# Wintering with Screened bottom boards



## Michael Bush (Aug 2, 2002)

Mostly I close mine. Some Northern beekeepers have said they left them open and they did well. Others said they left them open and they all died. Some have said in a mild winter they did better open but in a bitter cold winter they died. You'll have to choose.

I think at least a small top entrance is good in cold climates with lots of snow. It allows some top ventilation, an emergency exit if the snow is high and you have a warm day, and an emergency exit if the bottom board gets too many dead bees and the entrance is blocked.

You could always compromise and leave it open a crack.


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## JohnBee (Sep 9, 2004)

I'm glad you posed the question, as this was on my mind also. I am using Betterbee's screened bottom and stand. I have the tray removable from the back side, which faces N.W., and in the winter the wind would really blast up into the hive. I plan on sheltering my hive with plastic trash sacks filled with autumn leaves, and placing duct tape over the screened bottom board slot, but leave maybe a 1/8 inch gap for some air to get in there.

I also have their foam hive-top feeder, which they say can be left on for insulation benefits. I don't know if I'm right on this or not, but with that feeder setting right on top of the frames, I feel I'd be better off removing it and going with the conventional top cover "lifted" just a bit. I also have a small hole in my 2nd deep for escape/ventilation. I'm a noob, so I hope this works. I'm in lower Michigan, btw.


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## bjerm2 (Jun 9, 2004)

I leave mine on all winter. I have not seen any problems over the years of using them. It might be do to the amount of snow in my area, last year I got about 7 feet of the white stuff.
Dan


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## Michael Bush (Aug 2, 2002)

Obviously if the bottom is all snowed in all winter, then there won't be a big draft there. But here it often gets bitter cold and sometimes there is no snow during the bitter cold and sometimes there is. A howling bitter cold wind blowing in the botom seems like a bad idea. I get 60 mph winds sometimes and this last winter it was between -10 and -20 for several weeks.


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## bjerm2 (Jun 9, 2004)

I agree with you MB it is the snow cover. I also get the same cold -20 to -30 with 60 MPH winds. If you do not thave the snow to protect the hives I would most certainly cover up the screens. It's not that of a big deal just this works for me here. If you think about it what ever works in an area for a bee keeeper is the way to do it. Last year was one of the rare years where leaving 150 lbs of honey was not enough. I had to feed in late Feb and keep it up thru most of the summer. To much rain and the temps hovered around 45 degrees from Feb thru May. Then we had nothing but rain for the summer. I really thought I would lose them.
Dan


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## Hayseed (Apr 25, 2004)

"Last year was one of the rare years where leaving 150 lbs of honey was not enough."

How does one know if they're low on stores unless you open the hives? I thought opening the hives in cold weather was a no-no.

Hayseed


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## Michael Bush (Aug 2, 2002)

We get warm days occasionally through the fall and winter where you can peek in. Plus you can heft the back of the hive and see how heavy it is.


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## olddrone (Sep 16, 2004)

I have been using SBB's for more than 40 years. I started using them for ventilation in bringing hives from Florida to upstate NY, but in the winter I used to change to solid boards until I took my bees to Florida in February.

Then one year I got busy and didn't have time to change the boards. I noticed that my hives seemed to winter better!

I stopped going to Florida about 20 years ago, but have continued the SBB's. Some years we have 50 inches, and some 8 inches. Doesn't make a difference. What is most important is LOTS of upper entrance. A clear 1" is best.


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## BeeBear (Jan 20, 2004)

Looking for an answer to the question of "should I leave my screened bottom board open or close it" I found this thread from last fall. Good information, and based on what I read here, I think I'll probably close 'em up. Just wonder if there's any new insights for this winter season.

I am in sourthern Minnesota, and it's not unusual to get very cold temps with no snow. I like the idea of having ventilation, but I really think that leaving the bottom completely open is too much. If I knew we would get early snow, I'd be less concerned.

I have four colonies. I guess I could leave it open on two and close it on two, but this is not enough colonies to really draw any conclusions. I wish there were some magic way of figuring out what is "right for me", but it might be different based on winter weather.


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## Michael Bush (Aug 2, 2002)

If it was me, in MN I'd either close them or only leave them open a crack (if you have a slide in tray of some kind).


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## BjornBee (Feb 7, 2003)

I leave my open all year. Beekeeping 101 tends to cover site selection, with wind as a consideration in site selection. I know some have no choice, but if you do, move your bees from high wind places. Wind effects a hive sometimes whether a screen bottom is in place or not. Advice on wind sites was around long before the screen bottom board became standard as it is now.

You can also have a higher level of drift between colonies with workers, lose queens as they land on the wrong entrance, and cause chilled brood on a higher level. There is nothing good about wind, whether you use a screened bottom or not.

If I absolutely must leave them in an area I know the wind will effect them, I will stack some bales of hay or something else to create a windbreak.


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## Robert Hawkins (May 27, 2005)

Thanks BjornBee, I keep forgetting to mention wind. I have stated that bees don't die from cold. It's it's usually the moisture or them getting downright wet that kills a wintering hive. They can survive cold unless we increase the wind chill. -40 in a 20 knot wind can bee down around -60 wind chill. That's pretty close to their limit especially if you bought their mother from a TX bk this year.

