I am battling chufa. It exudes chemicals that make it difficult for other plants to grow. I am trying to crowd it out and make lots and lots of biomass.
Last fall I broadcasted the following: kale, rye, hairy vetch, winter peas, and crimson clover. My garden is on a slight slope. A significant amount of seed was washed downhill in the fall rains, so the upper part of this area is sparse and the bottom is crowded. Also, the soil at the bottom started out better as it has had woodchips breaking down for the last couple years, so taller plants. About 9" at the top, 2 feet at the bottom.
I waited for the fall rains, which of course were 3 weeks late, my kale didn't like the late start. 50 miles west, the rain was on time. Sigh. The kale got about 2 inches tall and hibernated all winter. Come spring, they bolted before getting big enough to harvest any of it!
My spring-sown turnips are finally sprouting in some bare spots. I expect them to go to seed mid-summer.
I will be seeding amongst all this growth in hopes that they'll replace the crop from last fall. Here is my question. Do I need to mow it before I under sow? There will be popcorn, cowpeas, and amaranth.
I personally would mow the tall plants and drop them at the top of the slope. Of course I mow with a scythe so I can be somewhat selective. I try to mow any undesirables before they make seed. and desirable after they make seed but before it is dispersed. Then I move what I cut to where it needs more cover and seed. I have a problem with field daisies so I cut them at the soil level then later when vetch and alfalfa have set seed I cut them and cover that area. with them. My winters are also some times 7a or 7b or 8.