We have had great success with overwintering bees in Colorado with the following setup and procedure with no losses in the past three winters. While the genetics of the bees have a lot to do with our overwintering success, we share our setup and process in case it helps others improve their success rate overwintering bees in Colorado.
- Telescoping Cover
- Notched Inner Cover
- 2 Deep Boxes with ~100lbs Honey
- Slatted Rack
- Screened Bottom Board (open year round)
Bees in Winter
One way to think about a colony of bees in the winter is to picture the colony as a small animal like a rabbit or a chicken. These animals fluff up their fur or down to insulate the core of their bodies, and by doing that they can survive very low temperatures as long as they are protected from the elements and excess humidity. Similarly, a cluster of bees has a mantle and a core, where the mantle functions as down, with bees in the mantle regulating temperature in the core, where the queen is protected. With too much humidity, a warm hive in a cold day will have condensation form, which can drip water down into the hive getting the cluster wet. When bees get wet, their attempts to heat the core instead cool it, through evaporative cooling, and the whole colony can perish. As long as they are dry, the bees can stay warm.
Since cooler air holds less humidity, we use basic ventilation to move the warmer, humid air over the cluster out of the hive. The open screened bottom board and entrance, combined with the notched inner cover (with the notch to the back, and a slight gap from the telescoping cover) allows cool air to enter the hive from the bottom, creating enough air disturbance to move hot, humid air out of the notch in the inner cover.
Somewhat counterintuitively this means focusing more on ventilation than heat even in very cold winter temperatures. We also level our hives side-to-side but tilt them very slightly forward so that if condensation forms it does not drop directly down to the center of the hive, where the cluster is.
The Slatted Rack
A slatted rack provides extra vertical space between the bottom board and the bottom brood box, with slats that run parallel to the frames in your hive, so that the bees do not fill it with comb. A slatted rack helps a colony maintain an ideal temperature year-round, with space inside the hive for fanning bees inside the hive, who would otherwise beard. They also reduce drafts, while allowing ventilation through the screened bottom board in Winter. In Spring, the slatted rack allows the queen to lay lower in the bottom frames, giving her more space and reducing the urge to swarm in Spring. A slatted rack also helps with varroa control in combination with a screened bottom board, since mites groomed off by the bees cannot jump far enough to get back to the frames. It’s an essential component on every hive we manage.
Preparing the Hives for Winter
We harvest honey only after ensuring that every colony has at least 100lbs of honey available for winter, and we reserve several (deep) frames per hive in reserve in case a colony builds up quickly in Spring and needs extra stores. Deeps stored over the Winter need to be frozen to kill any wax moths or pests that may be in the comb, and protected from rodents. For that reason, we tend to harvest honey close to the last frost, when the incoming nectar dwindles and we are certain of the stores they have for Winter.
Inside the hive we ensure that the brood nest is centered in the bottom box, with at least two full frames of honey to either side – some of our colonies remain larger populations in the Autumn and others backfill the broodnest with honey, forcing the queen to take a break as they would before a swarm in Spring. If you see this, don’t be alarmed. This has been identified as a means of varroa resistance in colonies, where bees eliminate the ability of varroa to take hold by pausing brood production after the Winter bees have emerged.
Harvesting Honey Sustainably
We harvest excess honey once our colonies are full and we have reserved 6 or so deep frames per colony.
We primarily use deep frames for honey. Our reason for this is that we are less concerned with honey production than with successful overwintering and build up again in Spring, without swarming. We use an extractor and take care to not disturb the comb while uncapping. Drawn comb is one of the most valuable resources your bees have, taking 8 times the resources as honey to fill it. If you have extracted deep frames to give your bees in Spring, you’ll be able to reduce the swarm instinct by adding new drawn comb that the bees can use for the Spring buildup, especially if they are thrifty with their honey. You can also use drawn deep frames to establish additional colonies in the Spring if your bees are successful, and you will appreciate any leftover reserve honey if you establish new colonies. You will see when you receive your bees from us that they have a good store of honey in spite have never having been fed sugar syrup – keeping extra frames in reserve lets us feed our new colonies honey even when the mother colony depleted their stores.
Once we’ve extracted our frames, we return them to the colonies so that the bees can spend the remaining nice days after the freeze cleaning the remaining honey from the comb. We place the boxes for cleanup over the inner cover to encourage the bees to bring the remaining resources down. Once they have cleaned up the comb we remove the comb and store it in deep boxes between two top covers, so that mice cannot get inside. We keep our extra honey stores and drawn comb this way in our uninsulated garage over the Winter, the cold temperatures kill wax moths and hive beetles. An outdoor shed is a good alternative if you have a garage that doesn’t get to freezing temperatures.