Growth of cultures in the mosscubator has been painfully slow. The cause seems to be fast desiccation: Despite a humidifier constantly maintaining a humidity of 75-80%, I noticed that the mosses in my mosscubator were bone dry mere hours after the daily watering. I suspect the combination of high air speeds caused by the ventilator and the fridge constantly condensing water vapor acted as a drying apparatus. The solution is obvious: Keep the moisture close to the mosses. In other words, they need a closed culture vessel. The petri dishes I use come with a lid; the problem is their insufficient height. I didn’t want to switch back to glass jars, manipulating the cultures in them is difficult and the lids are not transparent. In general, I didn’t want to buy any kind of vessel, because they are expensive and usually don’t have the size I want or need. The idea was to make boxes from some kind of transparent foil. I settled on viewfoil: Its transparent, chemically resistant and has just the right thickness to yield sturdy boxes. Also, its not expensive.

Making the boxes isn’t difficult, everyone who had some arts and crafts in kindergarten and school should know how to make them. I just draft the outlines on the viewfoil, cut it out, crease all edges, then glue everything together using transparent double-sided tape. The only important things to remember are to make the lid a bit larger and to taper the flaps, else the box wont fit together properly. As you can see on the pictures, my standard size is 10cm x 10cm x 5cm, but I also use smaller and larger ones. To speed up drafting I put marks on my ruler.

As a substrate I decided to cover the clay pellets with about half a centimetre of standard garden soil. Without peat of course, since its production destroys bogs, which are very endangered ecosystems. The moss is then transferred to the new vessel, often dead material is removed in the process. This is just to stop mosses from growing into the pores of the pelets and to cover up its ugly colour.

The results are very encouraging. The cultures stay moist much longer, some for several days. They also now show a healthy vibrant green colour nearly constantly. In case of Polytrichum I noticed a surprising acceleration of growth. I still need to transfer three or four cultures from petri dishes to the new boxes, but I think they will be in use for the foreseeable future. In the two months they were in use I haven’t noticed any rot or moulds on the boxes or in the cultures. As an extra, the humidifier is no longer needed cutting down on power consumption and water use. All in all im very happy with this new solution.