I talked with a beekeeper today who manages 1000 colonies. He says anything more than one deep is too much room , and then puts an excluder on this single brood box. My experience is that the bees need more space. My mentor when i got my first bees in 2008 told me two deeps were standard, or two deeps and a medium, depending on time of year. I tend to make sure the bees have enough room and that means at least two deeps. (I don't use queen excluders.)I don't see how a strong colony can build up in the space of a single deep and not swarm -but this beekeeper said they make a lot of splits (to sell or to cover winter losses) so maybe that's the reason. Would be interested in hearing thoughts on this.
It's all in the math and the management
An average Q lays between 1500-2000 eggs per day. 2000 x21days is 42000 brood cells before the first egg emerges as an adult.
There are aprox 4500 cells per side on a deep frame,9000 per frame x 10 frames is 90,000 available cells in a deep.Plenty of room.That's the math.
Swarm season is generally initiated by the massive influx of spring pollen and usually precedes the main honey flow,although in my area they tend to overlap.Many commercials are in areas where the honey flow is after the main swarm season,like sweet clover or canola.
So by splitting and providing sufficient space for all the extra bees at the proper time,one can reduce swarming and also make a crop.And a hive that swarms,with a later honey flow,can still make some honey. That's the management.
Jack is completely right...it is all in the math and management.
I happen to think that two deeps as a brood nest is way to much room and is a major part of the reason so many new beekeepers fail. I personally run a deep and a medium, with the medium on the bottom. The medium provides some extra space when the 'management' is late or lacking, and the deep on the top makes it easy to make splits. I always use an excluder, but that is personal preference and is not necessary.
There's some who swear by single deep brooders and just put extra honey supers on to give more room. I'm only going into my 2nd year, my hive survived winter and i have a deep-medium brood box setup. I'm already watching closely as my first inspection last week showed both boxes almost full of bees, brood and pollen/honey. I may put another medium brooder on. I'd prefer to just split but it's still too early here so I hope I can do that before adding another box.
It's all about timing and strength of the hive. In our area the main flow starts May 1st and only lasts about a month. If you have a single with 5 or 6 or frames of bees/brood right now that's about right. Weather permitting, they will build up to a nice single just as the flow starts and if you add a queen excluder and a drawn super at the end of April you can usually get a super or two of black locust honey per hive. I bottom super after the first one is half full. Plus there are other benefits as well. It seems like the mites don't build up as bad as they do when they're in a double deep. Also I feed mine in the summer with a 2 gallon bucket on top of the inner cover with the telescoping cover on top with a brick on top of that. (Thanks crazy Roland). You should try running a few like this to see how you like it. Eventually I will probably run all singles.