When to feed… Apart from which hemisphere you keep bees in, there are differences in natural pollen and nectar sources that will modify the dates locally. There are considerable differences in attitude, beekeeper to beekeeper. I have generally fed bees later in the season than most, I have not noticed any ill effects from this (this does not mean that my bees have never suffered from dysentery) but that I have been unable to ascribe late feeding as the cause.
I commonly winter in only one Deep langstroth brood box, and providing they store 80 or so pounds of honey I will not feed further.
What to feed… Some beekeepers feed only honey and others feed mostly sugar syrup. There is no right and wrong, because it depends on what race of bee is being considered and their suitability for the conditions that they are being wintered in.
“Normal” nectar is mainly sucrose and water and as it is concentrated by evaporation, the bees add enzymes that invert the sucrose into mainly levulose and dextrose, with a small amount of sucrose left uninverted. The concentration of the resulting honey is so strong that it does not support mould growth.
When bees pack away sugar syrup it is already fairly concentrated and their opportunity to add enzymes is limited, but a small amount of inversion does actually take place.
The difference between stored honey and stored syrup is the ratios of the sugars in the mixture and that stored syrup contains much lower numbers of pollen grains and a smaller amount of the other minor constituents of honey.
Bees that are adapted well to the conditions that they find themselves in can cope alright with the pollen (protein) and as a result they winter OK on honey.
Bees that are not well suited to their wintering conditions tend to suffer from dysentery as the build up of pollen husks causes them to void within the hive. (This could aggravate nosema disease if present.) If these bees are fed syrup instead of honey they are better able to survive wintering in the conditions concerned.
There is a further complication in that bees consuming stores consisting of mainly sugar syrup lose body fat in the process of assimilating the sugar. Depending on whether this fits or not with the weather pattern and spring development of the type of bee, this may or may not be a “problem”. As an example… Many Italianised strains of bee that are wintered inside a trailer out of the elements , they will suffer far fewer losses when wintered on syrup than they would if they have only honey stores. My local “more native” bees are well adapted and manage perfectly well on honey (which is mainly what they get).
How much to feed… This is another factor that is dependant on the race of bee being considered. In my area my bees manage with 60-80 pounds of honey, yet a few miles away another beekeeper with Italianised hybrid bees will feed his colonies until they weigh 90 pounds or even more. In really cold conditions in Canada I have heard of weights of 140-150 pounds being required. From these wide variations it is obvious that you have to get to know your area and prevailing conditions by asking other beekeepers, in your locality, what, and how much, they expect to feed.
What feeder to use… I favour overall wooden feeders that are the same size as the hive that they are intended to fit. I find That top feeders made of wood should be coated with bees wax. This prevents mold or mildew from forming.