Орхидея начала вянуть, потому что почва была слишком сухой.

Because орхидея is a feminine noun.

In the past tense, Russian verbs agree with the subject in gender and number:

• masculine: начал
• feminine: начала
• neuter: начало
• plural: начали

So:

• орхидея начала = the orchid began

If the subject were masculine, for example цветок (flower), you would say цветок начал.

After начать / начать (to begin / to start), Russian usually uses an infinitive, just like English does in began to wilt.

So:

• начала вянуть = began to wilt

Here:

• начала tells you that the action of beginning happened
• вянуть names the action that began

This is a very common pattern:

• начал работать = began to work
• начала плакать = began to cry
• начали расти = began to grow

Вянуть means to wilt, to droop, or to lose freshness, especially for plants or flowers.

So орхидея начала вянуть means the orchid started showing signs of becoming unhealthy and droopy.

It is different from stronger verbs like:

• засохнуть = to dry out completely
• умереть = to die

So вянуть suggests an earlier stage in the problem.

Because потому что introduces a subordinate clause, meaning because.

The sentence has two parts:

• Орхидея начала вянуть
• потому что почва была слишком сухой

In Russian, a clause introduced by потому что is normally separated by a comma.

So this is standard punctuation:

• ..., потому что ...

It means because.

Literally, the parts are:

• потому = for that reason / therefore
• что = that

But as a fixed expression, потому что simply means because.

You should learn it as one common connector:

• Я ушёл, потому что устал. = I left because I was tired.
• Она молчала, потому что не знала ответа. = She was silent because she didn’t know the answer.

Because the subject of that clause is почва (soil), which is feminine singular.

Russian past-tense forms of быть agree with the subject:

• был = masculine
• была = feminine
• было = neuter
• были = plural

So:

• почва была = the soil was

This is a very common learner question.

In sentences with быть in the past or future, a full adjective used as the predicate is often put in the instrumental case.

So:

• почва была сухой = the soil was dry

Here:

• сухой is the feminine singular instrumental form of сухой

This pattern is very common and very safe to use:

• вода была холодной = the water was cold
• комната была тёмной = the room was dark

You may also encounter other possibilities in Russian, such as short-form adjectives, but была сухой is a standard, natural choice.

Слишком means too in the sense of excessively.

So:

• слишком сухой = too dry

It usually goes before the adjective or adverb it modifies:

• слишком дорогой = too expensive
• слишком быстро = too fast

In this sentence, it modifies сухой.

Because Russian has no articles.

English distinguishes between:

• an orchid
• the orchid

Russian usually does not mark that difference with a separate word. The meaning comes from context.

So орхидея can mean:

• an orchid
• the orchid

depending on the situation.

The same is true for почва:

• soil
• the soil

Not completely. Russian word order is more flexible than English word order.

The neutral order here is:

• Орхидея начала вянуть, потому что почва была слишком сухой.

But Russian can move things around for emphasis. For example:

• Потому что почва была слишком сухой, орхидея начала вянуть.

This means the same thing, but it puts the reason first.

Even inside the clause, word order can shift a little depending on emphasis, though the original sentence is the most natural neutral version.

Because the two verbs are doing different jobs.

• начала comes from начать, a perfective verb
• вянуть is an infinitive describing an ongoing process

The perfective начала is used because the sentence refers to the moment when the wilting started. That starting point is seen as a single completed event.

But вянуть itself describes a process, so the infinitive is the normal form here.

This combination is very common in Russian:

• начал читать = began reading
• начала писать = began writing
• начали болеть = started hurting / aching

The stress pattern is important in Russian. In this sentence:

• орхидЕя
• началА
• вЯнуть
• потомУ что
• пОчва
• былА
• слИшком
• сухОй

A rough pronunciation guide:

• орхидЕя ≈ or-khee-DYE-ya
• началА ≈ na-cha-LA
• вЯнуть ≈ VYA-nut’
• пОчва ≈ POCH-va
• сухОй ≈ su-KHOY

Stress is worth memorizing together with each word, especially for past tense forms like начала.

Yes. Russian has several natural alternatives, depending on nuance.

For example:

• Орхидея стала вянуть, потому что почва была слишком сухой.
  = The orchid started to wilt because the soil was too dry.

• Орхидея начала засыхать, потому что почва была слишком сухой.
  = The orchid began to dry out because the soil was too dry.

The original начала вянуть is a very natural choice if you want to describe the orchid beginning to lose freshness and droop.