one rotation of its sun
blue paper
It is the rotation of the planet one complete revolution that determines the length of a day.
How long it spins on it's axis
A planet's rotation on its axis determines the length of its day.
The planet is Mercury. (Some people think it is Venus, but it is Mercury.)
It completes one rotation in a sidereal day.
Mercury. It has the longest cycle of ALL the planets, not just terrestrial.
its possible but the cycle usually determines when it blooms
Mars. Its day-night cycle is only about 40 minutes longer than Earth's.
Yes. As with just about any planet, Mars has a day and night cycle. For Mars it is about 24 hours and 40 minutes.
its mass
The planet's rotational period is the only thing that determines the length of one day. (mostly - it also is dependent on how fast the planet orbits the sun. If it orbits quickly, the "day" will be measurably less than the time for one full rotation.)