Rare Ice Spike or staligmite of ice

For the second time (first time February 19, 2013) I was able to spot the rare Ice Spike and this in my own garden. Temperatures dropped below freezing point (-2.5°C) and this created a Ice Spike. 

Ice Spikes can only formed when all circumstances are perfect. Circumstances are influenced by the purity of the water, amount of water, shape of the "container", surrounding temperature, temperature gradient and probably the air circulation and humitidy of the surrounding area.