I designed and produced a pair of pliers to help pick up and transfer small seedlings with minimal disturbance. The pliers work by picking up soil around the plant and lifting that rather than the actual plant.
The pliers are 3d printed. I created the design using OpenSCAD. They are designed to be printer with 100% infill, and the top section needs to be printed with support to elevate the hinge area. It is held together with a 16mm M4 screw, couple washers and a lock nut.
I had planted some seeds in some plastic take away containers. The soil was only about 15mm deep. I noticed that only a few days after breaking the surface the tiny plants already had roots that where wandering around and likely to get tangled. I realised I needed to give them more space and separate growing areas quickly.
Some seedlings had surprisingly long roots. The 2 cm tall plants had to up to 8cm long roots. The new seedlings in the shallow soil had much longer roots compared to the older plants in the deeper soil. It may be influenced by the amount of moisture stored in the deeper soil which would have been much greater than the shallow soil.
I attempted to create extra holes in the destination soil and feed long roots down further. A few plants I damaged. As I was pulling plants up I felt their roots catch and snap as I lifted them too quickly.
After being moved seedlings wilted a little. I suspect the damaged one’s wilted more. Watering helped a little except for the two largest plants which took much longer to recover.
The pliers where a mixed success. Sometimes it was difficult to get a good enough grasp to lift the plant, dragging soil over the tiny leaves. The grip tips of the pliers needed to be sharpened to get into the soil easily. I filed them down after printing but this would be easy to fix in the 3d model. After this I was concerned that I might accidentally sever some roots while pushing the pliers into the soil, or roots might get pinched as the grip tips close. It was hard to tell if any damage was caused this way.
The plants where spaced closely and using the pliers was a tight squeeze, but I am happy with the final size. Any bigger and it would be more difficult to avoid disturbing other plants when using them. Too small and it wouldn’t grab enough soil around the plant to pick up.
Even after some root damage and wilting all of the seedlings seem to have recovered except for one which was much older. I suspect the older plants suffered more root damage and disturbance.
I am happy with pliers as far as working like a hand tool. They feel like scissors, they are smooth, and hold together securely enough. @csirac2_ commented “I assumed they were something you bought from Bunnings”.
Next time I will plant trays with one fewer column and one fewer row in the starting tray. This will allow a little more space between plants to work. I will also make a guide so I can better centre each seed in its allocated cell. This will make identifying what cell a plant is in later easier.
Based on plant size and minimising disturbance I think that the best time to move the seedlings is as soon as they break the surface and become visible. That way you can more easily grab the whole plant and sounding soil and there is less plant to damage.
Adding rounded teeth with spaces to the edges and bottom of the grip tips may also help. It could give long roots space to avoid being pinched and may make it easier to work into the soil. Also changing the grip tips from a circle to an ellipse may help grab the soil better.