What's the coldest it gets in queen rearing country. 45? Hay bales or sandbags are a cheap fix.

Hawk


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## Jeff (Jun 18, 2004)

I'm with the Midwest crowd on this one. I live in Indiana and we get the bitter cold with little snow and lots of wind. I reduce my bottom entrance, close my SBB's, and wrap my hives for winter and have had excellent results.


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## margot (Jun 25, 2001)

Should a hive top feeder be placed between the inner and outer cover (so bees can access it through the hole in the inner cover) or does it go directly on the top super?


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## Michael Bush (Aug 2, 2002)

They will use the top feeder better (I assume a miller style or something similar) if it's directly on the super. It's a less convaluted route to get to the syrup.


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## MountainCamp (Apr 12, 2002)

I leave my hives that are on SBB open all winter and they do just as well as the one on standard BB. 
All of my hives are on 2 x 6 frames or pallets, so they sit lower to the ground, than some other arrangements.
Wind and air infiltration into the hive is a function of many factors such as friction, boundary layer, flow path, angle of flow, open area, and the exit orifice.
The wind pushes the air perpendicular to the open screen bottom board. The air can go either past the hive or change course and move up into the hive. The path of least resistance is past the hive. 
For any volume of air to move up into the hive an equal volume must be displaced from the hive. This makes the effective open area of the screen bottom board that of all of the cracks, holes, and upper entrances combined.
The next factor that inhibits air from moving up into the hive and affecting the cluster is the cluster. The cluster acts as a plug and blocks up a significant amount of the open area of the hive that is not already blocked by frames and comb.
As flow moves across a surface a boundary layer develops from friction. Simply, the closer to the surface the slower the flow. There is a significant amount of surface area in a hive as compared to open area.

[ November 01, 2005, 08:04 PM: Message edited by: MountainCamp ]


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## BjornBee (Feb 7, 2003)

Mountaincamp, can you re-evaluate and then comment on the above analysis in regards to air moisture percentages, the altitude of air in relationship to density, whether atmospheric pressures involving a "low" or "high" would impact such air movement, and whether sun/shade in wood warming/cooling has any increase or decrease on the ratio considerations, and would paint color have an impact on the last sub-part of the whole?  

BTW, it all made sense to me.


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## Pat Brady (Jan 18, 2005)

I use sbb, and I close them in the winter. I live in a river valley, which is always colder. IMO the wind is the most damageing, so I wrap my hives with roofing paper and place round bales of hay on the west, and north side.


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## Jeff (Jun 18, 2004)

Mountaincamp...when your hives are setting 16" off the ground you need to close the SBB's. Mother nature knows nothing about aerodynamics...its just plain cold!


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## MountainCamp (Apr 12, 2002)

Jeff, Mother Nature knows fluid mechanics as well as thermodynamics.

Last winter our low was -28F, air temperature not wind chill. 
Wind chill affects play almost no role in the clustering of bees. The outer layer of bees act as insulation for the cluster, with the heat generated from within moving out. The temperature in the hive within a few inches of the cluster is the outside ambient temperature.

The cluster does not try to heat the hive space, they only heat the cluster's occupied space. 

As I said, my hives sit on 2x6" frames, however since I live on the top of a hill, flat ground is hard to come by. Some hives sit a foot or so off the ground.

I have had hives blown over with the boxes spread all over and the hives survived temperatures below 0F for the overnight.

I am not telling anyone that they have to do anything, I am simply explaining what I do and why.

[ November 05, 2005, 10:34 AM: Message edited by: MountainCamp ]


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## Michael Bush (Aug 2, 2002)

>I have had hives blown over with the boxes spread all over and the hives survived temperatures below 0F for the overnight.

When I've had them blow over in those temps they all died by the next morning. But then it took 60 mph winds to blow them over. Those kinds of winds are rough and wind chill does matter some if you're out in the wind.


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## Jeff (Jun 18, 2004)

Just kidding about the aerodynamics stuff MC. I like to take the extra precaution and close everything up. It has worked for me so far and I like to stay with what works...course if I had a lot of hives it may not be an option due to time and expense. I think this is one of those "if it works for you...do it."


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## MountainCamp (Apr 12, 2002)

Jeff, I agree with doing what works. Good luck this winter.


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## rdlp18 (Mar 7, 2012)

Jeff said:


> I'm with the Midwest crowd on this one. I live in Indiana and we get the bitter cold with little snow and lots of wind. I reduce my bottom entrance, close my SBB's, and wrap my hives for winter and have had excellent results.


When you say you close your SBB's, how do you actually close them up? Do you insert an IPM board which actually leaves a little bit of space for ventilation? How exactly are you "closing" your screened bottom boards? I live in Chicago and plan on reducing my entrance, wrapping the hive but I wasn't going to close the SBB other than to insert the IPM board.


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## ralittlefield (Apr 25, 2011)

I made my screened bottom boards from the plans here on beesource. They include a plywood insert that slides into grooves below the screen.

http://www.beesource.com/build-it-yourself/ipm-screened-bottom-board/


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