Seeds that have a hard, impermeable coat will not take up water very easily. Because of this, they may take a long time to germinate. To speed up germination and make seeds take up water better and faster, you can use either of the following pre-germination seed treatment methods.
The hot water method is the easiest, but some plants do not tolerate long time emersion in boiling water. In those cases, try the physical scarification method or the microwave method.
Pre-germination seed treatment methods
- Place the seed in a heat-proof cup (not plastic).
- Pour boiling water over the seeds so they are submerged.
- Let the seeds soak overnight in the water.
- In the morning, you will see that some or all of the seed have swollen.
- Drain the water from the container and pick out the swollen seeds.
This pre-germination seed treatment method erodes or cuts the seed coat (without damaging the seed) so that water can penetrate.
There are several ways in which the seed coat can be weakened.
To make the seed coat thinner:
- rub the seeds in between two layers of sandpaper
- rub the seed against a hand file.
To make an incision in the seed coat (be careful not to damage the seed itself!):
- make a small cut in the seed coat with a knife
- remove a small section (a square millimetre) of the seed coat with nail clippers.
If the other pre-germination seed treatment methods are not successful, try placing the seed in a microwave. This has a similar effect than boiling water. Try microwaving the seed anywhere between 20 seconds to 4 minutes.
Plants with hard seed coats