• Puree the rhubarb in your Vitamix blender or food processor, along with the water to get it started. You may need to do this in 2 batches.
• Put the rhubarb puree into a clean jelly or nut bag, and let it hang over a large bowl to allow the juice to drip out. Don't press or squeeze the bag aggressively or the pulp may come through and this will make your jelly cloudy. I do squeeze it a little bit, though, to move it along. It can help to have a jelly strainer, which is made for this purpose. You want to end up with 3 1/2 cups liquid.
• Put the rhubarb juice in a large stainless steel pot or saucepan. Stir in the sugar, the lemon juice, and the vanilla bean seeds. Bring the mixture to a boil, stirring almost constantly.
• Once the mixture has reached a full rolling boil, let it fully boil for 3 minutes. It may foam up so stay right by it. Stirring is ok.
• After 3 minutes, stir in the pectin, and bring it back to a full, rolling boil. Boil 1 minute. Again it may foam up so be careful.
• Take the jelly off the heat and skim off any foam that is on the surface. Fill your sterilized jars to within 1/4 inch of the top.

If you are canning

• Wipe down the rims of the jars to remove any spilled jelly, then attach the lids and screw them, but don't over-tighten.
• Process for 10 minutes in a boiling-water canner.

If you aren't canning

• Let cool and then cap and refrigerate.