Dès qu’il fait un peu plus chaud, les enfants se mettent à semer des graines partout dans le potager.

Dès que means as soon as or once.

It introduces the moment that triggers the main action:

• Dès qu’il fait un peu plus chaud = As soon as it gets a little warmer

Compared with plain quand (when), dès que often feels more immediate: one thing happens right after the other.

This is because of elision.

When que comes before a word starting with a vowel sound, the e drops:

• que il → qu’il

This is very common in French:

• que elle → qu’elle
• que on → qu’on

So dès qu’il is just the normal written form.

French often uses the impersonal expression il fait + adjective/noun for weather and temperature.

So:

• il fait chaud = it is hot / the weather is warm
• il fait froid = it is cold
• il fait beau = the weather is nice

The il here does not refer to a real person or thing. It is just the standard impersonal subject, like it in it is raining.

Un peu plus chaud means a little warmer.

Breakdown:

• plus chaud = warmer
• un peu = a little

So:

• il fait plus chaud = it’s warmer
• il fait un peu plus chaud = it’s a little warmer

This does not necessarily mean hot. It only means the temperature has gone up somewhat compared with before.

The present tense is being used for a habitual or general situation.

The sentence means something like:

• Whenever it gets a bit warmer, the children start sowing seeds all over the vegetable garden.

So this is not necessarily one single event happening right now. It describes what typically happens under those conditions.

French often uses the present this way for routines, habits, and general truths.

Se mettre à + infinitive means to start doing something or to begin doing something.

Here:

• les enfants se mettent à semer = the children start sowing

It is a very common structure in French.

Other examples:

• Il se met à rire. = He starts laughing.
• Nous nous mettons à travailler. = We start working.

It often suggests the action begins quite suddenly or actively.

Because se mettre à is a fixed idiomatic expression meaning to start doing something.

Without the reflexive pronoun, mettre usually means to put:

• mettre un livre sur la table = to put a book on the table

But with se mettre à, the meaning changes:

• se mettre à lire = to start reading
• se mettre à courir = to start running

So the reflexive is not optional here. It is part of the expression.

Because semer means to sow seeds, which fits perfectly with des graines.

• semer des graines = to sow seeds

This is more precise than planter in this context.

A useful distinction:

• semer = to sow seeds
• planter = to plant something in the ground, often a plant, seedling, tree, etc.

So if the object is specifically graines, semer is especially natural.

Because this is a normal positive sentence with an indefinite plural direct object.

• des graines = some seeds

French uses des here because the children are sowing seeds, not a specific identified set.

You often get de instead of des in other situations, for example:

• after negation: Ils ne sèment pas de graines.
• after quantity expressions: beaucoup de graines

But in this sentence, des graines is exactly what you would expect.

Dans le potager just means in the vegetable garden.

Partout dans le potager adds the idea of everywhere / all over the vegetable garden.

So:

• dans le potager = location
• partout dans le potager = location + spread/scattering throughout it

This makes the sentence more vivid: the children are not sowing in one neat spot, but all over the place.

Le potager refers to a specific vegetable garden, one that is understood in the context.

So it suggests something like:

• the vegetable garden
• the one at the house, school, or place already known to the speaker and listener

If it said un potager, it would mean a vegetable garden, with a less specific feel.

Les enfants means the children and usually refers to a specific group already known in the context.

• les enfants = the children
• des enfants = some children

So this sentence sounds like it is talking about a particular set of children, not just any random children.

Yes, but the meaning would change slightly.

• Dès qu’il fait un peu plus chaud... describes a habitual situation: whenever it gets warmer, this happens.
• Dès qu’il fera un peu plus chaud... would point to a specific future moment: as soon as it gets a bit warmer, this will happen.

A useful grammar point: after dès que, French uses the indicative, not the subjunctive. So a future form like fera is possible when you are talking about an actual future event.