Trasplanta la plántula sin que caiga al suelo.

Yes. In this sentence, trasplanta is an affirmative command directed at tú (informal singular you).

• trasplantar = to transplant
• trasplanta = transplant!

So the sentence is giving an instruction, like something you might read in a gardening guide.

If it were formal you (usted), it would be trasplante.

Because standard Spanish usually uses trasplantar for to transplant. English has transplant, but Spanish often has related words with tras-.

So for a learner, the safest choice is:

• trasplantar = to transplant
• trasplanta = transplant

This is one of those cases where the Spanish word looks similar to English, but not exactly the same.

Plántula means seedling or young plant. It refers to a very small plant, especially one that has recently sprouted and is ready to be moved or replanted.

So in a gardening context:

• planta = plant
• plántula = seedling / very young plant

It is a more specific and technical word than just planta.

The accent mark shows the stress: PLÁN-tu-la.

Spanish spelling rules require an accent mark on words stressed on the third-to-last syllable. Words like that are called esdrújulas, and they always take a written accent.

So:

• plántula is stressed on plán
• therefore it must be written with an accent

Spanish often uses the definite article (el, la, los, las) in instructions when referring to the specific item being handled.

Here, la plántula means something like:

• the seedling
• or in natural English, sometimes just the seedling you are working with

Even if English might say a seedling in some situations, Spanish often prefers la plántula when the object is understood from context.

Because the sentence introduces a whole new clause: that it not fall to the ground.

Compare these two patterns:

• sin + infinitive = when there is no separate conjugated verb
  Example: sin tocarla = without touching it

• sin que + subjunctive = when a new clause with its own verb is introduced
  Example: sin que caiga = without it falling / without letting it fall

In this sentence, the falling is a separate action involving the seedling, so Spanish uses sin que + subjunctive.

Because sin que normally triggers the subjunctive.

After sin que, Spanish usually uses the subjunctive because the action is not being presented as a fact. It is something to avoid, prevent, or keep from happening.

So:

• sin que caiga al suelo = without it falling to the ground
• the fall is not described as real or completed
• it is a possible event the speaker wants to prevent

That is why caiga is used instead of an indicative form like cae.

Caiga is the present subjunctive form of caer.

The verb caer is irregular in the subjunctive because it is based on the yo form of the present indicative:

• yo caigo
• remove -o
• add subjunctive endings
• result: caiga, caigas, caiga, caigamos, caigáis, caigan

So here:

• que caiga = that it fall

The implied subject is la plántula.

So the meaning is:

• transplant the seedling
• without the seedling falling to the ground

Spanish often leaves the subject unstated when it is clear from context. The verb form caiga could grammatically go with several subjects, but here the obvious one is la plántula.

Al suelo means to the ground or onto the ground.

The word al is the contraction of:

• a + el = al

So:

• a el suelo is not used
• Spanish contracts it to al suelo

Also, suelo can mean floor or ground, depending on context. In a gardening sentence like this, ground is the most natural translation.

Yes, you may hear sin que se caiga al suelo, and it sounds natural in many varieties of Spanish.

The difference is subtle:

• caer = to fall
• caerse = to fall down / to fall accidentally

In practical use, caerse often sounds a bit more everyday or emphasizes the accidental nature of the fall. But in an instruction like this, plain caiga is perfectly correct and slightly more neutral or concise.