More bees starve to death in March and early April than any other time of the year. Healthy hives usually have plenty of food going into winter but weather conditions and raising brood can put a hive at risk. If the weather permits you can peak inside the hive to see where the cluster is located and if they have full frames of honey next to the cluster. You can then move an outside frame next to the cluster to provide available food.
Another option that many beekeepers use is to add some "emergency food" as a precaution. Think of it as cheap insurance! Fondant, Winter Feed, and Candy Blocks are the most common. Note that these foods sources use very little protein that might stimulate early brood production.
Here are two recipes. They are similar in formula but vary as to size of the blocks and additives.
Recipe for candy blocks (1-10 hives)
1 qt water - bring to a boil in a 16 qt pot (I use a canning kettle)
Add 1/4 c lemon juice
Slowly add 15 lbs. white sugar
Heat on high, stirring constantly to 242 degrees
Turn off heat
Add 1 lb. honey
Stir in 5 lbs. more sugar
Method using cookie sheets or small wood frames:
Use a cookie sheet with rim.
Put piece of wax paper (Optional, easier to remove)
Pour into sheets, about ½” thick
After cool, score in blocks with knife, then break into pieces
Recipe for small candy blocks (1-2 hives) from Ron
1 tsp lemon juice,
2 cups sugar,
3 tbsp water,
4 minutes in my microwave.
I use a 4 cup pyrex cup to hold the mixture then pour into cut off milk jugs and let it set.
There are many similar recipes for making candy blocks. You can google to search for others. It can be a little confusing due to the additives that some advocate. That is a decision for you to make.
Try to avoid protein powder.
Some use white vinegar instead of lemon juice.
Other additives: Honey Bee Healthy, HFCS, Mega Bee Protein powder are some of the more common ones.
If you need large quantities, you can double the above recipe. If the formula gets too large a stove cooktop burner may not be able to heat it properly.
Below are a few pictures showing larger blocks and candy boards.
Large frames, almost like an inner cover with a thicker frame. Often put on before winter.
This is what the frames look like before adding the sugar solution.
Note the candy board is about 50% used up by the bees.
The size is up to you, Larger is a l;ittle more work, but lasts longer.
Smaller blocks are very easy to use. Add several to last longer. Note the spacer!