Experimenting with Avocado Seeds

What makes it easier for some seeds to grow roots faster than others?

Hypothesis 1: warm temperature, simulating the environment where avocados grow, mainly in Central & South America, California, parts of the Caribbean, and other warm places in the world.

When I started my first tree back in December 2008, I poked 3 toothpicks into the avocado seed, filled a cup of water, and placed the seed halfway in the water. (see picture) I put the cup in the kitchen on the counter where it wasn't getting any direct sunlight and temperatures were around 68 - 74 F. After a while, my wife put it in a cupboard. I still checked on it every few days and added water to maintain the water level at about the halfway mark of the seed.

This seed did nothing until about February 2009, after which it started a root. The seed cracked from top to bottom and in the middle of this crack the root went down into the water. After a week or two, the tree started to grow up. It looked like a purple stick coming out of the seed. Soon it started to have leaves and continued to grow taller and the leaves got bigger.

By April or May it had about 5 to 8 leaves and the tree was about 6 inches tall. I decided to plant it in my back yard. I live in the western part of Washington state where the weather is usually pretty mild except the last 3 years where we've had hot summers in the 80s & 90s and cold winters with freezing temperatures and snow. Last year I woke up and found 14" of snow outside. It should be interesting to watch how it does during the winter. This summer when temperatures reached into the 80s and 90s for weeks at a time, some of the leaves started turning brown. I watered it w/ about half a gallon per day or every other day. To solve this problem, I ripped some leafy branches from a bush and stuck them in the ground around my tree to give it some shade. It worked, and the tree did much better after that.

In October the temperatures have already dropped below freezing some nights and I used an old styrofoam cooler to cover my tree. I cut out the top of the cooler, flipped it upside down and covered the tree to keep it from freezing at night. Avocado trees need temperatures to be above 45 F. I'm pushing the limits here in Washington.