This is a bug in IE's flexbox implementation:
In all other browsers that support flexbox, a flex-direction:column based flex container will honor the containers min-height to calculate flex-grow lengths. In IE10 & 11-preview it only seems to work with an explicit height value.
Bug report - (https://connect.microsoft.com/IE/feedback/details/802625/min-height-and-flexbox-flex-direction-column-dont-work-together-in-ie-10-11-preview#tabs)
It appears that this is on Microsoft's radar and will be fixed some point in the future:
Unfortunately, we are not able to address this feedback in our upcoming release. We will consider your feedback for a future release. We will keep this connect feedback bug active to track this request.
Reply from Microsoft - (https://connect.microsoft.com/IE/feedback/details/802625/min-height-and-flexbox-flex-direction-column-dont-work-together-in-ie-10-11-preview#tabs)
For now the simple solution is to use height:
.wrapper {
border: 1px solid grey;
box-sizing: border-box;
display: flex;
flex-direction: column;
height: 300px;
padding: 5px;
}
.element {
border: 1px solid grey;
height: 35px;
margin: 5px;
}
.element:last-child {
margin-top: auto;
}
<div class="wrapper">
<div class="element"></div>
<div class="element"></div>
<div class="element"></div>
<div class="element"></div>
</div>
But this has the limitation that the box wont grow if more .elements are added so probably isn't what you are after.
There does appear to be a somewhat hacky way of achieving this although it does require an extra containing element:
.container {
display: table;
min-height: 300px;
width: 100%;
}
.wrapper {
border: 1px solid grey;
box-sizing: border-box;
display: flex;
flex-direction: column;
height: 100%;
min-height: 300px;
padding: 5px;
}
.element {
border: 1px solid grey;
height: 35px;
margin: 5px;
}
.element:last-child {
margin-top: auto;
}
<div class="container">
<div class="wrapper">
<div class="element"></div>
<div class="element"></div>
<div class="element"></div>
<div class="element"></div>
</div>
</div>
This adds a container (.container), sets it to display: table; and gives it max-height: 300px;. height: 100%; is then added to .wrapper to get it to fit the full height of .container (effectively 300px) thus making IE behave the same as other browsers.
Compliant browsers ignore this and will continue to follow the min-height: 300px; rule set on .wrapper.