If there aren't pronounced seasonal changes in a year, would people really keep track of things by years? You might look at how Earth people living on say tropical islands keep track of things. Or you could give your planet a moon (or more than one), and use that for keeping track.

You're asking "how do I make the seasons change faster" but it sounds like the underlying question is more like "how can I justify measuring time on a scale shorter than ~7 years".

@Salda007 Hm, fair point.

I honestly find the concept of almost 7 times longer years compared to earth interesting and would encourage you to keep it that way. It just highlights the unique aspects of the planet and setting so well. And to your worries: readers will get confused, until it is explained. But that's ok. And as long as you don't mention 5 years and snu snu in the same sentence, and it is after the explanation, you should be fine.

Not done the math but you could investigate having a binary planet (or planet as moon of a gas giant) and the fluctuations in the orbit from that could cause seasons. Getting the timing right while keeping sizes and positionings reasonable is not trivial though.

@S.R.Martin I'd go one step further. Just don't use years. Call them "cycles" or whatever. "How old are you?", "5 Cycles" reduces the possibility of confusion greatly.

Could you please clarify which planet is the "second" in your diagram? It appears you have a binary pair with two bodies (presumably planets) co-orbital with the second one. Maybe just tell us the name - is it Hirr, Harr, or Hilor?

Yeah, I realize that my diagram is not the clearest one. The second planet is "Harr".

If solving the issue of the reader's interpretation is the most important, you could always use Tolkien's technique of saying it's translated and converted from the original language and units. Tolkien even re-translated Frodo from Maura

Have them divide the year into seven seasons -- four is not set in stone even on earth -- and then count their ages and other such things in seasons.

@jamesqf Ancient civilizations always used astronomical observations (including the position of the sun) to track time. Seasons were observed to track closely with the passage of time, but were not themselves the basis for time keeping. (IIRC, the Egyptians used the position of Sirius as a means for determining when to expect the Nile to begin flooding, rather than basing their calendar on something like flooding that didn't repeat with high precision.)

@chepner: Sure, because the Earth year is, in many places, strongly correlated with seasonal events, like the Nile flooding. It's also a fairly convenient length for measuring human events, like people's ages. (But not so useful for dogs :-() People also use the moon's period for measuring time, but we don't often use (or even notice) things like precession of equinoxes or Milankovitch cycles. So I'm suggesting that the OP look at what people who live in places without notable seasonal changes do.

I think you're fussing too much. Fans of SF&F are ready for quirks and oddities in alien worlds and you're giving them too little credit. Once you explain in the story the length of a year, only the newest of readers will flounder. SUGGESTION: start with a "Bilbo Baggins Birthday Party" where everyone is celebrating an elder's 15th birthday. Throw in some classic birthday cliches "Well, grandad, when you were my age, did you even think you'd reach 15?" snort "When I was four years old, I had other things to think about." Wink at some young ladies in old codger fashion.

Adding onto @jamesqf: When I asked for advice on a similar issue, I was told: "Planets don't have seasons. Areas of planets do." And I recently read about someplace in real life where they consider the period from around September to March to be three seasons (or something like that). There's a rainy season, etc.

Knowing little about astronomy, would it be possible for the axial tilt itself to rotate very slowly, at about (6.78/2=) 3.39 cycles per rotation around the sun? Then spring/summer/winter/fall would match earth...ish? Maybe? I speculate the concept makes no sense, and objects can't rotate that way.

@Shawn V. Wilson: Yes, India (or most of it), where you have a hot, dry summer (March-May), the rainy monsoon (June-October), and a cool, dry winter (November-February). Then you have Mediterranean climates (like much of California), that really just have summer and winter.

I don't think you give your audience enough credit. ST:Voyager had an adult aged 3 (Kes).

@Mary post that as an answer if you haven't already, it's a good one.

I'm reminded of 2 things... 1: "Podkayne of Mars" where a 16 year old girl calls herself 8 years old - because Mars. Later, she travels to Venus and, when she gets there, describes herself as 32 years old. 2: The "Helliconia" series. The planet orbits a first sun, in a fairly cold orbit. The second sun of the binary system is in a highly elliptical orbit - it's effects create a 1,000 year cycle. You could approximate an Earth year with one sun, and have 7-year climate variations similar to Earths 11-year solar flare cycle.

Are changing seasons a necessary part of the story? Are you simply trying to have a set reference for time within the context of the story? Depending on the case, I can think of a few non-stellar, planetary mechanisms for seasonal change.

The seasons aren't really important. They're fairly unpronounced as is already, with the whole planet being somewhere closer to the end of Jurassic's climate.