How to Winterize Bees: A Complete Winter Preparation Guide
Protect your colonies through winter — feeding, insulation, ventilation, mite treatment, and wind protection. Keep your bees alive until spring.
The Steps
Test and treat for varroa mites in late summer (August–September)
Ensure the colony has enough honey stores (60–90 lbs for most US climates)
Feed 2:1 sugar syrup if stores are insufficient, or add candy boards
Reduce the entrance to prevent mice and improve heat retention
Add insulation above the inner cover with a quilt box or insulation board
Ensure upper ventilation to prevent moisture buildup inside the hive
Winter kills more colonies than varroa mites, starvation, and disease combined. In many regions, 30–40% of colonies die each winter. The difference between survival and loss usually comes down to preparation done months before the first frost.
Why colonies die in winter
Understanding the causes helps you prevent them:
1. Starvation (most common) — The colony runs out of food before spring nectar flow begins. The cluster can’t move to reach honey just inches away because temperatures are too cold.
2. Moisture/condensation — Warm air from the cluster rises, hits the cold inner cover, and forms water droplets that rain back down. Wet bees die from chilling, even in moderate winter temperatures.
3. Varroa/viruses — Mite-damaged colonies have weaker immune systems and fewer winter bees (the long-lived bees raised in fall that must survive 4–5 months). High mite loads in fall = dead colony by January.
4. Queen failure — The queen dies in fall or stops laying too early. No new winter bees are produced to replace the aging summer workforce.
The winter preparation timeline
August–September: Varroa treatment
This is the most critical step. Treat with formic acid (MAQS) or Apivar after honey supers are removed. Oxalic acid vaporization in late October/November when brood is minimal provides a second treatment.
Test before and after treatment to confirm mite levels are below 1%.
September–October: Assess food stores
Heft (lift one side of) each hive to gauge weight:
- Light — colony may not have enough stores. Feed immediately.
- Moderate — borderline. Consider adding a candy board or fondant above the cluster.
- Heavy — good stores. Monitor through winter.
In most US climates, a colony needs 60–90 pounds of stored honey. In cold northern areas, 80–120 pounds. Hefting is an art — practice by lifting empty hives and comparing.
If stores are insufficient, feed 2:1 sugar syrup (2 parts sugar to 1 part water by weight) until the colony takes it no more, then switch to solid feed (candy boards or dry sugar).
October: Entrance reduction
Install an entrance reducer set to the smallest opening (about ⅜ inch). This:
- Helps the colony defend against mice (which love to nest in warm hives)
- Reduces cold air entering the hive
- Prevents robbing by other colonies
October–November: Ventilation and insulation
Insulate the top, not the sides. Place a quilt box filled with wood shavings or an insulation board (1–2 inches of rigid foam) on top of the inner cover. This prevents condensation — the #1 winter killer.
Add a small upper entrance (a shim between the inner cover and outer cover) for moisture to escape. This is critical — without upper ventilation, even well-fed colonies can die from wet cold.
November: Final checks
- Confirm the cluster is positioned in the lower brood box (move frames of honey to the sides and above the cluster so they can reach it as they move up through winter)
- Remove any queen excluders (they trap the cluster below honey stores)
- Ensure the outer cover fits tightly and won’t blow off in winter storms
- In bear country, install an electric fence before bears begin foraging
Winter monitoring
Once prepared, don’t open the hive in cold weather. Opening breaks the cluster’s thermal seal and can kill bees.
Instead, monitor from the outside:
- Weight — Heft the hive monthly. If it feels light, add emergency feed (dry sugar on newspaper above the cluster).
- Sound — Tap the side of the hive and listen. A soft hum means the cluster is alive and active. Silence is a warning sign.
- Dead bees at the entrance — A few dead bees on the landing board is normal (winter mortality). A pile of dead bees means a dead colony.
- Cleansing flights — On warm days (50°F+), bees should fly out briefly. If no activity on a warm day, something is wrong.
Prepare your bees by controlling mites with our varroa treatment guide, and keep them safe during inspections with a quality bee suit.
Check winter beekeeping supplies on Amazon.
Frequently Asked Questions
When should I start preparing my bees for winter?
Begin winter preparations in late August to early September. The key steps are: (1) treat varroa mites after the honey harvest, (2) ensure adequate food stores, (3) reduce entrance size, and (4) add upper ventilation. In colder climates, add insulation by late October.
How much honey do bees need for winter?
In most US climates (USDA zones 5–8), a colony needs 60–90 lbs of honey to survive winter. In colder northern zones (3–4), plan for 80–120 lbs. In mild southern zones (9–10), 40–50 lbs is usually sufficient. Always heft the hive (lift one side to gauge weight) in late fall — a full colony should feel heavy.
Should I wrap my hives for winter?
Insulate the top (not the sides). Cold alone doesn't kill bees — moisture does. When warm air from the cluster rises and hits a cold ceiling, condensation forms and drips onto the cluster, chilling and killing bees. A quilt box or insulation board above the inner cover prevents this. Wrapping the sides traps moisture and can do more harm than good.
Do bees fly in winter?
Bees don't hibernate — they form a winter cluster and vibrate their flight muscles to generate heat. The cluster contracts to about 70°F at its core. On warm days (above 50°F), they'll take short cleansing flights. A strong colony can maintain cluster temperature down to -40°F outside.