To Mow, or not to mow

Hey everyone, have 5 acres im prepping for a homestead right now and I plan to put sheep on it as well.  I recently had to root rake the 5 acres to remove cacti, which did a phenomenal job, but I'm trying to get a healthy pasture now.  I reseeded the area that got hit the hardest, but much of the 5 acres recovered very quickly and is now knee high in length.
My father who is assisting me with this and is a much more experienced gardener believes we should let everything grow to seed and not mow.  We did a cover crop pasture mix our local seed shop sold.  I think we should mow to prevent the taller plants blocking out the sun.  
What do you guys recommend.  I'm attaching a picture of the plants I'm most concerned with choking out the sun, as I don't think hair sheep will eat them, they have very thick stems.  If they will, I might as well leave them, but I'm not sure.
We don't plan to put sheep on till 2019 so if letting everything get overgrown and come back in the spring is best, that would be the least amount of work.

Hi Carson!

Can you tell us your approximate location on the globe? Knowing that may help us offer the best advice. I’ll offer my thoughts on your grasses and land. I’m in a somewhat similar situation as my wife and I just bought some land last year that had cows on it for 20 years, but the cows had free reign over the land and no rotational grazing was done, so the cows eat their favorite things and what they find less palatable grows unchecked. My neighbor who owned the cows did mow once or twice a year to keep things like saplings and wild blackberries and other briars from getting a foothold. There are now no grazing animals on my new farm, but I want to put cows back on in two or three years. After I did a soil test and limed the land I’m letting everything there grow and I’m making observations on what’s growing. I have some different cool season grasses, some desirable forbs like clovers and vetch, and also some undesirable weeds like thistle. Come August I'll be making notes of how the pastures have changes and what kinds of warm season grasses are growing and what kinds of weeds are present during that time.

My plan right now this spring is I’m letting all the cool season grasses and clovers go to seed, which they have already done, and then mow the place in the next few weeks or up to mid June. I’ve been manually knocking back the thistles, to keep them from going to flower. It a slight chore, but there are only a few hundred thistles scattered about, not thousands, so it’s manageable but just takes time. If those go unchecked I will have thousands of thistles, and that’s exactly what I don’t want.

I think the trick to mowing is timing. Letting everything go to seed may mean some undesirable weeds keep proliferating. Try to identify what sort of other plants are growing besides grasses/fescues, and find out if some of those are invasive and will make problems worse if they’re allowed to go to seed, or if some are undesireable as forage for grazing livestock.

If your land were mine, I would err on the side of caution and mow to keep things in check. Mowing is not going to hurt the grasses, they’re prolific and relentless. And one more note, if you haven’t done a soil test, I recommend sending some soil samples to a lab for analysis. Something as simple as adjusting the soils pH with lime can really help encourage grasses and a lot of weeds that love acidic soils can find the less acidic conditions undesirable.

I'm in central North Texas. I believe zone 7or 8. Soil test indicated poor npk and high pH, so ive already fertilized and added some sulfur to assist.  Hoping sheep and chickens will improve it as well

My personal opinion (take it for what it's worth) is i too would mow this season.  You might end up with some unpleasnts that are harder to get rid of.  Like James said, the grasses will come back and it won't hurt them.

james - you mention that you are already out bashing thistles by hand, and that there are only a few hundred.

You might consider getting something like this:



I have used it to remove thistles in a large pasture and it works like a dream, grabbing whole roots.

Those weeds and the best thing you can have to break up your soil and get organic matter in the ground. But i can hear you when you are worried about them taking a foothold. Observation is best.
I would watch the weedy spots and mow just before they go to seed. In other parts of the pasture maybe there isnt so many weeds so i would just leave it.
You have to remember that the taller the forage is the longer the roots and thats where you build soil.

Helen Atthowe talked about the potential benefit of letting your cover crops go to seed at the Garden Master Course, with comparative case studies.  Here's the excerpt:

https://youtu.be/3vic6FtDOCI