Some seeds have especially thick or hard outer coatings surrounding them. To facilitate germination of these seeds, a gardener must scarify the seeds prior to planting them. Scarification is a treatment that either breaks or reduces the outer coating. The most widely used methods of scarification are water soaking, acid treatment and abrasion with sandpaper. Using any of these scarification methods helps the seed germinate through the hard outer coating.
Rub seeds with the sandpaper as long as they are large enough for you to hold the seeds and see the progress of the scarification as you rub with the sandpaper. Some seeds are not large enough to make this possible. Rub the seeds until the outer coating is dull. Do not rub to the point where the seeds are pitted or cracked, however, because this may destroy the embryo.
Heat water to a temperature between 170 and 210 degrees F. Allow the water to cool down to approximately 150 degrees F. Place the seeds into the glass jar and pour the cooled water over the seeds. Use twice as much water as seeds in the jar. Allow the seeds to soak for 24 hours and then plant them.
Scarify the seeds with cider vinegar. Combine ½ cup cider vinegar with 2 cups of warm water. Use twice as much cider vinegar solution as seeds. Place the seeds in the glass jar and pour the vinegar solution over the seeds. Allow the seeds to soak for approximately 12 hours, rinse them and then plant them.