In about 1980, when I lived in Spokane, I grew an avocado tree from a seed. Actually, it was probably my husband who grew it. I vaguely remember him teaching me the proper way to poke toothpicks into the seed so it can sit half-submerged in water. Like this:
That seed sprouted, and we planted it in a pot. Unfortunately, our cats liked the avocado tree. Every time it set out leaf buds, the cats nibbled them off. The tree kept growing, and the cats kept nibbling, until we had a stick about ten inches tall. Then Wickersham, the black-and-white cat, curled his big self in the avocado pot and snapped the stick at dirt level. I've tried dozens of times, but I haven't been able to get anything more than a slimy avocado seed since.
My daughter did the toothpick-poking this time. We have a taproot, and some smaller roots are starting to grow.
And the slightest nub of a sprout has begun to poke out the top.
When the seedling gets bigger, we'll put it in a pot for a while and keep it inside by a window, so I can take care of it. I stink at yard work, so I'm hesitant to plant it outside.
Good thing I don't have cats.