La asociación de cultivos incluye plantas aromáticas.

Because asociación is a feminine noun in Spanish. Nouns ending in -ción are very commonly feminine, so they usually take la in the singular:

• la asociación
• la canción
• la información

So la asociación is the correct form.

In this context, asociación de cultivos refers to the practice of growing different crops together in a planned way. In English, this is often called:

• crop association
• intercropping
• sometimes companion planting, depending on the context

So it is not just a random association in the social sense. Here, it is an agricultural term.

De is often used in Spanish to link two nouns, where English might use:

• of
• a noun used as an adjective
• a compound noun

So:

• asociación de cultivos = association of crops / crop association

This is very common in Spanish:

• casa de campo = country house
• jugo de naranja = orange juice
• centro de salud = health centre

It is plural because the idea involves more than one crop or type of crop. Asociación de cultivos normally refers to combining different crops together, so cultivos in the plural makes sense.

• cultivo = crop / cultivation
• cultivos = crops

Using the singular here would sound different and less natural in this context.

Because the subject is singular: la asociación de cultivos.

Even though cultivos is plural, it is not the main subject. The main noun is asociación, which is singular.

So the structure is:

• La asociación de cultivos = singular subject
• incluye = singular verb
• plantas aromáticas = direct object

This is similar to English:

• The crop association includes aromatic plants.

Not:

• The crop association include...

Spanish often leaves out the article when speaking about things in a general category.

So:

• incluye plantas aromáticas = it includes aromatic plants

This sounds natural when talking generally, not about specific plants already known to the listener.

If you said incluye las plantas aromáticas, that would suggest specific aromatic plants, perhaps ones already mentioned before.

In Spanish, adjectives usually come after the noun.

So:

• plantas aromáticas = aromatic plants

This is the normal word order. English usually does the opposite:

• aromatic plants

Spanish can sometimes place adjectives before the noun, but that often changes the tone or meaning. Here, plantas aromáticas is the standard and natural order.

Because the adjective has to agree with the noun in gender and number.

• planta is feminine singular
• plantas is feminine plural

So the adjective must also be feminine plural:

• planta aromática
• plantas aromáticas

This kind of agreement is a basic rule in Spanish.

It literally means aromatic plants, but in many real-life contexts it can refer to what English speakers often call herbs, especially culinary or medicinal ones such as:

• rosemary
• thyme
• mint
• lavender

So the exact English translation may depend on context. Literally it is aromatic plants, but in gardening or farming it may overlap with herbs.

No, not normally.

The personal a is used before specific people, and sometimes pets or personified beings, but not usually before things or plants.

So you say:

• incluye plantas aromáticas

Not:

• incluye a plantas aromáticas

The sentence follows a very common Spanish pattern:

• Subject: La asociación de cultivos
• Verb: incluye
• Direct object: plantas aromáticas

So it is a straightforward subject + verb + object sentence.

This makes it a useful model for similar sentences, such as:

• La receta incluye tomate.
• El jardín incluye flores.
• El proyecto incluye varias ideas.

Yes. Incluye is the third-person singular present tense form of incluir.

Conjugation in the present:

• yo incluyo
• tú incluyes
• él / ella / usted incluye
• nosotros/as incluimos
• vosotros/as incluís
• ellos / ellas / ustedes incluyen

In the sentence, incluye matches la asociación, which is it.

Yes, it is natural and correct in Spanish from Spain.

The vocabulary is standard, and the sentence sounds like something you might read in:

• gardening advice
• agricultural texts
• educational materials
• sustainability or farming guides

In Spain, depending on the exact context, people might also use related expressions such as cultivos asociados or asociar cultivos, but the original sentence is perfectly normal.