Don ~
I would not plant the tuber outside, instead plant in in a large pot - DO NOT water!!!. It will remain dormant until next summer. It will grow when it is ready, not when you want it to!

Voodoo Lily is a generic term for many tuberous aroids that have a stinky bloom. It could be Amorphophallus spp.; Typhonium spp.; Sauromatum spp. or another aroid.

Where did you get your tuber from? Is there any other information with it?

You possibly have Amorphophallus konjac as they eventually grow large tubers, like yours that are are a reddish/purple color

Check out: snowsexotics.com, aroid.org, or google voodoo lily for more info. I recognize that you are a beginner and want to help so you will have success with your tuber/plant.

Wow, none of my VooDoo lily bulbs ever get that large. the largest one I have had was about 2" wide. They seem to multiply rather than get very large. I think my bulb was labeled Arum cornutum when I bought it however I believe the taxonomist now have it classified as Sauromatum glutatum but next week it may be something else. Those taxonomist are such fickled people.

I had a good experience with this plant last spring but it shows my lack of experience with the plant and how as Krazyaroider said, the bulbs sprout when they are ready to. I have had this plant growing for about 3 years in a 2 gallon pot. I carry the pot through the winter in my garage which gets cold but does not freeze. This past spring the plant did not come up at all. I had sowed some red leafed millet seed in a portion of a very large (35 gallon) pot that had something else growing in it that died. I dug a portion of the millet out to give to a friend and decided to pour some of the soil from the VooDoo lily pot in to fill the void left after I removed the millet seedlings. When the soil went into the hole I realized the VooDoo lilies were still there but just not up yet. I scooped the soil along with the bulbs back into the original 2 gallon pot. I missed a very small bulb that was not much bigger than a pea. A single leaf came up in a few weeks; it was really small, perhaps 5 inches tall and 4 inches wide. The leaf which never seemed to get any larger persisted until the first of August then it died. As it was withering additional leaves began to come up in its place. Now there are probably 20 leaves with a few of them about 2½ feet tall. There are also additional bulbs that have come up around the main plant. This has become a massive plant. Maybe the larger pot giving it a larger rootrun makes it happy.

I really do like this plant. It is a good conversation peice.

Leon