Seed germination

Seaweeds contain growth hormones which help seeds to germinate

Seaweed can be used as a natural germination aid for seeds by adding it to the soil or by using a seaweed extract as a seed soak.
To use it as a seed soak, you can mix a small amount of seaweed extract/liquid feed with water and then soak the seeds in the solution for 24 hours before planting them. The seaweed extract can provide the seeds with nutrients and hormones that stimulate germination.

To use seaweed in the soil, you can mix dried seaweed into the soil before planting the seeds. The seaweed will break down over time and release nutrients that can help promote seed germination.

If you want to make your own seaweed liquid fertiliser here's a good blog post: https://www.milkwood.net/2016/07/04/making-seaweed-fertilizer-added-nettles-comfrey-borage/

References:

https://link.springer.com/article/10.1007/s42452-020-03603-3

More uses of seaweed in Agriculture: