Gardening and Forestry: Improving Seed Germination by Scarification

When you plant something, you expect it to come up. Perhaps you hunger for beefsteak tomatoes, cucumbers, lettuce, spinach, eggplants, squash and other garden vegetables. Then again, you may be an herbalist looking forward to a crop that will flavor your vegetable and meat dishes with an aromatic delicacy unachievable if you purchased store-bought substitutes. Or, you may be a forester who wishes to assure that the plant seeds you put into the ground will come up!

The Problem and a Solution

There are some varieties of vegetation that produce seeds which have a thick or otherwise nearly impenetrable coat that hampers the growth process. What can be done to assure a high germination percentage for such seeds? One can employ a process called scarification. The website called The Gardener's Resource defines scarification as, "The physical or chemical treatment given to some seeds in order to weaken the seed coat sufficiently for germination to occur."

Scarification can be either a mechanical process such as sanding or cutting the outer seed coat, or it can involve a chemical process that is strong enough to etch (thin) or weaken the coat, but that is not strong enough to eat into the kernel of the seed. Appropriate scarification merely modifies the outer seed coat so it is easier for the seed to grow.

Seeds difficult to germinate may improve if you drill a small hole into their outer coat, and then you immerse them in water for one or more days. As an alternative, the coat may be sanded to thin it. Or, perhaps instead, you will use a file to expose the underlying kernel. One source even suggests that seeds and sand can be pulse-blended a few cycles to thin the seed coat. Finally, oddly enough, some seeds germinate better if they have been exposed to fire!

Another Method of Scarification - Chemistry!

Did you enjoy chemistry in high school? If so, then the "chemical method" may be the choice for you. The chemical method of scarification generally involves the use of sulfuric acid, although another mineral acid - hydrochloric acid - sometimes is used instead. Actually, hydrochloric acid is nature's own chemical method of scarification. Seeds eaten by birds or other animals enter the digestive system and the acidic juices scarify the seeds thus improving the germination rate for the seeds eventually excreted.

One thing is for certain. A diversity of gardening-knowledge tools, including scarification, can open new vistas to the herbalist, to the vegetable gardener, or to the forester. Knowledge makes one adaptable and thus more likely to increase in the fruits of his labors.

References and Resources:

The World Vegetable Center: Crop Management in Vegetable Production