How late in the year can you combine colonies?

[Do224]

I presume there comes a point in the late summer/autumn when it becomes too late to be combining colonies.

When (roughly) would this be and what are the deciding factors?

 

[jenkinsbrynmair]

you can unite them any time really but you should really have everything sorted mid to late September

 

[polymath]

I have combined as late as september, to be honest i don't see an issue as long as there are stores and the weather is warm enough so they are not clustering.

 

[ericbeaumont]

I found that uniting Sep/Oct was odd: bees could barely be bothered to chew through. After a week I took the paper away and put them together.

Better time to unite is at the beginning of a nectar flow: strong colonies bring in more.

 

[oliver90owner]

About ten years ago, I remember uniting in the last week in September. Hopelessly queenless colony underneath and a nuc box on top - half the bottom box covered with a piece of board and a piece of thin board sloped across the board to deflect as much rain as possible.

They were then left until mid-December before re-arranging the frames. Another 5/6 frame box was sorted with a proper floor at that time. There was snow on the ground, as I recall.

IIRC, another superceding colony (old queen was removed) was split into two 6-frame boxes at that time. One was mated successfully and one was not, but both went through the winter quite easily.

A heart bypass op intervened at short notice (just two days to sort everything out), hence the rush and time between the next interventions.

 

[Curly green finger's]

I found that uniting Sep/Oct was odd: bees could barely be bothered to chew through. After a week I took the paper away and put them together.

Better time to unite is at the beginning of a nectar flow: strong colonies bring in more.

I agree uniting before a flow is a good idea and works well but we can always stimulate with syrup to mimmick a nectar flow.
After the summer flow has finished up here Im uniting some colonys to prep for autumn treatments. I'm going to have to do it in stages this season.
If the Heather comes off.

Imo September is probably to late up here any way.