2-direction Planter Boxes for Space Agriculture

In order to more effectively use available growing space in microgravity, I designed and built a grow-box that placed two plants at opposite ends. The plants' bases are placed on opposite ends of the grow box with the light source in between the two, as show in Figure 1. That way, while the plants are young, there's room above them for the other young plant, but as they mature, they make their way towards the other side, while leaving room for the opposite plant near its base, as show in Figure 2.

With this design in mind, I built a prototype that would satisfy light, nutrient, and water needs of the plants.

Supplies

Container: For my prototype I used a cardboard shoe box at 15"x10"x6", lid included. The important feature is that you can cut holes out of the material.
2 Planters: This is where the seeds are planed. They need to fit width-wise into the container and still leave plenty of room length-wise. I use an aluminum can and plastic water bottle.
Water reservoir: Fits inside the box between the two planters.
Wick: This is to transport water from the reservoir to the dirt as it dries. I used 12" strands of cotton yarn for each planter.
Light source: I used a regular and UV flashlights. Plants photosynthesize from red and blue light, but I added the UV light anyway to more closely mimic real light.
Aluminum Foil: Enough to cover the surface of the container's vertical walls. This was done to conserve heat and light energy, since the room I kept the box in was cold.
Dirt/ growth substrate: I used old-fashioned dirt, since I the nutritional value would've been better than anything I could've added artificially.
Seeds: I planted cabbage and arugula seeds.
Paper clip/ quilting needle (optional): This makes it easier to get the wick in the planters.

Step 1: Step 1: Prepare the Container.

Prepare the container. The dimensions must be within a 50cm/19.6" cube. To conserve light and heat I lined the vertical walls with aluminum foil. Then I cut out holes for my light source, halfway across the length of box, tangential to the bottom, so the flashlights could rest on the ground, and the circumference matching the outside rim of my flashlights.

I put the flashlights outside the box because I didn't want any barriers to the plant growth or blockage of light.

Step 2: Step 2: Prepare the Planters

First I cut slits for the plants to grow out of. I made them 0.5" thick and running lengthwise across my bottles leaving only an inch at the top and bottom.
Then I unscrewed the lid/ took the can cap off, and filled it with dirt. To make this process easier, I made a funnel out of paper that I scooped dirt into.
Next, I added the blue yarn to be used as a wick. Wicks are an ancient technology that makes use of capillary action, transporting moisture from an area of high concentration (the water reservoir) to an area of lower concentration (the dirt). Because I didn't want to cut myself on the aluminum can's edges, I tied one end of the yarn to the bend of a paperclip, unfolded the rest, and used the end to thread the yarn through the opening of the planters and into the dirt. Then I cut the string from the paperclip.

Step 3: Step 3: Plant the Seeds

I inserted the cabbage and arugula seeds through the slit I cut out in step 2. Follow the instructions on the seed package with regards to depth and spacing.

Step 4: Step 4: Assemble the Grow Box

The planters go on opposite ends, the reservoir goes in-between, long enough for the wicks to reach, the lid goes on top, the light source sits outside the box with the light entering through the holes. I put the whole thing under my bed.

Step 5: Step 5: Allow the Plants to Grow

I checked up on the grow box every day, topping off the water reservoirs when needed, turning on the flashlights each morning and of in the evening (plants need a dark period), and replacing the batteries of the flashlights when they dim.

I planted arugula in the water bottle and the cabbage in the Arizona Tea; the arugula made some significant growth in the three weeks, but I only saw one shoot coming out of the cabbage can.