An internet search for answers revealed little. One search using the words "Sarah Palin organic gardening" uncovered a page from the Huffington Post that addresses organic gardening but not Palin--the reason it came up in my results was that on the same page there was a link to a poll that asks "Is Sarah Palin's lipliner a tattoo?" I could not find any evidence that Joe Biden gardened either, though a gardener dedicated her blog post to her positive interactions with the lawmaker.
Perhaps a career in politics leaves little time for gardening. So instead consider some of their positions on the environment. We've all heard that Palin supports drilling for oil in the Arctic National Wildlife Refuge; Biden opposes it. Another noteworthy observation is that the Humane Society has agreed with 80% of Biden's positions, and that he had advocated for more compliance with mercury regulations as well as an increase in cleanup of this dangerous substance.
Whoever we elect for #1 and #2 should appreciate the importance of gardening for many of us, and the advantages shifting the emphasis more toward locally grown food. They wouldn't be the first executives to consider it, as this video shows.