There are several candidates for the oldest viable seed:
Carbon-dated
The oldest carbon-14-dated seed that has grown into a viable plant was Silene stenophylla, an Arctic flower native to Siberia. Radiocarbon dating has confirmed an age of 31,800 ±300 years for the seeds. In 2007, more than 600,000 frozen mature and immature seeds were found buried in 70 squirrel hibernation burrows below the permafrost near the banks of the Kolyma River. Believed to have been buried by Arctic ground squirrels, which had damaged the mature seeds to prevent germination in the burrow; however, three of the immature seeds contained viable embryos. Scientists extracted the embryos and successfully germinated plants in vitro which grew, flowered and created viable seeds of their own. The shape of the flowers differed from that of modern S. stenophylla with the petals being longer and more widely spaced than modern versions of the plant. Seeds produced by the regenerated plants germinated at a 100% success rate, compared with 90% for modern plants. Calculations of the γradiation dose accumulated by the seeds since burial gave a reading of 0.07 kGy, the highest maximal dose recorded for seeds that have remained viable.
The oldest mature seed that has grown into a viable plant was a Judean date palm seed about 2,000 years old, recovered from excavations at Herod the Great's palace on Masada in Israel. It had been preserved in a cool, dry place, not by freezing. It was germinated in 2005..
The third oldest viable seed recorded is the carbon-14-dated 1,300-year-old sacred lotus, recovered from a dry lake bed in northeastern China in 1995.
Anecdotal
In December, 2009, a Turkish newspaper reported a claim that a 4,000-year-old lentil had been successfully germinated.
In 1954 an Arctic lupine seed, in glacial sediments believed to be 10,000 years old or older, was found in the Yukon Territory. The seed was germinated in 1966. Later, new dating techniques revealed that the seeds were likely modern seeds contaminating ancient rodent burrows.
