As autumn settles over the Pacific Northwest, beekeepers need to prepare their colonies for the long, wet winter ahead. Unlike regions with harsh, dry cold, our mild but damp climate presents unique challenges. Here’s how to get your hives ready for the dormant season.

Timing is Everything
Begin your winter preparations in late September through early October, before temperatures consistently drop below 50°F. You want to complete major hive manipulations while bees are still active enough to reorganize themselves but early enough that they won’t be raising significant brood.

Consolidating the Brood
Strong, compact colonies survive winter better than sprawling ones. Open your hive and locate frames containing brood, eggs, and larvae. These should be consolidated into the center of the bottom box, creating a tight cluster area. Remove any frames with only pollen or empty comb from the brood chamber’s center.
If you’re running multiple boxes and find brood spread across them, move all brood frames to the bottom box. The queen and her winter cluster will naturally form around this brood nest. Bees move upward during winter to access food stores, so they need resources directly above them.

Sorting Your Resources
Once brood is consolidated, arrange your food stores strategically. Frames heavy with capped honey should surround the brood nest and fill the boxes above. In the Pacific Northwest, a healthy colony needs 60-80 pounds of honey stores—more than drier climates due to our longer active season and the energy required to manage moisture.

Position frames in this order: honey frames on the outside edges of the bottom box, then brood in the center. The top box should be entirely honey. Remove any frames that are empty, contain only pollen, or show signs of mold or fermentation. Replace weak frames with drawn comb if available, or simply reduce the hive’s size by removing boxes the bees cannot adequately cover and defend.

If stores are light, feed heavy syrup (2:1 sugar to water) immediately, or provide fondant or candy boards later in the season when bees won’t take liquid feed.

Fall Oxalic Acid Treatment
Varroa mite control is essential before winter, as mites multiply throughout the season and can devastate colonies during the long months when bees cannot easily replace lost population. Fall is an ideal time for oxalic acid treatment in the Pacific Northwest because the brood cycle naturally slows or stops, making the treatment most effective.

Oxalic acid works by contact, killing mites on adult bees but not those protected inside capped brood cells. This is why late fall treatment, when brood is minimal or absent, achieves the best results. In our region, this typically means treating in November or December when temperatures still allow for brief hive openings on milder days.
You can apply oxalic acid through two primary methods: vaporization or dribble. Vaporization involves heating oxalic acid crystals with a specialized vaporizer, which creates a fog that coats the bees and kills mites. This method is highly effective and doesn’t add moisture to the hive. Dribble application involves mixing oxalic acid with sugar syrup and slowly pouring it between frames where bees cluster. Each method has its advocates, though vaporization is gaining popularity for its efficiency and lower stress on colonies.

Always wear proper protective equipment including respirator, gloves, and eye protection when handling oxalic acid, which is caustic and can cause serious injury. Follow product instructions precisely regarding dosage and application timing. Most beekeepers in the Pacific Northwest find that a single treatment in late November or early December, when the colony is broodless, provides excellent mite knockdown heading into winter.
Installing Quilt Boxes

Moisture management is critical in our climate. Quilt boxes—shallow boxes filled with absorbent material—sit above the inner cover and create a buffer zone that absorbs moisture rising from the cluster without allowing it to condense and drip back onto the bees.

To install a quilt box, construct or purchase a shallow box (3-4 inches deep) that fits your hive dimensions. Staple hardware cloth or burlap across the bottom to contain your absorbent material. Fill the box with wood shavings, sawdust, or burlap scraps, leaving about an inch of space at the top. Avoid cedar shavings, which can be irritating.

Place the quilt box directly above your inner cover if it has ventilation holes, or remove the inner cover entirely and place the quilt box on top of your uppermost honey super. The telescoping cover goes on top of the quilt box. Some beekeepers cut a small notch in the quilt box’s upper edge to ensure top ventilation.

Final Touches
Reduce your entrance to prevent robbing and help the colony defend against mice. Ensure your hive is level with a slight forward tilt so any condensation drains out rather than pooling inside. Check that your hive has adequate weight—tip it gently from behind to assess stores.

Most importantly, resist the urge to open your hive during winter. Quick peeks on warmer days can break the propolis seal and disrupt the cluster. Trust your preparation work, and your bees will reward you with a strong colony come spring.