Short cover crop to control grasses in temperate climate

Hello Permies,

I would like to find a short-sized cover crop that would overcome Poaceae (grasses) on fields in a temperate climate (Cfb close to the west coast, south of France).
The grass fields are typically mowed or reaped around here, and when I get on this type of field and am asked to install a system (a food forest for example) I need to take control over the grasses.
I am thinking first a winter annual plant, that grows faster than the grasses, and then the perenial cover crop.
I need the final cover crop to be short sized so that I can plant productive plants (lower layers in a forest or orchad) and avoid competition.

Can you advise me on what plants would work?

In particular, I am working now on site where the soil is mostly sand.  But I could be also clay-loam soils.

I'm musing here, because I do not know the are to give specific advise, but I wonder if perhaps you are working in the wrong order?

You mention food forest and orchards, and my first thought is to get the trees planted in their locations. You will dig them in, removing the grasses localized to the dig site and then mulch to help prevent the grass encroaching on the trees. When trees establish, their roots can provide them the nutrients and water that they need without worry of competition. Once the trees are in providing shade and putting pressure on the grasses, you can then incorporate an orchard cover crop mix that works to benefit your trees.

Could you give more ideas of what you want the cover crops to accomplish? I'm trying to figure out the balance of effort and reward as I am a lazy gardener personally.

I like Timothy's suggestion about planting trees first.

There are a lot of plants that can help choke out grasses and weed.  

My favorite cover crop is winter rye though I am not sure that would be what you are looking for.

I have read that alfalfa is good for choking out weeds and grass because alfalfa uses lots of moisture and nutrients.  Still, I feel this is not what you are looking for.

Creeping thyme would be a good choice if you plant around the trees for your food forest.

This thread offers some suggestions:

https://permies.com/t/181179/Ground-cover-layer-plants

Hi Louis, I'm liking the thread that Anne suggested - there are some good ideas on there. It depends a bit on how much maintenance you can do - time and effort on encouraging the new forest plantings.
I certainly haven't found the secret as yet to making it effortless, but just cutting the grass and using it to mulch around the plants I want works to a reasonable extent.
I think if I were starting over I would turn over the turf and try and relieve the compaction there is in my field - which would also add some organic material under the soil. Then I would plant a cover crop like fodder radish that has deep tap roots and gives good coverage, or possibly swede (rutabaga) which I've found gives very good coverage (swamping my carrots and parsnip in the same area!), around the newly planted trees. I find the fodder radish will go to seed and propagate itself, too early to tell as yet with the swede. Wild cabbage gives very good coverage for me as well, at least on already cleared ground, but may be too tall for your requirements. None of these are perennials, although some of my wild cabbage is three years old now despite flowering.
It would be interesting to just scatter useful perennial seeds and let them fight it out and find the places where they wanted to grow. You'd need a lot of seeds though.

Hi,

thanks a lot for your responses.
Indeed, I am planting a food forest and an orchad, but there will be open areas where I need to controle the ground cover. So there are two types of areas :
- the area around the newly planted trees, or maybe around the mulching and carboarding immediately place around the tree,
- and on the other side, there are the open areas.

So in the forested/orchad areas, I am planting trees first for sure, but I still need a bit of control on the ground cover during the time the trees grow.
And in the open areas, I need to find something useful (maybe nitrogen fixer or edible) that can replace the Poaceae. Ideally, an annual that grows fast and dominates the Poaceae, and then a perenial that stays in place for years.

I read the other thread you suggested, here are the ideas I've collected for now:

Annual:
- winter rye (Secale cereale)
- winter vetch (Vicia villosa)
- Nasturtium (Tropaeolum majus)

Perenial:
- Sweet potatoes (Ipomea batatas)
- Viola sororia
- comfrey
- Thymus serpyllum et thymus praecox
- strawberry or wild strawberry
- white clover (Trifolium repens)