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Organic weed killer?

Posted: Tue Feb 02, 2010 9:24 pm
by kmax1940
Hello, this is my first garden.... I have really bad clay soil so I am going to do a raised bed...

I am trying to prep the soil under where the bed will be..

I tilled up 3 or so inches and removed it... BUT there are still weed roots in some places... I hate to put the bed on top of this because the roots will grow up through it...

Anyone know of a really good organic weed killer?
Or should I just put the bed on top of it?
I can post pictures if that will help.

The beds will be 1 foot tall.


Posted: Tue Feb 02, 2010 9:44 pm
by Toil

Posted: Tue Feb 02, 2010 9:49 pm
by kmax1940
thanks... the bed is only going to be 1 foot deep... so I think the roots of the plants might need to go down beyond the raised bed... and into the soil beneath it...

So it I cover it with cardboard etc... the roots wont be able to get through...

Or... maybe the roots of the plants will only need about 1 foot of depth...
Not sure...

Posted: Tue Feb 02, 2010 10:09 pm
by soil
carboard breaks down, the point is it smothers the roots on the bottom leaving your bed on top weed free( unless your new soil contains weeds. or they come airborne from other locations ) when it decomposes there is far too much soil on top of the weeds down below to grow through. they die and become your new plants food.

Posted: Tue Feb 02, 2010 10:11 pm
by kmax1940
thank you so much! i will seriously look into this..
I only have about a month and half before I plant so I am not sure if there is time for it to break down.... I should have done this months ago and it would be ready....

thanks again for your time!

Posted: Tue Feb 02, 2010 10:25 pm
by lesgold2002
Hi Kenny,

You are doing right to use the raised bed system on clay soil. Most crops will do fine with only 6" depth. One foot is generous indeed. I have used 6" raised beds over 'gumbo clay' here in S.Tx for 20 years now.

The weed roots that concern you will not sprout and grow through the over one foot of soil that you intend to add. But should you decide to use cardboard it will compost away in a week or two and pose no barrier to your plants root system. The clay beneath has many minerals that the crops could make use of. :D

The best organic weed killer is mulch. Also there is little weed problem in fertile soil. So any effort to improve soil fertility will be rewarded with less weeds to fuss over. Bare ground is weed-seed heaven. Always keep some cover on the ground, either mulch or cover crop, and the weed problem will become practically non-existent.

What are you gonna plant?


Posted: Tue Feb 02, 2010 10:29 pm
by kmax1940
wow thanks! that makes me feel much better about this!
so 1 foot is enough!

south texas? we moved here to alabama from austin in 05. :)

going to plant tomatoes, squash, zuccini and peas.... not really sure about what type of peas... snap peas maybe.

trying to start with some easy stuff the first time...

thanks again!

Posted: Tue Feb 02, 2010 10:46 pm
by applestar
I also use the cardboard on clay topped with soil raised bed. It's a good idea to fracture the soil underneath by standing on a garden fork and rocking it back and forth. Also put down something highly nitrogenous like composted manure, rough compost, or alfalfa meal/pellets to help break down the cardboard (especially if you've already removed existing green stuff -- I usually leave grass/weeds under the cardboard) and water the ground and the cardboard well before adding the rest. I wouldn't be planting around here until mid-March at the earliest, but, if you are planting soon and are worried about the cardboard breaking down in time, use 4~5 sheets of newspaper/newsprint/kraftpaper (usually used for packaging) instead, otherwise, your veg roots may hit the cardboard and go into nitrogen deficiency shock.

You know peas (especially if growing snap peas) go in first while it's still kinda cold, right? Then tomatoes after things warm up a bit more (light jacket season). The squash and zukes go in after it's no-jacket warm. You could probably also grow lettuce, arugula, spinach, etc. leafy greens before squash and zukes, and grow bush beans (or the zukes) after peas. :wink:


Posted: Wed Feb 03, 2010 6:58 pm
by GardenGeek
The best option is to use Vinegar for killing weeds. It will kill weeds after few hours from when you spray it. It is so fast in action
Use concentrated vinegar as it seems you have got so many weeds to kill
Be careful with it because vinegar can kill grass in less than 3 hours. So spray it right where you want the action

Posted: Thu Feb 04, 2010 2:30 am
by gixxerific
You have come to the right place. What everyone said is good, if it were me I would do as Applestar said and use newspaper instead of cardboard since it's getting so close to crunch time. But you shouldn't have a problem. Don't forget to mulch it after planting. You may have a few weeds but that won't kill the garden it may even be good for it but that's a whole 'nother thread altogether.

Welcome, stick around you will learn a lot more tricks of the trade. :D

Posted: Thu Feb 04, 2010 9:01 pm
by GardenGeek
Although after reading previous post, i am not in much favor of killing these weeds as they are helping your soil a lot. But still if they are disturbing you to o much raising your bed. You can use boiling water at its root to get rid of these weeds naturally.
That is the best way which will never affect any other plant nor the nutrition of soi :( :lol:

Posted: Fri Feb 05, 2010 2:39 am
by gixxerific
Correct me if I'm wrong but the boiling water will kill some of the beneficial microbiological life that is in the soil thus causing harm. Also I'm not 100% on this but if a foot of soil is being placed on top of the virgin soil. What ever those weeds might have been doing will be somewhat lost anyways. In theory if the soil is in bad shape they will come back. Hopefully the soil (hopefully with compost) that is being added should be in better shape than the previous soil. Does this make sense, I hope, so I'm very tired right now.