Support or not depends on the weight of the row cover you are using - weights vary greatly. Floating insect barrier types can be laid on the ground and it "floats up as the plants grow.

Heavier weights will require hoops or supports of some kind and air circulation under the cover to avoid trapping heat. How strong the supports need to be will again depend on the weight used.

Do you plan to trellis the cukes and melons or just let them run along the ground?

But please keep in mind that pollination and production will be reduced under row covers unless you plan to hand pollinate regularly. Otherwise remove them once the plants begin to bloom. So how effective row cover will be all depends on the specific "pest" you are protecting them from.

Dave

Thanks Dave. I am getting this cover http://www.amazon.com/gp/aw/d/B000HHQNBG?pc_redir=1400334780&robot_redir=1

It looks lightweight.
I have read about how terrible cucumber beetles are, I figure should try to protect against them. I figure once the plants are bigger (but not flowering yet) I will remove the cover.

I am still figuring out if I will trellis the melons. I am new to both the cucs and the melons.

Yeah that one is primarily a frost protector, note how it says "traps heat and moisture" and "frost protection" on its label? It will need supports and either opened at the ends for cross ventilation or rolled up in the heat of the day once the seedlings germinate.

Linked insect barrier below, it weighs less than 1/2 as much and little to no heat trapping.

Dave

Here is a link that might be useful: Insect barrier row cover

Oh....yes Dave that is what I need! I will get that! Do I need to put that down as soon as I sow the seeds?