If we humans are serious about terraforming our famous neighbor, Mars, then the terraforming process would take thousands of years before it becomes habitable enough for humans to live in. But that is only the beginning...

Turns out that there are many, many, MANY problems we should take into consideration while terraforming Mars, but for the sake of this question, let's narrow it down to one problem--its 687-day revolution. As I have discovered in this question, the longer a year is, the harder it will be for any Earth-based lifeforms to live in. So when Earth-based terraformers have a collection of pioneering species of plants (doesn't matter which--herb, shrub, vine, tree, vascular, nonvascular) and insects (their relationship with plants runs really deep), how will they, who are used to a 365-day year, adapt to live under Mars's longer year?

Oh, and before you bring up genetic engineering, don't. That would be cheating, and cheating is just plain lazy.

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    $\begingroup$ What makes genetic engineering "cheating"? $\endgroup$
    – Tim B
    Sep 5, 2019 at 23:14
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    $\begingroup$ Most plants won't even notice, the change in their physiology is triggered by changes in the environment, not some invisible clock. $\endgroup$
    – John
    Sep 5, 2019 at 23:21
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    $\begingroup$ Well, they will obviously bring some or many plants and insects to the New New World, and see which of them die and which survive and multiply. And those which survive and multiply will be the ancestors of the plants and insects of the New New World. $\endgroup$
    – AlexP
    Sep 5, 2019 at 23:34
  • $\begingroup$ If it's terraformed there's no problem, other than concerns over extended cold spells any worries over extended seasons are groundless & there are plenty of arctic & similar plants & insects that can remain frozen seemingly indefinitely so een that seems a silly concern. $\endgroup$
    – Pelinore
    Sep 6, 2019 at 0:14
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    $\begingroup$ Adaptation to a new environment will go via genetic changes. $\endgroup$
    – L.Dutch
    Sep 6, 2019 at 3:56

1 Answer 1


The real problem with extending the seasons on Earth isn't that the plants can't cope per se; as has been mentioned by John in comments, plants on earth are already designed to react to their environment. When spring comes early, plants sense the change and start to bud. If winter is longer, then they just stay dormant that bit longer until they sense the changes in the environment that essentially 'activate them'. As such, you don't need any significant change to most plants to get them to support a longer cycle.

That said, a longer cycle isn't completely free of complications for your plants. Staying dormant during the winter cycle for longer increases the risk that the internal nutrients of the plant won't hold out long enough, and a more active cycle during the summer means that it's taking more nutrients and water out of the ground for a longer period and the soil and its nutrient and water base may not be able to support that for the extended period without some form of cropping - regular fertilisation and watering on the part of someone specifically there to care for the plants.

Of course, we're also assuming that the extended calendar is the only consideration here. Naturally, if Mars is significantly colder than Earth even after a substantial terraforming effort, then the plants might 'think' it's still winter, even in the depths of its summer period. While out of scope of the actual question, this is an important consideration as the plant will get about half the sunlight that it gets on earth at Mars, and if the temperature is still cold then it's a fallacy to think that the plant will react to a 'relative' cycle of hot and cold.

Ultimately though, there is a place on earth that doesn't really experience significant temperature variations, doesn't really have a summer and winter cycle and yet in which plants thrive;

The equator.

Think about it; During both winter and summer, the equator is exactly the same angle from the sun. If anything, spring and autumn are going to be slightly hotter than both summer and winter because they are the point of transition, and therefore the equinox at noon is the one time when any point on the equator is actually in full sun. But, for all practical purposes, the differentiation between the two seasons we regularly think of as the most extreme is least in equatorial regions.

As such, there are a lot of plants in that area that are not deciduous. There's no point for a plant in that region adapting to a cold / hot cycle. I'd argue that if you're going to put plants on Mars, and you can keep them warm, the plants from this region are the first to try out.

Mars will have the same dynamics at its equator, meaning that the only variation you need to think about is in fact keeping the plants at a surviveable temperature. This would be the first place to start and then you can worry about the planetary seasonal cycle after you have plants surviving on Mars without it. Don't unnecessarily complicate your terraforming efforts as there are far more important considerations to think about in getting plants to grow there than seasons. So take them out of the equation (no pun intended) first and focus your plantings on Mars' equator.

Doing that will in point of fact will serve as a great control for the experiment of getting plants to grow and take a variable out of the mix that could otherwise muddy the waters.

  • $\begingroup$ "a more active cycle during the summer means that it's taking more nutrients and water out of the ground for a longer period and the soil and its nutrient and water base may not be able to support that for the extended period" So you'v never heard of tropical rainforests then? suggest you think again on that bit ;) $\endgroup$
    – Pelinore
    Sep 6, 2019 at 0:09
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    $\begingroup$ @Pelinore well yes I have, which is precisely why I describe equatorial regions. I'm just pointing out that in deciduous plants, their active cycle requires a very fertile soil and regular water supply, both of which tropical rainforests have in abundance. Mars on the other hand has neither, which was the primary point I was trying to make. $\endgroup$
    – Tim B II
    Sep 6, 2019 at 0:13
  • $\begingroup$ & I'm just pointing out that all growing plants drop leaves etc that returns nutrients to the ground (the very source of that thing 'tropical rainforests have in abundance'), a longer growing season is never a problem in a mixed ecology, you appear to have confused yourself with single crop agricultural issues, just saying :) $\endgroup$
    – Pelinore
    Sep 6, 2019 at 0:18
  • $\begingroup$ @Pelinore "longer growing season is never a problem in a mixed ecology' this is simply incorrect and a very narrow perspective of things. tropical rainforests are an exception by very definition of the fact that they are tropical and therefore have ample water and plants adapted to that environment. I'm curious; have you ever seen Australian bushland after a long summer? Californian woodland? Ever seen what it looks like when a fire rips through it and the years it takes to recover? I just think that your one example is an exception to what I'm saying, not the norm. $\endgroup$
    – Tim B II
    Sep 6, 2019 at 0:48
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    $\begingroup$ WRT sunlight, remember that the amount of sunlight falling on a given area (watts per sq meter) depends on the angle of incidence. Thus plants growing near the Martian equator would recieve about the same amount of solar energy as Earth plants growing around 60 degrees. So Arctic vegetation should do ok from a solar energy standpoint, Also many temperate & tropical plants grow in shade or part sun... $\endgroup$
    – jamesqf
    Sep 6, 2019 at 5:40

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