Weed control for a fall plot?

[Rem 700]

I have a 1/2 acre plot that was in soybeans last year. This plot can flood in the spring so I want to use it for an annual plot and plan to plant brassicas in August. However, I am wondering if there is anything I should do in the Spring/Summer to make it easier for me to drag and plant in August (thinking specifically about weed control). Should I just keep it mowed through the spring/summer? Should I let it go and mow it once before preparing the seed bed in August? Should I spray in the Spring (will that be worth the money invested)?
This is my first year putting in a fall plot. Any advice would be appreciated.
Thanks.

 

[Sligh1]

White clover & alsike clover. If it's weed free right now, I'd frost seed it heavily in Feb or March. Could add some red clover as well. Alsike does well in wet soil. Followed by white. I like frost seeding at very high rates (yes, more than recommnended) & u will have a cheap and great plot if you do that. if it get drown out, you're still not talking even peanuts in cost.

 

[Rem 700]

Thanks Sligh1. That's exactly what I am planning to do in my other 1/2 acre spot that is still in standing beans right now. That field is higher and doesn't flood. I have read mixed reports about frost seeding rates. However, I do plan on almost doubling the seeding rate for my first frost seed. It can't hurt and I was able to pick up some seed this winter that was on clearance but still had not expired on the inoculation date.
Just don't know what I should do with the other field that I won't plant until August (in brassicas).

 

[Swintonator]

My father and I have turnip, clover, alfalfa and a corn/soybean plot every year. This year we decided to try our first brassica plot. We just let it go till the end of June, mowed it down and sprayed it with generic roundup. Worked the ground and planted August 1st. Even with very little rain the plot looked great and had very few weeds.