Gotta hand it to the Ag Talk knowledge base and extremely smart folks that post here.

Here is the previous thread where I asked about the ability to control the flow rate in one direction while being unrestricted in the other direction on a single hydraulic line. 

http://talk.newagtalk.com/forums/thread-view.asp?tid=546528

Here is the follow up after mounting the 1/4" flow control valve

http://talk.newagtalk.com/forums/thread-view.asp?tid=548066

Had a chance today to try it all out so I set up the tripod and the camera to try and capture it on video.  The 1/4" valve seems to be more than sufficient at restricting the flow. I've got it dialed down to the first colored band on the valve so it is not open very far at all. There initially was some concern that the 1/4" one might just be too slow.

Yes the markers ends are in the wrong way but they have to be turned in for clearance to get the planter into storage in this building.

These 3 videos are in windows media format (I converted them from quick time). I'm linking to the small version as they look better instead of being blown up so large. 

At any rate I did not change the rate of drop at all as I have it about where I want it.

http://photos.imageevent.com/vprb/hydraulicmarkerflowcontrol/7200%20Rate%20Of%20Drop.wmv

Here is the valve wide open with no restriction. You can see how violently it comes up and slams against the stop rocking the whole planter.

http://photos.imageevent.com/vprb/hydraulicmarkerflowcontrol/7200%20Unrestricted%20Marker%20Lift.wmv

Here is the valve restricting the flow allowing the markers to come up gently without slamming around. 

http://photos.imageevent.com/vprb/hydraulicmarkerflowcontrol/7200%20Restricted%20Marker%20Lift.wmv

A big thanks to everyone that participated in the threads and linked to these in the Surplus Center catalog. I wish I had asked about these years ago as they are exactly what I was looking for and honestly did not know such a thing existed.

Anyone else that has a similar issues with markers this project is definitely worth the time and effort to install and really not all that expensive.

Hope everyone can view the videos.

If they won't open or play you can get to them in this album (when they open you might need to click on the small or original words underneath for the smaller size. 

http://imageevent.com/vprb/hydraulicmarkerflowcontrol