Don't mix varieties in the same container, since they vary in their dates of flowering - according to the U of MN Extersion service website.

Plant the bulbs close together in the pot. Usually 6 tulip bulbs, 3 hyacinths, 6 daffodils, or 15 crocus, will fit into a 6-inch pot.

Planters - like those from WWF - that you see with crocus, daffs, tulips and muscari blooming at the same time have been put together at the last minute with individually forced bulbs. If you don't mind the crocus blooming first and then the tulips or daffs, you can plant them together and chill the grouping for the longest time required for any of the bulbs.

Depending on the type of bulb, the chilling period varies from 6 to 15 weeks. Tulips need the longest, taking from 14 to 15 weeks to root fully. Daffodils take 12-13 weeks. Hyacinths and crocus require 10-12 weeks. Scilla and muscari need 8-9 weeks. Chionodoxa, freesias and iris reticulata require 6-8 weeks. These bulbs need to be fully rooted to bloom properly.

Probably more information than you wanted to know.

Probably more information than you wanted to know.

No, it's not. That's why I asked the questions. I'm not sure you understood my questions. I know that varieties vary in dates of flowering, that's the point of my question. I also already knew the chilling times, that's why I was asking how they got them to bloom at the same time. What I didn't know was that bulbs are individually forced to do this. How is that done, particularly if they need to be fully rooted?

The number of bulbs you say to put in a pot is more in line with my own experience. I don't know how they put so many. I am not sure that I could physically jam 40 bulbs into a 12 inch pot!

Yes, I understood your questions perfectly well. Using the known chill period requirement for each type of bulb, you could mark a calendar to put each desired type in the pot within it's required chilling/rooting time frame.

Once you bring the pot in from the cold and dark, all of the bulbs - regardless of type - will take 3-4 weeks to come into bloom. And if you've calculated the weeks of chill/rooting time correctly, they should all come into bloom at the same time.

Or you could plant all the different types of bulbs separately and do some extremely careful transplanting - which might also explain the collections.

As for 40 bulbs in a pot, I suppose Muscari, Scilla or Puschkinia, crocus; any of the minor bulbs - but tulips and daffs plus some of the minor bulbs...? I'm sure they're truthful since it's likely some who have ordered collections such as these have actually counted the bulbs afterwards and would have been on the phone to customer service if they were a bulb short.

Ok, thank you for clarifying. I'm still having a little logistical problem - maybe it's just me. I am thinking I would like to try this though, so want to see if I can get it.

Let's start with something relatively easy. Let's say I want to mix one variety of tulip, one variety of daffodil, and one variety of grape hyacinth in the same pot and have them all bloom at the same time. I would start by putting my tulips in the pot, in soil I presume? Then about two weeks later my daffs go in. What have they been doing in the meantime? Staying at room temp? And I guess I would have to push soil aside to get the daffs in there, or else layer which would then, I would think, change the time it takes for the tulips to emerge. Then about four weeks later I add the hyacinths, so same questions, do they stay at room temp in the meantime?

All will bloom in three to four weeks after coming in - I did not know that, that is very very helpful. For other reasons as well, lol! (aside here - I want to do some pots for my front steps that will be blooming at the same time as the outdoor tulips, now I know the timing for that, thank you!)

The 40 bulbs bit - here is one of their descriptions, it is astounding to me:
"A regal collection of favorite TulipsÂapricot 'Beauty Queen', pink 'Gabriella', 'Purple Prince', and 'White Emperor'Âsurrounded by a host of supporting blooms chosen for their sweet smell and guaranteed performance. We pack the bulb pan with six each of the Tulips, two each of heavenly scented Hyacinths 'City of Haarlem' and 'Delft Blue', a dozen each of Anemone 'White Splendour' and the fragrant blue Grape Hyacinths, Muscari armeniacum and M. a. 'Valerie Finnis'. They are rounded out by nearly a dozen Daffodil bulbs chosen from 'Segovia', 'Barrett Browning', and 'Sweetness'. A glorious spring bulb garden, prechilled and ready to begin growing on arrival. Seventy-five bulbs in a 12" stained Ash basket."

I will start small this year. I'd just like to combine a couple of simple varieties to see if I can get them to bloom together. I'll worry about 75 bulbs of 10 varieties some other year!

Thanks for the help, any more advice?

Sounds like it should work for you on that schedule. Bulbs are pretty much self contained so should survive the wait to be planted in your garage or someplace cool (but not in the fridge).

Since forced bulbs are planted shallowly, the tip of the tulip bulbs showing above the dirt line would guide you as to where to put in the daffs; same for the hyacinths. Or space them out in advance leaving room to poke the staggered bulbs in. It'll be in intersting experiment - I haven't forced bulbs for many years, but always did each type in a separate pot so I'd have a long succession of things in bloom.

I guess the bulb/flower growers have the technique down pat, but I'd have trouble cramming 75 bulbs in a 12" pot even if they were all planted on top of each other. Seems there wouldn't be any room for soil.