Last year at the end of November I started this experiment: grow an avocado plant. I didn’t trow away the seed after I finished on and I followed some online guides.
To start growing an avocado, you need to pierce the seed with toothpicks and put the bottom part into a glass of water. Change the water every 10 days and add a bit of soil in the glass to give nutriment to the seed. After 2 weeks you will see the first root growing.