New garden bed

Can I mix grass killed a month ago with roundup into soil With tiller. What to do with fresh sawdust, I have a lot, if it can not be used fresh how do you rot it quickest. If the new bed has 6" of green grass on it do I mow it first and remove or just run the cultivator tiller over the lot (and the aforementioned roundupped dead grass from elsewhere.Or roundup the new bed, wait a week or two then cultivate ? Now there is a muddled bunch of questions.
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You'll get mixed (and passioned) answers there.
You can do so, in the sense that the residue in the soil will not act as RoundUp does on your future plantings. RoundUp is absorbed by the leaves, not the roots.
There is lots of discussion of the safety of that in-soil residue. I can't address that, except to share my perspective that the available data is for agricultural levels of use, not gardener levels of use.

I've put it in the compost pile, but I don't have large amounts.
Whether it is good to mix in fresh will depend a lot on what sort of wood it was from. It is certainly good for breaking up clay, but may skew your nitrogen needs.

As I recall, the RoundUp label has instructions for most of that. It is absorbed by the leaves, so you don't want to mow before spraying (more leaf area is better). I forget the time suggestion, which is given assuming you are killing an old lawn and planting a new one. I assume that the same time should hold for planting a garden.
My tilling experience is limited, and I've never tilled tall grass, so I have no advice there.

FYI, both "RoundUp" and "tiller" are holy war issues for some who wander in and out of this group. If any response seems surprisingly harsh, that could be why.
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F Murtz wrote:

yes, but why?

depends upon where the sawdust comes from...
use it as a light mulch after planting, it won't rot as fast on the surface, but that's ok, you don't really want it to rot fast anyways (or see below).

cover it with a few layers of cardboard and then put the sawdust on top of that to hold it down. in a few months the grass will be dead. don't need to dig it up or till it or remove it or disturb the rest of the soil. eventually the worms will break down the cardboard. to plant, put holes through where you need to put seeds or plants and then have at it.
the more you disturb the soil the more you will move weed/grass/etc seeds around (and into the germination zone).

good luck,
songbird
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songbird wrote:

Just because I have some and I thought dead vegitation may be good for soil.

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F Murtz wrote:

if this is from a weedy lawn or grass that has gone to seed then it's well worth avoiding.
the first season in a new garden bed the soil may already have plenty of nutrients (but it would help to know what was grown there before, what has been added to the soil and if any tests have been made).
also, if you are planning on planting anytime soon it is usually not a great idea to incorporate too much uncomposted material into the soil (use it as a top-mulch instead). if it isn't thick enough to block the light you can plant right through it without tilling.
songbird
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