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Reusing yard dirt for raised planter beds?

Palm Bay, FL(Zone 9b)


I used to be just a container gardener, but after a year of living in my first owned home - I'm ready to start putting in more garden "features". Based on my experiences over the past year - I need some advice. Last year, I dug out some grassy areas to casually install some pavers, (which I just put containers on top of) and wound up with lots of excess dirt that I didn't know what to do with. I ended up "hiding" it in inconspicuous places.

This year, I have another (much larger area) that I want to dig out to install gravel and pavers - to be used for container display, seating, etc. I'm also planning to install raised gardens in the area I prepared for the casual pavers last year.

Since I know I'm going to have a LOT of yard soil that I'm going to remove from the new area, I'd like to use the soil to start filling the raised beds. What I'm concerned about is, all the bits of lawn/weeds/junk in the soil I will be moving. I'm pretty fastidious about removing obvious junk I see - but I was wondering if there was anything I could do about the stuff I miss or can't see.

I am open to recommendations that don't allow me to use the raised beds right away. I am such a container-lover, that I am perfectly happy to fill the raised beds with the soil I want to reuse, treat the soil, and then cover them up with more wood so I can display potted plants on the platform until the beds underneath are ready for planting.



Prairieville, LA(Zone 9a)

Hi Rose. I would remove as much of the grass and weeds as possible from the soil. After putting the soil into the raised bed, you can use a pre-emergent like Amaze or Preen and plant established plants, or put the soil in the bed, cover with black plastic and let it cook in the sun for a few weeks. If you use the pre-emergent, you can not seed the soil as the pre-emergent will prevent seeds from sprouting.

Hope that helps.

Ayrshire Scotland, United Kingdom

I would not use any stuff, chemical or otherwise in your new raised beds, do as themoon suggests and fill the raised area with the dug out turf / grass, as you place waist /Grass etc in the new beds, make sure you lay it up-side-down, that is green grass down and root / soil showing uppermost,
By hiding the green grass you will be preventing the light etc from helping it grow further, and the roots will die down due to lack of damp and soil, we always do this with waste turf or old dug out beds soil, as previously said, remove perennial weeds if any then lay a cover over the now stored turf, don't use clear plastic as it will allow light in but Black plastic, old carpet or even old newspaper does so long as the paper is laid thickly,
Leave alone for several months, have a look and see if it's beginning to go crumbley when you dig it with the garden fork, if not, recover again,
Once all the green has died down then leave this as bottom soil and add whatever else compost wise you want to enrich the soil with, however if you just wish to set pots and containers out on top of this area, then lay a barrier between the soil and wood top dressing and set out your display of pots,
Hope this helps a bit. good luck, WeeNel.

Palm Bay, FL(Zone 9b)

Thanks for the tips so far!

WeeNel, As I am planning to pick out as much obvious grass/weeds/roots/junk from the dug up dirt, I guess what I'm mainly concerned about are the itty-bitty bits of junk that will probably sprout back. Stuff like bits of dollar weed, clover, and other weeds with "tag-along" seeds that sprout back easier than anything. My house is adjacent to a canal that is only mowed twice a year, so there's tons of weeds with "stickers" on them that I've probably been spreading around with my cleanup efforts. I've also been at war with a load of old Virginia Creeper vines that were starting to smother the trees in the area I want to clean out. Some of those darn Creeper roots are 2" thick and over 10 feet long under the dirt! A lot of the roots will be in the area where I will be removing the dirt to install pavers/gravel, and the excess dirt will be going into the raised beds. Last thing I want to do is contaminate the new beds with all the junk I've been busting my ass to eradicate.

Moonhowl, thanks for the tip about pre-emergent weed control products! I wasn't aware of such a thing!

I think I may go ahead on my project with a combination of Preen's organic vegetable garden pre-emergent and the newspaper/plastic smothering technique you and WeeNel suggest. Maybe it's overkill? But I'm a big fan of doing it right the first time... which is why I come to DG to ask for help from all you lovely folks!

Anyone else still want to chime in?


Prairieville, LA(Zone 9a)

I do not think it is overkill....just good preventive measures given what you are working with. WeeNel's suggestion of using the raised beds to hold containers is quite good. You can play with container plants and get an idea how each bed will look when ready to be planted.....and you'll have the plants on hand. While the newspaper works, I always add black plastic over the paper when my goal is to get rid of weeds....the plastic increases the soil temperature and heat sterilizes/kills weed seeds... Best of luck to you Rose.

Contra Costa County, CA(Zone 9b)

Clear plastic will heat the soil hotter than black plastic.
Google 'Solarize' for proof.

If you have time to do a 2-part treatment, here is what I would do:
1) Solarize the location from now until you are about ready to move dirt.
2) Move the dirt, and chop up the soil/root mass the best you can, set it in the raised beds, and use a rototiller, then soak it well.
Cover with clear plastic and seal the edges. Allow it to cook through one summer if there were some really nasty weeds, or at least a month if there were some weeds, but not really that bad.

Part of step 2: If you will be planting directly in these beds I would add compost as you move the dirt. Roughly 1 part compost to 2 parts soil is a reasonable ratio. The little bits of grass, roots and dead weeds all count as compost. Especially after they have been solarized.

