I have a Dracaena Draco that I grew from seed in 1989. 18 months ago it flowered and I now have ten small branches coming out of the top of the trunk.

The other day while I was disposing of the old flower stalk I noticed a depression in the middle of the top of the trunk about 3 inches deep full of soil.

I cleaned the soil out. My question is will this depression eventually harden? I am a little scared that if I get too much rain it will fill up with water and possibilly rot the tree.