January is a another quiet month in the garden with not so much to do in the garden. On mild days it's good to try a bit of weeding; after the rain and frost time to the ground seems to yield the weeds more easily. It is cold and frosty for the birds as well so its a good time to look after the wildlife . In addition to putting food out, birdbaths can easily freeze over which deprives the birds of a much-needed source of water. Shrubs with berries are really important for the birds, and by this time of year often the birds have all but eaten all the available berries which makes a regular top up of the bird feeders essential to the survival of as many birds as possible through the winter months.
I think gardening in January is best done in doors, planning, seed catalogues and thinking rather than doing.
And on bad weather days, of which there are always plenty in January, its armchair gardening with the seed catalogues planning for the spring and deciding which new veg to try.