Oaks are drama queens when it comes to germination. They need a cold, moist period called stratification to convince them winter has passed. Without this, your acorn will just sit there, smug and uncooperative.
Pop your sinking acorns into a ziplock bag with damp (not soaking) peat moss or a paper towel. Seal it and stash it in your fridge for about 6 to 12 weeks. (Just don’t tell your roommates you’re sharing crisper-drawer space with a bag of future trees.)
