Thistle seed in birdseed should undergo a sterilization process before you purchase it. Because North America must import thistle seed from international suppliers, this sterilization process should occur before the thistle seeds enter the United States. Even with this precaution in place, however, some people who feed birds regularly find their thistle seeds sprouting beneath bird feeders. Because thistle seeds fill sock feeders in small amounts, it is not difficult to microwave a small amount of the seeds before you place them into a feeder. This short process may prevent weeds from sprouting under your bird feeders.
Fill a small paper bag approximately 1/3 to 1/2 full of thistle seeds.
Fold or roll the upper edges of the bag back several times to make the bag shorter. Place the paper bag into the microwave oven and ensure the bag is wide open.
Close the microwave and cook the seeds on high for three to five minutes. Remove the bag of seeds from the microwave after the time elapses and allow the seeds to cool.
Fill the sock feeder in the normal fashion.