Mumble-mulmby years ago I solarized some areas of a field for a project, and as much as 2 years later (after the project was done) aerial views of that field still showed areas that grew differently. Solarizing, done right can kill most weeds and plant diseases.

Palm Bay, FL(Zone 9b)

I do have some time... I come up with ideas faster that ways to pay for them! I do have both black and clear heavy duty plastic sheeting around already, so I can get started trying to smother or solarize the location while I finish planning and executing the framework for the raised beds. My raised beds design is a little more complicated than just build-a-box-and-fill-it.

So Diana, after Googling solarization, I came up with a pile more questions! I think the one that might stop me from using solarization instead of smothering right off the bat right now is that it's January. I do live in central Florida, and yes, it has been unseasonably warm (80+!) for the past couple weeks - but the forecast is still a fairly mild 71 high and 50 low for awhile. I don't believe it's going to be hot enough for the plastic to do what it's supposed to for a few more months, and by the time June comes around, I would like most of the really hard labor done already.

The other thing that is sort of stopping me from wanting to do the solarization thing before digging up the location is - there are some ligustrum trees around the perimeter of the yard that I do NOT want to kill, and I'm sure their roots have to be going under the area I want to "excavate". These ligustrum were nearly killed by crowding of creeper vines and brazilian peppers - and I've had to prune them back drastically already. Since I only plan to dig about 4"-6" down, I don't think my "excavation" efforts will bother what tree roots I may encounter... but I'm concerned that the solarization process will.

I like the idea of smothering or "baking" the ground to kill the groundcover and pests that may be in the yard. I had a bout of nerve troubles in my back last year that I'm still sort of recovering from, so the idea of using a shovel to remove all the live grass/weeds/dirt by hand is not exactly brilliant on my part. I really need to go to the hardware store and see what kind of machines I can rent so I don't hurt myself...

Palm Bay, FL(Zone 9b)

So here's a picture of the area I want to "excavate" for the stone/gravel. The crudely drawn red line is about how far I want to remove the grass, and I plan on leaving pockets near the fence to accomodate the trees, and maybe line the fence with the bromeliads I had to remove to get at the horrid creeper vine roots.

Thumbnail by Plants4myPots
Palm Bay, FL(Zone 9b)

I really am serious about making this area look nice. Here's a before & after composite of all the work I've been doing for the last six weeks... It looks like I was ruthless, and I had to be! Most of the stuff that looks like "trees" that I removed was all Brazilian Pepper and Virginia Creeper.

This message was edited Jan 15, 2013 8:45 AM

Thumbnail by Plants4myPots
Prairieville, LA(Zone 9a)

I agree that clear plastic allows the soil to heat faster, and is great for quick results. The choice for black plastic prevents light from reaching the soil so nothing sprouts and works quite well over a period of time, especially if you are adding manure or composted plant matter to the soil while it cooks.

I must admit, my initial response was based on "build and fill" beds. My error. You should not place plastic over the tree roots....they need rainfall and air in order to survive, and most feeder roots for trees/shrubs are in the top 8 to 18 inches of the soil. I would suggest instead using a good "weed block" material covered with a 3 to 4 inch layer of mulch. That allows water and air to filter through to the roots but blocks the sunlight necessary for weed growth. Do remember that adding stone or gravel will change the pH of the soil to a more alkaline level, so make sure that the trees/bromeliads can handle alkaline soil.

For the grassy area, you could actually just cover the grass with a thick layer of newspaper or cardboard weighted in place. The lack of sun and water will kill the grass and its roots.

Contra Costa County, CA(Zone 9b)

I think most Ligustrum are tough enough to handle the gentle warming that will happen when you solarize at this time of year. I would just hope that it gets hot enough to kill the weeds! Might not, though. Might just get warm enough to encourage them to grow :-( Just like putting them in a nice greenhouse.

Probably covering them to exclude light is the better answer at this time. Thick mulch, black plastic (temporary), many thicknesses of newspaper...

Looking at the picture, I would spray them with Round up. It breaks down pretty fast, and the weeds could be composted.

As for the machine to do the hard work... isn't that why teenagers were invented?

Palm Bay, FL(Zone 9b)

Thanks for the advice!

I used some sticks to really mark out the "line", and I'm trying out the cardboard and black plastic on the edge furthest from the treeline to see how it does. I only had enough cardboard and landscaping fabric pegs on hand to do two patches that are about 9' squares. I don't get the newspaper, which maybe I should - just because sometimes you need a pile of waste paper, I guess. I'd rather keep collecting the boxes that reams of paper come in at work... :) Hey, I do have a box full of junk mail I've been collecting. I bet I could do another patch or two with that!

We'll see how it goes! I bet my lawn mower guy loves/hates coming to my house. I've almost always got a new little obstacle for him.

Diana... teenagers?! I haven't got any of those, they're pretty expensive to make yourself - and there aren't many in my neighborhood to hire. But I do have a 2 year old niece and a 7 month old nephew. So there will be a couple around I can wrangle in a dozen years or so. Til then, my niece could be of some help picking out weeds and roots in the dirt I dig up. :)

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