I've searched around and can't seem to find an answer to my question and am hoping an expert could better assist.

In summary: I'm looking to extend an existing garden space - The area I'm expanding into is all grass - The soil in our area has very high clay composition. Do I till now, later, or not at all and just smother it with dirt? Can I still do the cover and mulch method still or is it way too late to actually kill the grass?

I'll be adding additional compost blend dirt as well as chicken manure and decomposing bedding to the old and new garden and soil testing will be done. My thought is that tilling the grass to get a grass/dirt blend that can decompose more before planting would be beneficial - I could then cover it with tarps to assure the grass dies off.

I meant to over the grass in the fall to prepare for this year but I didn't and here we are. The area that will be expanded into is going to be dedicated to WARM season plants (melons, peppers, etc.) so I won't be transplanting for almost 2 months (based on the almanc chart).

My understanding is not to till old (gardened in) soil until you're practically ready to plant. For the existing space, I plan to add the compost and broken down chicken manure, as well as new soil, then till it all together the day before planting.

I understand the importance of soil health, pollinators, etc. - The soil will be tested and properly amended - My main question is how to expand the garden, with the grass already existing, at THIS time in the year (3/22)? My thought is to till it today, cover it with a tarp to kill the grass, then when it comes time to plant I'll remove the tarp, add a compost soil blend & manure, then till it all together before planting.

Thank you!

Hi fellow Michigander! When we extended out bed we tilled the grass at this time of year. We didn't tarp it though and that might have been a mistake. Even with mulching we did have some grass grow back. If you are going to wait a couple of months to plant I would go ahead and till and tarp now. 2 months should be plenty of time to kill off the grass before you plant.

Tilling in the fall works also. You just got to re-till the spot in the spring. You'll have less grass/weed remains laying around after you till.

seilMI said:Hi fellow Michigander! When we extended out bed we tilled the grass at this time of year. We didn't tarp it though and that might have been a mistake. Even with mulching we did have some grass grow back. If you are going to wait a couple of months to plant I would go ahead and till and tarp now. 2 months should be plenty of time to kill off the grass before you plant.

Thank you! That's what I figured but thought I'd ask - My main concern is creating some good soil for the future, that is still plantable for this year - If the biggest concern will be a bit of grass re-growing, it won't be the end of the world.

It's between that and doing what I did last year - Bulldozing all the grass up (removing it entirely) then putting compost-blend over it - That wasn't very successful as it took out all the "dirt" the grass was rooted in. Hoping that tilling the grass and blending it with the dirt, then adding compost/dirt blend over it will be successful.

when I did mine, I tilled half, then later added another area that I didn't till. Real sorry I didn't till that. The tilled side drains better, the weeds are so much easier to pull.

It depends on just how deep you till. If you till to 2-3", you produce a certain set of results. However if you till to 6" deep, you get a different set of results.
I am not that far away from you in Livonia, but I would till now, 6" deep. Add whatever I needed to in order to improve the soil. Then I would let it sit 2 weeks intil roughly April 10th. Then I would till again to 6". And I would till in multiple directions each time. East to West, and North to South.
With the second tilling, I would again add to the soil. Let it sit until about the last week of April when you could start planting, cool stuff first. Then do warm loving stuff by Mother's Day.

If the soil is largely clay, I would think that tilling to 6" twice will make a big difference! Good luck!!!

Unless you till in leaves, which around here means you get a very globby soil at planting time, you should have no problems.
Tilling deep as Bill said is best.

We don't till at all just roundup, put down fertilizer and plant seeds. But we also do it in the late fall out here in the PNW.
If your need adjustment or soil isn't level you need to do it before you plant the seeds.

If you till, one needs to know where the underground lines and pipes are so call before you till.

I guess it depends on your soil? Around here the dirt is so hard lots of clay. Adding compost is a need. I like to top w straw for a few years to help the soil out, price of straw is crazy the past few years though. Be sure do not make a newbie mistake and get hay, not the same thing, hay full of seeds

Frillylily, that is a great point. We also have clay and it's needs to be watered to not be so hard. Putting down seeds
now will mean you will have to watch it carefully when the summer months hit.

It very much depends on what sort of grasses you have growing in the area. Some kinds will just be slowed down somewhat by tilling.
Grasses that spread via underground rhizomes (e.g. the ubiquitous "quackgrass" we have here in the PNW) will actually be back stronger than ever, as each little piece of tilled-in rhizone will survive and be a focus of infection. It takes a couple years of complete elimination of sunlight and water to get rid of that stuff.

You might be able to rent a sod cutter (or hire a landscaper who has one) and get the job done in a trice. You then can till the resulting bare spot and add your desired amendments.

You have gotten some great advice from folks in your area. One thing I'd think about is keeping the new bed covered in horticultural plastic all summer-- you just make slits for your plants. Squash, tomatoes, cukes...love this. Keeping the new bed covered with deprive the grasses of sun -- you will starve them out. You can cover the plastic with pine shavings (get bales at a farm supply store) for looks if you'd like. Don't use straw -- you will introduce seeds. Johnny's Seeds, Jungs -- all carry the plastic. They even have a heavy paper for mulching -- it works great, but be careful about walking on it.