For best results - and if you are up to the work - I think I would rent a sod stripper for a day and strip off all the surface growth. Then till the area with a focus on where the beds will be. Really helps the future plants to break up that native soil somewhat. Then if weeds still appear to be an issue I'd put down a layer of cardboard and set the frames on it, then fill.

Otherwise, yes several layers of cardboard and then the beds.

Dave

I'm willing to rent a sod stripper. I want this to work well in year one, rather than having substandard results for a few years. Will do newspaper/cardboard over the paths anyway, but like the idea of freshly tilled soil in the beds before I fill them.

There's certainly nothing wrong with building raised beds, but in-ground beds of native soil amended with organic material usually raise enough on their own to drain just fine.

We really like the raised bed look, and this is in a location we'll be looking at almost every day. We're doing native soil veggie beds in other areas of the property.

Unless you've got some really persistent perennial weeds like canada thistle, bindweed, or nutsedge I would just till the grass and soil and build the beds on top. No real reason to remove the grass first. The grass isn't going to regrow up through 11 inches of soil.

Rodney

Now....this is the cheaper option since I already own the tiller......... At least it seems the group understands my dilemma :)

Our "lawn" included at least two types of runner weeds, quack grass and some with pretty purple flowers I call creeping jenny. I would not rototill. We have stripped the sod when I wanted to start a perennial bed but for the vegetable beds I have used the lasagna method. The newspaper disintegrates after a year or two. I have earthworms in abundance and the beds are deep enough that the runner weeds are smothered. Filling a raised bed with a soil mix would be faster but I would consider starting with wet newspapers/cardboard and then a layer of grass clips, shredded leaves or straw (not hay) before filling with soil. I think it's all that good stuff to eat that attracts earthworms and soil microbes. Some gardeners think rototillers hurt the soil. I mostly figure a tiller isn't necessary. I use a spading fork when necessary.

you could also take an old piece of carpet and lay it down to kill the grass. i usually just cut the grass out as i spade, however … it chops off nicely

I have excellent results putting 2x10 frames on top of existing lawn, filling with soil and compost and then planting. No barrier over the existing grass. I've done it this way for many years and have never had grass grow into the bed. I definitely second Dave's advice about the soil stripper if you're doing in-ground beds... ignored his advice on that once and just went at it with my tiller... boy did that one bite me in the backside. Grass for years in that bed. But raised beds over grass I've never had a single issue.

When we have removed sod, it's about 6" thick. Very old "lawn" that may have been pasture at one time.

For those who use newspaper or cardboard under raised beds, is there a concern that the vegetables will not be able to get a sufficient root system developed in the first year before the barrier breaks down? Growing something like tomatoes in 11" of soil seems like not enough room to stretch their roots. Or will the roots be able to pierce through the newspaper or cardboard?

I use both, cardboard mostly in walkways, when used in planting bed It's with transplants. Cut and hole in the cardboard for the plant. I have not had a prob. with overseeding newspaper. Mostly with shallow rooted veg. but also bush beans. I do build the bed up 5 or more inches. Hope this helps.

I'm not sure our lawn was originally seeded as a lawn. If any seed was used, it was probably for pasture or hayfield and I don't think it has ever been fertilized or weed killers applied. Stripped sod goes into a dirt pile to decompose for other projects. But we usually only strip sod for quickly made beds without using the lasagna method and that is usually with a new perennial bed.

Groundskeeper, I haven't had a problem. My best beds were built a year ahead lasagna style to a height of about 24" which settled to about 12" over the winter. Now I maintain them slightly mounded. Winter squash went into my shallow, hastily built bed but I made planting hills with composted manure and fertilizer. We had a good crop. Some tomato plants went into another shallow area and did fine (Opalka paste tomatoes). I suspect roots can pierce the paper even in the first year. I recently cleaned up my pepper patch. Some varieties are very shallow rooted but some grow tall with thick stems and deep roots that had to be dug up with a spading fork.

I've also had no problems adding soil directly on top of grass inside of raised beds. What I usually do is dig up the grass within the pathways, then flip the sod upside down on top of the existing grass inside the bed. The only issue I ever have is some grass wanting to grow along the edges and through the joints of the beds, but I never really worry about it too much, its usually easily pulled or I hit it with the weed wacker. After cutting it back a few times and once you get a good layer of mulch down in the pathways (I use grass clippings, shredded leaves, straw), it smothers out the rest.