Если почва слишком сухая, даже фикус начинает вянуть.

In Russian, the verb to be is usually omitted in the present tense.

So:

• почва слишком сухая = the soil is too dry

But in the past or future, Russian does use forms of быть:

• Почва была слишком сухая = The soil was too dry
• Почва будет слишком сухая = The soil will be too dry

So the missing is is completely normal.

Because сухая is an adjective agreeing with почва.

• почва is feminine
• it is singular
• it is in the nominative case here

So the adjective must match:

• сухой = masculine/in some oblique forms
• сухая = feminine singular nominative
• сухое = neuter singular nominative
• сухие = plural nominative

This is one of the most important features of Russian grammar: adjectives change to match the noun.

Слишком means too in the sense of more than is acceptable / excessively.

So:

• слишком сухая = too dry
• очень сухая = very dry

That distinction matters. Очень сухая just describes the degree. Слишком сухая suggests a problem.

In this sentence, the meaning is not just that the soil is dry, but that it is dry to an unhealthy extent.

Both can sometimes be translated as soil or earth, but they are not identical.

• почва = soil in a more botanical, agricultural, or scientific sense
• земля = earth, ground, land, soil in a broader everyday sense

In a plant-care sentence, почва sounds especially natural because it refers to the growing medium of the plant.

So Если почва слишком сухая... feels a bit more precise than Если земля слишком сухая...

Because Если почва слишком сухая is a subordinate clause introduced by если.

Russian normally separates this kind of clause with a comma:

• Если почва слишком сухая, даже фикус начинает вянуть.

This is true whether the if-clause comes first or second:

• Если почва слишком сухая, ...
• ..., если почва слишком сухая.

Russian punctuation is generally stricter than English here.

Если means if, so it introduces a condition.

• Если почва слишком сухая... = If the soil is too dry...

Когда means when, so it introduces a time relationship.

• Когда почва слишком сухая... would mean something more like When the soil is too dry...

In some contexts, English can use when and if somewhat loosely, but Russian keeps the distinction clearer. Here the idea is conditional: dryness causes the plant to wilt. So если is the right choice.

Даже means even.

It emphasizes that the result is surprising or stronger than expected:

• даже фикус = even a ficus

The idea is that a ficus is considered fairly hardy, so if the soil is too dry, even such a plant starts to wilt.

So даже adds emphasis and a kind of contrast: not only delicate plants, but even a ficus.

Both are possible, but they mean slightly different things.

• вянет = wilts / is wilting
• начинает вянуть = begins to wilt / starts wilting

The version with начинает focuses on the start of the process. It suggests the first visible sign of trouble.

So:

• Если почва слишком сухая, фикус вянет = If the soil is too dry, the ficus wilts / is wilting.
• Если почва слишком сухая, фикус начинает вянуть = If the soil is too dry, the ficus starts to wilt.

The sentence you were given is a bit more nuanced and descriptive.

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

It describes the plant becoming limp because it lacks enough water or is otherwise unhealthy.

It is different from some related verbs:

• вянуть = to wilt
• засыхать = to dry out
• увядать = to fade/wilt, often used with flowers and sometimes a bit more literary

So in this sentence, вянуть is a very natural verb for what a plant does when the soil is too dry.

Because фикус is the subject of the main clause:

• даже фикус начинает вянуть

The ficus is the thing that begins to wilt, so it appears in the nominative case.

Also note that Russian has no articles, so фикус could correspond to:

• a ficus
• the ficus

The exact English choice depends on context. In this kind of general statement, English often uses a ficus or simply ficus in a generic sense.

It is most naturally understood as a general truth or habitual fact.

Russian often uses the present tense for this kind of statement:

• Если почва слишком сухая, даже фикус начинает вянуть.

That means something like:

• whenever the soil gets too dry, this is what happens

So the present tense here does not have to mean right now. It can express a general pattern.

Yes, Russian word order is fairly flexible, though the emphasis changes.

The original sentence:

• Если почва слишком сухая, даже фикус начинает вянуть.

A possible alternative:

• Даже фикус начинает вянуть, если почва слишком сухая.

The basic meaning stays the same. The difference is mainly in focus:

• starting with Если... presents the condition first
• starting with Даже фикус... emphasizes the surprising subject first

One important detail: даже usually goes right before the word it emphasizes, so даже фикус means even a ficus.

Because its subject, фикус, is singular.

• фикус начинает = the ficus begins
• фикусы начинают = the ficuses begin

Russian verbs in the present tense agree with the subject in number and person.

Here:

• фикус = third person singular
• therefore начинает = third person singular

The stresses are:

• е́сли
• по́чва
• сли́шком
• суха́я
• да́же
• фи́кус
• начина́ет
• вя́нуть

So the whole sentence with stress marks is:

Е́сли по́чва сли́шком суха́я, да́же фи́кус начина́ет вя́нуть.

This is useful because Russian stress is unpredictable and can affect pronunciation a lot.