I have had great success with growing tulips and other bulbs in containers in Zone 6. I place the pots in sheltered spot in garden, away from harsh winds, and totally bury them with fall leaves. Carefully remove leaves in spring when shoots emerge and bring pots to sunny spot.
I'm not sure cardboard alone will offer enough protection.

If the container freezes, you will have a pot full of rotten mush come spring.

Yup, a pot full of rotten mush...that's what I ended up with after potting up bulbs and burying them in piles of leaves. Never again.
Another year I buried the pots in my vegetable garden. That worked fine, but it's just too much work. So I gave up on potting spring bulbs.

This post was edited by pitimpinai on Mon, Sep 15, 14 at 13:50

I agree, much easier to just plant them in the ground and let them do their thing.

If you want blossoms in the house, cut the flower stems.

Thanks everyone,

you saved my time,bulbs and next springs bloom.

-Jay

Oh so that's what happened to me last year. I found a few pots where nothing came up and when I dug into it, just mushy bulbs or roots. I had pots in winter before so could not understand what happened this last year. Seems it froze up.

Thanks for the info, will take more care about those potted up plants on the really cold nights.

Has anyone tried a half barrel for planting? Last year I put all my bulbs straight in the ground and about 50% made it to bloom. This year I want to try something more elevated...

here in my MI .... my ground freezes SOLID .. much deeper than a tulip is planted ... and they dont rot or turn to mush ... but it is high drainage sand ...

its all about water management ... cold is requisite .... but not the variable of failure ...

with water management in pots... the key is ALWAYS ... the media you fill the pot with ... in other words.. if you use a high peat media.. and keep it sodden ... you are already set up for failure ....

FORCING TULIPS IN POTS ... is really pretty easy ... and the link tells how to do it ...

while reading such.. i would key in.. in the length of cold dormancy needed [and how to accomplish it the warmer your zone] ... the media needed ... and how to water such ...

just off the cuff... here in MI .. i would cut a peat media with half wood chips [lots of draining there] ... wet it properly ... insert bulbs... and put it on the north side of the house ... until mid winter.. when i would them bring it into the garage to start tempering it to warmer temps.. and then indoors ... i would probably not water it again ... until AFTER it started growing in spring ...

nothing like a bulb.. forced to bloom in a gray depressing mind numbing MI winter ...

good luck

ken

Here is a link that might be useful: link

It's not really valid to compare bulbs planted in soil that freezes to bulbs planted in containers that freeze solid.

Ground soil temperatures are not uniform. Even though the soil may be frozen solid on the surface, temperatures rise the deeper into the soil profile you go. Unless you are dealing with a permafrost situation. The bulk of the soil mass itself acts as a insulation. That's why the the roots of trees and shrubs can be easily damaged if exposed to cold in a container situation, yet remain undamaged with even colder temperatures if planted in the ground.

It takes far less cold temperatures for the soil in a container to freeze solid. Container soil also lacks the insulating bulk of the soil mass. And yes, the moisture retention of the potting medium does play a role. Since most bulbs reqiure a very well drained soil, it is best to use only a very slightly moistened potting soil and keep the containers out of direct rainfall. Don't even water after planting, as long as the soil is moist. It is the combination of both excess water and too cold tempertures that will cause containerized bulbs to turn to mush.

Most spring bulbs only need a winter chill temperature of about 40F (for a specific length of time) in order to have proper root development and flower production. As long as you keep the containers between about 30 and 40F and out of direct rainfall, you should be OK. An unheated garage is ideal. Or you can sink the pots into the ground (or otherwise provide adequate insulation arround the sides and bottoms) and then cover the tops with a sheet of plywood, etc. to keep the rain out.

Here, I just stored the containers in a covered carport, out of the weather but exposed to winter temperatures. And we can get properly cold here from time to time - into the teens occasionally. But the containers never freeze solid.

It also makes a difference on the size of the container. Smaller ones (less soil) will freeze much easier than larger ones (more soil).