Bob loves plants. More specifically, he loves terrariums.

Bob's magnum opus is a large terrarium made from a 5-gallon glass water jug. Inside is a miniature ecosystem: plants grow, detritivores feed on the fallen leaves, larger insects hunt them down, and anything that dies has its constituent nutrients recycled to propagate more life. Nothing enters or leaves the jug, not even air. For our intents and purposes it is the perfect self-sustaining terrarium.

One day Bob wakes up and learns that nuclear war will come in exactly 24 hours. Let's handwave how or why: all that matters is that the 100 most populated US cities will be hit with 10 nukes each, including his home in San Francisco.

Bob is scared for his life. But more importantly, Bob is scared for his terrarium. He mustn't let it die, no matter what.

Lets say Bob has a million dollars to spend and the determination to do whatever it takes to keep his plants alive for at least 1 year. As stated the ecosystem is self-sustaining, but even it has some needs. Bob will have to:

  • establish a light source- natural sunlight from a window is a possibility, but he cannot rely on that during a nuclear winter. The ideal alternative is a typical warm white light bulb, which will require power lasting at least the whole year.
  • Keep it safe from radiation- I couldn't find much on how much radiation glass or plants can take, so let's just say to keep it as far away from major cities as possible while still fulfilling the first requirement.

Given the above, and that Bob cannot leave the United States for any reason: what is the best thing Bob can do to make sure his terrarium survives a nuclear war? It does not matter whether he lives or dies.

  • $\begingroup$ Do you have a good source on the self sustaining terrarium? 20 gallons seems awfully small to me to have a complete ecosystem, especially with something as large and complicated as insects. $\endgroup$
    – quarague
    Commented Apr 30, 2022 at 15:43
  • $\begingroup$ @quarague sciencenatures.com/2021/09/… $\endgroup$ Commented Apr 30, 2022 at 16:28
  • 1
    $\begingroup$ @SurpriseDog That works better than I expected but this one only contains a plant and bacteria no insects. And as far as I can see this also only works for the life time of this one individual plant (which is easily long enough for OPs question). $\endgroup$
    – quarague
    Commented Apr 30, 2022 at 17:18
  • 1
    $\begingroup$ The budget should be zero, otherwise: "For sale: Kansas missile silo, $380,000" $\endgroup$
    – Mazura
    Commented May 1, 2022 at 4:01
  • $\begingroup$ @quarague the YouTube channel Life in Jars? is all about a guy making ecospheres that self sustain for many months, with small animals. These ecospheres are only about a pint, maybe a gallon max. Ecospheres are pretty comparable to terrariums biologically - small terrariums are possible and common. $\endgroup$
    – Drake P
    Commented May 1, 2022 at 12:50

4 Answers 4


This might be a boring answer, but the terrarium doesn't make a huge difference. Bob should do what anyone else who had $1 million and knew about an upcoming nuclear war should do.

Bob should spend \$800k on non perishable food, medical supplies, gasoline, a geiger counter, and a grow light with a bunch of spare bulbs, then move to a rural community; use the remaining $200k on a house with a decent basement, and a generator. Bob should make good friends with his neighbors, working together is best for everyone. If his community is healthy and safe, he should be able to take care of his terrarium in his free time.

  • 4
    $\begingroup$ Good answer, but that's a lot to do in 24 hours! $\endgroup$
    – elemtilas
    Commented Apr 30, 2022 at 14:09
  • $\begingroup$ At the beginning, I was disappointed (this answer doesn't even think of trying to make the terrarium work). The end is a sweet twist. Wish I could upvote answers like this eleven times. $\endgroup$
    – Nuclear241
    Commented Apr 30, 2022 at 16:20
  • 1
    $\begingroup$ @elemtilas if Bob really cared about his terrarium, he'd move to a rural community even before learning about the upcoming war. There are a lot more problems that could kill the terrarium in the city even during peace-time. His apartment could be broken into, one of the other tenants could have a fire, etc. $\endgroup$
    – Ryan_L
    Commented May 1, 2022 at 15:27
  • $\begingroup$ With only a 24 warning, would it be sufficient to 1-Buy the food, and 2-Get it where it needs to be? I suspect that an 800k sale isn't going to go unnoticed, and might not be ready in time or get delayed for inspections, especially on such short notice. $\endgroup$
    – vinzzz001
    Commented May 4, 2022 at 9:16

Buy a 50 W LED grow light. Buy about two tons of lithium batteries (assuming 200 W*h/kg). Charge them. Buy or rent a large bank vault -- 12" to 18" thick walls are standard, and will stop pretty much any radiation if they stay intact. Choose one in a location that's unlikely to get a direct hit, and hope you don't have an earthquake within the year. Put the batteries, LED, and carboy in the vault. Lock the door. Come back in a year.

  • $\begingroup$ You will also need to regulate temperature in the vault or at least in the terrarium. That will require additional energy. $\endgroup$
    – jwdonahue
    Commented Apr 30, 2022 at 22:47
  • 2
    $\begingroup$ "You will also need to regulate temperature in the vault or at least in the terrarium." You likely won't, though, in the special case of an underground vault in san francisco. Soil temperature is extremely hospitable year round, and the thermal mass is likely high enough that neither the 50 watts you're adding nor the nuclear winter outside will change much within a year. $\endgroup$
    – addaon
    Commented Apr 30, 2022 at 22:59
  • $\begingroup$ Li-Ion batteries drain by themselves. You may want Acid batteries, which are known to have better long time storage ability $\endgroup$
    – Trish
    Commented May 4, 2022 at 6:17

The small town approach won't work--your small town is going to get overrun by the survivors from the cities looking for food.

The basic approach is right, though--but you're looking for a 4x4 HCV, not a house. Head into the most remote location you can reach, something without too good visibility so people don't see your vehicle.

  • $\begingroup$ You won't be able to bring a lot of food with you in a vehicle. Not to mention, you will need fuel to keep the car running and keep yourself/the terrarium warm. In even a medium-size basement there is way more room for food and water. And a house can be very well insulated, reducing the fuel needed to warm it. $\endgroup$
    – vinzzz001
    Commented May 4, 2022 at 9:28
  • $\begingroup$ @vinzzz001 You can make multiple trips hauling supplies. The problem with houses is that people will find it and take your food. $\endgroup$ Commented May 5, 2022 at 1:56

Of course Bob's plants can survive, in any built world.

If Bob cared about natural sunlight being unreliable, why would you not let him use a generator for that typical warm, white light bulb?

If he cared about radiation, why would you not let him use radiation-resistant glass?


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