it is a normal compound-like noun phrase in gardening and plant care.

Literally:

• kořenový = root-related / root
• bal = ball

Together:

• kořenový bal = root ball

So although it is grammatically an adjective + noun combination, in meaning it functions very much like a set term.

Not always exactly.

In gardening Czech, substrát usually means a growing medium or potting substrate, not necessarily ordinary natural soil.

Depending on context, it may refer to:

• potting mix
• planting medium
• horticultural substrate

So English soil is sometimes close, but substrate / growing medium is often more precise.

V is used because the sentence expresses location inside something:

• v substrátu = in the substrate

If you wanted to express movement into the substrate, Czech would usually use a different construction, often with do + genitive:

• dát něco do substrátu = to put something into the substrate

So this is an important contrast:

• v + locative = location, being in
• do + genitive = movement into

In your sentence, the root ball is already there, so v substrátu is correct.

The difficult sound is ř, which is a special Czech consonant.

A rough guide:

• kořenový sounds approximately like ko-rzhe-no-vee, though that is only an approximation
• je sounds like ye
• substrátu has a long á, so that syllable is held a bit longer

About ř:

• it is not the same as English r
• it is not the same as ž
• it is a specifically Czech sound, something like a rolled or raised r with friction

Learners usually need time to master it, so not producing it perfectly right away is completely normal.

You usually learn the gender together with the noun.

In this sentence, you can also see clues from agreement:

• kořenový has a masculine nominative singular ending
• that matches bal

So the phrase itself shows that bal is being treated as a masculine singular noun.

In dictionary form, Czech nouns are generally learned with their gender because it affects:

• adjective endings
• pronouns
• some numeral forms
• declension patterns

Yes, fairly closely:

• kořenový = root
• bal = ball
• je = is
• v = in
• substrátu = substrate / growing medium

So the structure maps quite neatly onto English:

• Kořenový bal je v substrátu.
• The root ball is in the substrate.

That said, the Czech sentence works without articles, and substrát may be more technical than everyday English soil, so a perfectly natural translation may vary depending on context.