Ok. So any generational ship is going to need to dedicate a lot of space to growing food. Assuming the ship has limited area under gravity (in the case of the NEP ships, only the habitation modules have significant spin gravity) that means that the plants will have to grow in zero G. That’s ok. We have learnt that plants can grow in zero G without too much complications. However one of the complications of growing plants in zero G is germination. Under gravity, plants are able to orientate themselves to grow leaves up and roots down. In zero G this doesn’t really happen and they grow mainly based on the original orientation of the seed.
So to solve this issue, you can manually orientate each seed so they grow in the right direction, which sounds incredibly labour intensive. Or you could just germinate all the seeds under gravity.
Some quick research and math tells me that most vegetables take about 20% of their growing time, from seed to harvest, in germination. So at any given time we need 20% of our plants under gravity. Luckily seeds don’t need much space to germinate compared to growing for harvest yield. Let’s say they need 1/4th the area per plant in the germination stage. This gives us a total of 5% our crop area needing to be under gravity for germination. This number only gets lower once you account for perennial plants. So this 5% needs to be located either in the habitation modules or in centrifuges. With the plants needing to be moved from germination areas to growing areas once germination is done.
