Winter is unique amongst the seasons in that no outdoors Crops apart from Winter Seeds will grow, and all Grass, Weeds, and most tilled soil (including all fertilizer, even if the tile remains tilled) will all be removed at the start of the season. Bee Houses will also not produce honey during winter. Finally, standard trees, including those planted on the farm (except fruit trees) do not grow in winter unless Tree Fertilizer is applied.
Overall, with plant growth stopped Winter can become a challenging season for farmers, leaving only animal produce and the greenhouse as be the mainstay of their farm produce. However, the reduced intensity of farming makes it an excellent season for other activities, including foraging, The Mines/Skull Cavern exploration, fishing, digging at artifact spots, and gift-giving - with nine birthdays, Winter is tied for most birthdays in the season with Summer. It also makes it easier to obtain Farm and Tool upgrades without impacting normal routines.
Animals require additional care during this season, as they cannot go outside due to the cold. Providing them with a heater will also make them happier. Additionally, due to the lack of grass and weeds, Fiber and Hay are more difficult to obtain outdoors. However fiber still can be found in The Mines and Mutant Bug Lair, or alternatively grown with Fiber Seeds. Hay can be acquired at Marnie's Ranch, randomly gifted in the mail from her. It can also be obtained as a byproduct of Wheat grown in the Greenhouse.
There are several winter events and festivals which give the player unique opportunities to acquire items. One takes place early in the month and one takes place towards the end, marking the end of the year in the Valley. An additional Night Market activity also starts halfway through the season.
The Nautilus Shell can be found at The Beach only in Winter. In addition, the items shown below can be found while foraging during Winter. The percentages provided for each location are the percentage of all foraged items in the location that will (on average) be the specified item. 
These fish can only be caught in the submarine ride at the Night Market during Winter 15-17, or by using Magic Bait in the South-western corner of the beach. They can be caught during any weather, and at any time while the market is open (5pm – 2am).
↑The foraged items that can spawn in a given location each season are determined by GameLocation::spawnObjects in the game code, using input from the data file Content\Locations.xnb. The percentages provided here have been normalized to ensure that the percentages sum to 100% for each location. The data was normalized by:
Calculating the sum of all percentages listed in Locations.xnb for Winter