No way to say. Ambient air temps are more a critical consideration for above ground plantings, and all bulbs are not equally cold hardy. The size (large soil mass)of the container will help moderate the tendency of the soil temp to equalize with air temps over night, but whether it's whether its moderating effects are sufficient depends on several other factors - mainly how low the air temperature actually drops.

Growth has probably begun in most bulbs you are growing in zone 5. 6" garden soil temperatures are very unlikely to drop below freezing now - surely not below 28* or so. I would pick about 25* as the absolute lowest actual soil temperature I would risk exposing the emerging bulbs to. If you estimate the night (or day, for that matter) temperatures will drop low enough (20-22*?) so that actual soil temps might fall below 25 - 28*, I would keep them protected.

Additionally, there is no advantage to having them outside until they emerge and able to take advantage of the additional light outdoors to increase photosynthesis, primarily a consideration for next year's flowering. This years blooms are bought and paid for (energy already stored in the bulb).

Al

Ok...well since I posted that, I went home last night and found the IN GROUND tulips poking up through. I'm going to take your advice and protect the smaller containers, which house the smaller bulbs, but the biggies with the Tulips will get an experiment in 'toughing it out.'

It's my first time growing bulbs in containers...so we'll see what happens.
Thanks!

Just remember that geo-thermal heat substantially effects soil temperatures. It is very unusual for 6 inch (garden or bed) soil temperatures to drop below 25* in zone 5, but very common in containers. You shouldn't use what's happening in the garden as a barometer for what will happen in containers. 6" garden soil temps will only be affected in a minor way if you get a hard freeze, but container soil temps will come much closer/very close to equalizing with air temperatures. Let projected air temperatures and your considered judgment be your guide.

Al

I assume we're talking spring flowering bulbs...that were planted in pots and left in a coldcellar over winter.
The containers you speak of....4"....and up are holding such bulbs.
I'm assuming a bulkhead referred to is such a place...a storage place that is kept near the above freezing mark.

Just for amusement, let's discuss what a bulb does when planted in October in the ground.

First, it is planted at that time so as to ensure it gains roots...because without roots, the bulb in the ground will freeze...and when, in the ground, spring arrives with its warmer weather, the bulb...without roots ...having had no protection...soon rots and is on the dinner menu of bugs.

Such a bulb in the pot....in a 4" pot...would it, could it, grow roots when placed into a coldcellar for the required 14 + weeks.
Without roots, there is no reason to plant it in the grarden...it wont come to anything.

The tulips in the garden, popping up, have their roots because they were subjected to the cold and because they have roots were protected from such cold.

I suspect some of the bulbs anyway cant possibly have such roots formed and when planted cannot come to anything except fodder for squirrels and such.

That's good to know...Maybe I should take a spoon and check them? Or just wait, and if nothing happens, well, it was obviously a bad plan?

Yes, the bulk-head is that place in my basement that is accessed from the outside of the house:

{{gwi:11701}}

We have another door at the bottom of the stairs (you don't see one in this picture), so the temperature in the stairwell is considerably colder than the basement. It is my OPINION that the temperature in the bulkhead was not much warmer than the outside temp, since there is no seal on the bulkhead door, and air flows in and out of there through the cracks. It's only bolted down, not sealed.

So that's that.

mm.......I have a similar space under my front porch which I enter from my basement. It has vents outside on the wall of my porch which allows the ambient outside temperature to enter..but not to the point my preserves could freeze.
Honestly, I had to look up the word....I asssociate bulkhead with a ship's walls. So, I've found another meaning for a word. Me, I'd call it a storm shelter.

If the room is as you describe, cold enough to keep temperatures just above freezing, it might very well be sufficient to cool bulbs so they could attain roots.
This is the practice that usually is followed to "force" bulbs.
In other words, if you have been keeping your potted bulbs watered, and foliage results and were to bring them out to a sunny window, they might very well bloom for you within a couple weeks.
They should be watered only sufficiently to keep them from drying out.
The temperature in your bulkhead cannot fluctuate widely....i.e. it cannot go up...to 55....down....to 35...back up to 50....down to 30....
that kind of temperatures defeats the bulbs and probably prevents them ever producing bloom.

I suspect though you haven't given them this potting routine....a 4" pot doesn't speak for such forcing.
Usually, this operation involves 5 or 6 bulbs in a 6" pot.

The storage though, if some of the bulbs have been kept cool, they may have produced roots. In this case then, you might plant them when the soil makes that possible. Do it as soon as you can. Who knows, nature does funny things.
Even if your bulbs...if they are tulips especially...don't flower in '07, their planting may just allow them to flower in '08. They may push up some foliage and this ---if they don't flower, should be allowed to wither on the vine, go brown as though they did in fact bloom.
This then sends the starches and sugars down into the bulb to produce something the next season.

I have no idea what the temperature has been doing in there; I'm not a scientist, and I don't garden scientifically, so there was no note-taking, temperature monitoring, or anything like that going on.

I planted them in the containers, watered them, and tossed them in the stairwell. I watered them once again about 3 weeks ago.

I was very excited yesterday to find that the bigger patio-sized containers did, in fact, have sprouts peeking through the surface!!! Hopefully they will also have bloom. Time will tell.

I decided to bring the little ones back in the house, and set those all on my windowsill. Will keep you posted on progress.