Richters Free Lecture Series
SUCCESS WITH SEEDING
Hard to Germinate Seeds
Some seeds may be difficult to germinate because they have a very hard seed coat. Water cannot get into the seed and the embryo cannot break out of the seed. Scarification or scratching may be necessary to weaken or puncture the seed coat. This homemade grinder is one way we are able to scarify a fairly large amount of seed.
The bottom surface of the grinder is covered with sandpaper as is the upper disk with the handle.
With seeds placed between the two layers of sandpaper, the seed coats are scratched enough to allow water to diffuse in and allow the embryo to develop normally. It is important not to grind too much otherwise the living embryo inside will be damaged.
Some seeds require other treatments to break dormancy. Many of these require a cold treatment to wake them up. Often a drastic change from cold to warm is enough to get the seeds going. Seed the box, pot, or flat as you normally would, water it, enclose in a plastic bag, and then place in the fridge. I usually leave the seed box in the fridge for 4 to 8 weeks, and then take it out and put it somewhere warm.
Sometimes you have to keep alternating the cold-warm treatment until germination begins. For example, siberian ginseng needs at least two cycles of cold-warm treatment before it will germinate.
Sometimes it is best just to put the seed flat outside covered with a mulch for the winter. Sweet cicely is a good example.