For extended details see publication:
Mora A, Rollo A, Molina RA, Mora C (2023) The SheetPot: a new pot that overcomes several shortcomings of seedling production
This pot system is part of the developments of the Carbon Neutrality project. A citizen-science initiative, in which individuals calculate their carbon footprint, the number of trees needed to offset those emissions and then plant the trees. We have managed to plant up to 10,000 trees in two hours by 2,000 volunteers.
However, due to the lack of maintenance after planting, we relay in the use of healthy seedlings to maximize survival after planting.
"Healthy" characteristics include seedlings with no root bounding, tall enough to escape above-ground competition with weeds, deep roots to gain fast access to the water table and avoid below-ground weed root competition, while grown in a pot system from which seedlings can be easily removed to reduce planting shock.
While many types of pots are commercially available, commonly they do not satisfy all the criteria above, and if they do, they are often not cheap. Here we describe a set of pot prototypes that achieve the criteria above while being affordable.
Our first version of the pot system was made out of paper, and the internet is full of DYI examples.
The idea here is that seedlings can be grown in a paper pot, and put directly in the ground avoiding problems of planting shock as the seedling is plated directly with the paper pot. We contacted numerous suppliers in the USA and China, and used numerous materials and types of coatings.
Here is the assembling of it:
This pot system was a nightmare. The paper suffered from decomposition, and while some papers lasted longer, they rarely exceed two months. The paper decomposing fast caused the soil to erode exposing the root system and causing a major stress to the seedling evidenced by the fact that they rarely grew; also, the pots stuck to each other when on contact at the nursery
We developed a tray with the expectation that keeping the pots separated could elongate the duration of the paper pot, while avoiding contacts that caused them to stick with each other. As expected the tray avoided any contact between pots, but the paper still decomposed fast.
We then move to non-woven bags, and we found several Chinese manufactures that made the bags at 3cent per bags... seedlings really loved these bags.
There were, however, two major problems: the bags were difficult to fill and the roots crossed from bag to bag when in contact. For the second problem, we created a tray, and it worked pretty well.
However, overcoming problem one was more difficult. We try numerous filling mechanisms, but they were still hard to implement. Filling these bags was very labor intensive and slow.
Then, the idea occurred to us of using nets as pots...the idea here is that one can create a roll with the net, creating a cylinder that can be used as pot. This overcomes the problem of filling as the net generates a cylinder that can stand by itself. We used the tray developed above to hold the rolls. At first, we used chicken plastic fencing
This mesh pots worked well, in the sense that they kept the shape, but soil eroded as the holes were too large. So, we used mosquito nets, instead.
They really worked like a charm: soil did not erode, there was full on oxygenation, not water perch, the seedling could be easily removed by simply unrolling the net, they were re-usable forever, very cheap to transports and we even found a Chinese manufacturer to make them; price $30 cents per unit.
Here is the assembling of it:
It looked like we have our winner. But not quite. We needed a try. We developed a try that was affordable in price per unit ($3 dollars) holding 9 seedlings and with UV protection, we expected it to last several years. The problem we had with our tray was that it was too bulky which made the cost of shipping very expensive. Unfortunately, we realized this problem only when planning mass production.
At this stage, the tray was fulfilling three basic functions: 1) keeping seedlings spaced, 2) keeping the shape of the net rolls, and 3) facilitating transportation of the seedlings. In reality of all these functions only function 2 required for the tray to be tall. So, we figure out a way to move that function to the pot, and make a smaller tray. Introducing our Mora's Pot:
As shown below, Mora's Pot is a plastic sheet, that can be rolled and locked in place.
Here is the assembling of it:
Here is the filling of it:
Already filled:
A full version:
Holes on the sheet can be configurated in many forms and patterns to affect oxygen exchange, irrigation, water logging, drying, etc. We recommend to use UV protection to maximize the life usage of the sheets. While we used 0.5mm thick sheets, we have noted that they can be just as good with much thinner materials, even as thin as a paper sheet (100 microns), which will reduce cost for manufacturing and shipping considerably.
Once the design was tested in the lab, we searched numerous manufacturers, of which those located in China provided the best deals. The mold cost $200 (a one-time cost), and each sheet of 5 mm thickness cost $0.30 cents. The price per sheet can be reduced by more than half with thinner materials, which have not been tested.
Our die cut was manufactured by JinJiang Jiaxing Group Co.,Limited (contact person Tony : sales37@jiaxing-groups.com and service18@jiaxing-groups.com). You are welcome to contact them directly and ask to use our mold.
The file needed by the manufacturer is called: MorasPot in this repository. We provided it in different file formats, but the PDF will satisfy in most cases.
For future, versions, we recommend trying a thinner material, ensure very well that the manufacturer adds UV material, that the holes are clear (the die-cut should remove completely at least the holes for the locking mechanism). And try, alternative, simpler locking mechanisms, even the use of no locking mechanisms at all.
Alternative usage without the locking mechanism:
