Some seed types form a very hard shell around the inner embryo that actually germinates. This occurs either naturally or when seeds get old. Even very old seeds can sometimes still germinate if the water can get inside. In order to do this scarification is required.
The purpose of doing this is to soften the outer shell of the seed so that the new sprout has a chance to break through the shell and germinate.
Scarification simply means scratching, weakening or creating slices or notches in the hard outer shell. This can be done either manually or by chemical means. I’ll outline four different methods of doing this, using vinegar, boiling water, sandpaper and the knife.
Supplies required: Vinegar, paring knife, a drinking glass, emery board or fine sandpaper, boiling water
The Knife Method
This one is best to do with larger seeds. Carefully use the paring knife to cut a tiny nick in the side of each seed. Wash the seeds and sow them as the instructions say on the package for that particular seed.
Put the seeds in the drinking glass and add vinegar just to cover the seeds. Stir and let stand for about ten minutes. Then wash the seeds with clean water and sow them as instructed on the package. If you have a UV light or a grow table in your house then that will be the best place to put them to help the seeds come to life.
Boiling Water Method
This method is simple. Bring a small pot of water to a boil. Add the seeds so that they are all submerged and stir, then leave the seeds there until the water completely cools off. Rinse the seeds, then plant them either outside if it’s appropriate or in planting medium inside under a UV light.
Sandpaper or Emery Board Method
Use the emery board or sandpaper back and forth over the surface of the seeds. If the seeds are large then you can hold the seed and scratch that back and forth but if the seeds are small then use two pieces of sandpaper on them.
The image here is the boiling water method in action. I have about 6 floating seeds out of the approximately 20 seeds in the pot. I think the ones that are floating are probably dead. The seeds you see here are well in excess of ten years old, possibly closer to 15. It’ll be interesting to see if any of them sprout. I’ll update as time does along and let you know how it goes!
Update…the seeds shown here didn’t sprout. They were very,very old and my hopes weren’t high because of their age. We’ll try again next year with some fresh seeds.
Good luck! Let me know if any of these methods worked for you.