Preparing coffeetree seeds for planting

Two years ago David over at True Blue Sam sent me a large batch of coffeetree seeds and I've had a 20% survival rate after two dry years and I'm cautiously optimistic after this winter. I found a local source and was able to get 177 seeds for this year's planting.

Known as scarification, my method of preparing Kentucky coffeetree seeds for planting is simply to scratch my way through the hard shell of the seedcoat to get to the meat of the seed. About the size and coloration of the popular candy, Milk Dud, I would not recommend playing a trick on your friends by throwing a couple of seeds in the box.

My original method of scaring the seed was to use a triangular file and spending 15+ minutes filing to breach the seedcoat. I switched to an oscillating cutting saw and could prep a seed less than a minute but this made me a bit nervous having a vibrating blade near my fingers. One slip and I'd never play the violin again.

I picked up a Dremel 8100 tool this past weekend for this specific purpose. Except for the limitations of the original cutting wheel (it's not designed for cutting plant fiber and would gum up), I'm pleased with the results so far. This particular model holds a charge for about 15 seeds, or 30 minutes, and I think I will get better results with a different cutting blade and I ordered one.

Some cautionary pre-instructions:

1. Do this in a well ventilated area and you may need to wear a mask. The dust can be an irritant and the cutting wheel can end up "burning" the seedcoat which irritates the eyes as well.
2. Do not hold the seed with your hands. Common sense
3. Make small cuts and go slow.
4. Wear eye protection. Chips from the seedcoat can fly up into your face.

I use this ratcheting clamp to hold the seed: 

Use the cutting blade to cut the seedcoat, make small cuts and stop when you reach the yellow "meat" of the seed.

I've had more success when I cut about 90% to 100% around the seed, but I'm experimenting the results of cutting about 50%.

It's not the neatest cut, but does the job. One interesting note is that sparks can fly using the cutting tool blade.

Others recommend soaking the seeds in water for 24 hours after scaring but I plant the seed right away, either in the ground or potted. The moisture in the soil will soften the seedcoat in less that a day. I planted these seeds near the surface in pots and the previous best results is to keep the soil moist but not too wet, otherwise the seed will soften and rot. In about two weeks, the taproot will start to form.

I'm conducting tests this year as I can afford to with this many seeds. I bagged up some in wet peat moss and will plant them at the tree farm after germination. This worked well with the acorns, so why not? I soaked some in acid to see if this would be an alternative to using electric tools. I'm working on a couple of other ideas including the cut direction, temperature and seed planting depth. There's not much information out there as the coffeetree is not a popular tree in the public's mind.

I'll report our progress and share the best method that works for us.