4 However, there are challenges with growing plants in space. Due to the lack of gravity in space, the oxygen that the plants produce stays around the plants. This can actually kill them, so fans are needed to circulate the air. Without gravity, roots don’t “know” to grow down, leaves don’t know to grow up, and water doesn’t easily travel up the roots to the leaves. Specialized containers are being developed to help the plants grow correctly. There are challenges with soil as well. As soil is too heavy to send to space, special liquid gels are used to sustain plant growth. These retain water and deliver it to the plants.