Just curious, how do you decide its time to super up. Environmental cues such as first dandelion? Heating degree days? Especially interested in those with experience in the New England area.
Is there harm in supering too "early"?
The only harm in supering too early is if the foundation (if it's undrawn) sags and get's ruined or the bees chew up the combs because there's not a nectar flow on. I figure if the boxes the bees are in are 80% full it's time to add some room before they decide it's too crowded.
If I have drawn comb and the nectar is flowing, I'll put a lot of it one without worrying about it sagging. If I only have foundation, I hate to put it on too early and end up with sagging foundation. Sometimes it even falls out of the frame.
The bees need more comb that just enough to store things in during a flow. They need surface area to evaporate and ripen the honey, so I like to add several supers of drawn comb if I have it.
This is one of the reasons I started the post baiting up. So taking into account what Michael has said. To get the bees going up you can bait them up(assuming brood chambers are well filled with bees) by putting two frames of honey up into the supers and two frames of foundations down into the active broodnest in a every other frame manner. Now I should state that I use no chem's so it is safe for me to manipulate combs as needed. So by baiting up you also can ease some of the foundation chewing and draw the bees up a bit quicker sometimes.
Environmental cues such as first dandelion?
Yes this is good to watch for and I normally put supers on around dandelion time. I know commercial beekeepers in VT are supering up now probably right on fruit bloom or just before it.
If you already know there is some kind of nector flow on, forget about everything except whats going on in the hive. Hive activity is one main key on when add supers. I've heard several different figures from different people/sources about when to super....60%, 70, 80 drawn/capped. I think anywhere in that area is acceptable. Yeah, if you already have drawn out comb, you can even go ahead and add SEVERAL at a time. I am a big fan off 'baiting' as well and think it works great, just be super cautious if you are medicating and really wouldn't recommend if anywhere in that time frame.