Undervanning gjør plantejorden tørr.

Undervanning means too little watering or underwatering.

It is a compound noun:

• under- = under / too little
• vanning = watering

So the whole word literally means something like insufficient watering. Norwegian very often makes long compound words like this.

Yes, it is understandable and correct, especially in gardening or care instructions. But in very everyday speech, many Norwegians might also say:

• for lite vanning = too little watering
• å vanne for lite = to water too little

So undervanning is fine, but for lite vanning may sound a bit more conversational.

Gjør is the present tense of å gjøre, which often means to do or to make.

In this sentence, it means makes:

• gjør plantejorden tørr = makes the plant soil dry

This is a very common pattern in Norwegian:

• gjøre + something + adjective

For example:

• Det gjør meg glad = It makes me happy
• Sola gjør rommet varmt = The sun makes the room warm

Because Norwegian usually writes compound nouns as a single word.

Here:

• plante = plant
• jord = soil
• plantejord = plant soil / potting soil

Then -en is added for the definite singular:

• plantejord = plant soil / potting soil
• plantejorden = the plant soil / the potting soil

This one-word spelling is very typical in Norwegian.

The ending -en marks the noun as definite singular, roughly like the in English.

So:

• plantejord = plant soil / potting soil
• plantejorden = the plant soil / the potting soil

Norwegian often puts definiteness at the end of the noun instead of using a separate word like English the.

Because Norwegian usually expresses definiteness with an ending on the noun.

So instead of saying a separate word for the, Norwegian often does this:

• en bil = a car
• bilen = the car

Likewise:

• plantejord = potting soil
• plantejorden = the potting soil

That is why you do not need a separate article here.

Because tørr agrees with the noun it describes.

Here, plantejorden is a singular en-word, so the adjective form is:

• tørr

Compare:

• en plantejord er tørr = singular common gender
• et gulv er tørt = singular neuter
• blomstene er tørre = plural

In your sentence, tørr is a predicative adjective: it comes after the verb and describes the result.

This uses the pattern:

subject + gjør + object + adjective

So:

• Undervanning = subject
• gjør = verb
• plantejorden = object
• tørr = adjective describing the result

This is similar to English:

• Underwatering makes the soil dry

The adjective comes after the object because it describes what the object becomes.

Not in this sentence structure.

Here, tørr is a result adjective after gjør, so it must stay after plantejorden:

• Undervanning gjør plantejorden tørr

If you want the adjective directly before the noun, you would need a different structure, for example:

• tørr plantejord = dry potting soil
• den tørre plantejorden = the dry potting soil

So both are possible in Norwegian, but they are used in different sentence patterns.

Because this sentence is a straightforward main clause, and Norwegian often has a similar order to English in simple statements:

subject + verb + object + adjective

So:

• Undervanning = subject
• gjør = verb
• plantejorden = object
• tørr = result adjective

Norwegian does have special word-order rules, especially the verb-second rule, but in a simple sentence like this, the order looks quite English-like.

Sometimes, yes, but the meaning becomes broader or less specific.

• plantejorden specifically means the soil used for plants, often potting soil
• jorden can mean the soil, the ground, or even the Earth, depending on context

So plantejorden is more precise here and is a good choice if you are talking about a plant or flowerpot.

For many English speakers, gjør is one of the trickier words.

A few points:

• ø is not an English vowel; it is somewhat similar to the vowel in French bleu or German schön
• the gj sound is often softened, and in many accents it sounds close to a y-like sound before the vowel

So gjør is often roughly heard like yør, though that is only an approximation.

The exact pronunciation varies a little by dialect, but the important thing is:

• do not pronounce the g like a hard English g
• try to learn the ø sound separately, since it appears in many Norwegian words

Yes. A more expanded version would be:

• Undervanning gjør at plantejorden blir tørr.

This literally adds the idea of causes that the plant soil becomes dry. It is a bit longer and more explicit.

Your original sentence is shorter and perfectly good:

• Undervanning gjør plantejorden tørr.

Both are grammatical; the shorter version is more compact.