Nous allons planter des fleurs dans le jardin demain.

Nous allons planter is the near future in French: aller + infinitive. It is very common and often corresponds to English we are going to plant.

French could also use the simple future: Nous planterons des fleurs dans le jardin demain. That would also be correct. In everyday speech, though, the near future is extremely common, especially when talking about a planned action.

Allons is the nous form of the verb aller (to go) in the present tense.

The full present-tense forms are:

• je vais
• tu vas
• il/elle/on va
• nous allons
• vous allez
• ils/elles vont

In this sentence, allons does not literally mean go by itself. Together with planter, it forms the near future: are going to plant.

After aller in the near future structure, the main verb stays in the infinitive.

So:

• nous allons planter = we are going to plant
• je vais manger = I am going to eat
• ils vont venir = they are going to come

You do not conjugate the second verb here.

Des fleurs is the indefinite plural article, meaning some flowers.

• des fleurs = some flowers / flowers in general
• les fleurs = the flowers, specific flowers already known
• de fleurs would usually appear in other structures, not normally here by itself

So planter des fleurs means planting some flowers, without specifying exactly which ones.

Because the sentence is talking about planting flowers, not just one flower.

In French, plural nouns usually take -s in writing:

• une fleur = a flower
• des fleurs = flowers / some flowers

The -s is usually not pronounced, but it still has to be written.

Dans means in or inside, and le jardin means the garden. So dans le jardin means in the garden.

French often uses dans for location inside a space:

• dans la maison = in the house
• dans le parc = in the park
• dans le jardin = in the garden

It is the natural choice here for where the planting will happen.

After dans, French uses the article directly: dans le jardin.

Au jardin can exist in French, but it is used in different contexts and is much less natural for this sentence. If you want to say in the garden as the location of the action, dans le jardin is the standard expression here.

French often puts time expressions like demain at the end of the sentence, especially in neutral word order.

So this structure is very common:

• subject + verb + object + place + time

Here:

• Nous = subject
• allons planter = verb phrase
• des fleurs = object
• dans le jardin = place
• demain = time

French can also move demain to the beginning for emphasis:

• Demain, nous allons planter des fleurs dans le jardin.

Yes, absolutely. That is correct and natural.

Putting demain first can give slightly more emphasis to the time:

• Nous allons planter des fleurs dans le jardin demain.
• Demain, nous allons planter des fleurs dans le jardin.

Both mean the same thing overall.

Yes. In everyday spoken French, on va planter des fleurs dans le jardin demain is extremely common.

Although on literally often means one, it very often means we in spoken French. So:

• nous allons = more formal or careful standard French
• on va = very common in conversation

Both are correct.

In careful pronunciation, Nous allons planter des fleurs dans le jardin demain is approximately:

noo zah-lon plahn-tay day flur dahn luh zhar-dan duh-man

A few useful points:

• The s in nous is normally silent, but it links before allons, so you hear z: nous allons.
• The final -s in fleurs is silent.
• The n in dans and jardin is part of a nasal sound, not a fully pronounced n.
• The final letters in French are often silent, so pronunciation does not always match spelling closely.

Yes, many speakers pronounce des as day here.

That is because when des is an article before a plural noun, it is often pronounced like dé:

• des fleurs sounds like day flur

This is normal and standard in speech.

The sentence follows a very common French order:

subject + verb phrase + object + place + time

So here:

• Nous = subject
• allons planter = verb phrase
• des fleurs = object
• dans le jardin = place
• demain = time

This order is very useful for building your own French sentences.

No. In standard French, the subject pronoun is normally required.

So you say:

• Nous allons planter... not just
• Allons planter...

The only exception is special structures such as commands:

• Allons planter des fleurs ! = Let’s plant flowers!

But in a normal statement, you need the subject pronoun.

It is mostly neutral standard French.

Nous allons planter des fleurs dans le jardin demain sounds correct and natural in writing and speech, though in casual conversation many speakers would prefer On va planter des fleurs dans le jardin demain.

So this sentence is a good model of standard French, while on va is often more conversational.