How do you kill a lawn before placing sod?
Im going to be doing some lawn replacement in the front yard of my house. And its being reccomended that I kill the existing lawn first chemically before placing the new lawn down because it is loaded with weeds and don’t want the weeds to invade the new lawn.
The question I have is that if I kill the existing grass, won’t the chemicals stay in the ground and then kill the new lawn?
July 28th, 2010 at 12:06 am
I have recently done this and your question is a fair one. The most common weedkiller is called glyphosate, or roundup, or zero.
First, it is for use on broad leaf and most common weeds. It is fairly inert and breaks down rapidly in normal conditions in the environment, This is why it is favoured in agriculture as you can resow in as little as three weeks or even run stock over the next day.
Keep in mind a) buy the dearest or most concentrated type (read the pack). b) spray while plants/ weeds are actively growing, will not kill seeds or anything dormant. c) apply per instructions, do not mix stronger or mix with other chems. d) allow three weeks for everything to be dead. Do not mow, do not dig, do not even water until then.
This will work but there are still weeds that live in the soil and come up when the season is right. These will remain there even after spraying etc.
When professionals do this sort of work they will recommend actually ‘gassing’ the soil to kill absolutely everything. This is extremely expensive.
My approach, if it were my lawn, would be to wait till the warmer months and ‘solarise’ the soil. This is done by laying out black plastic over the old lawn, making sure there are absolutely no gaps and pinning it down. Leave it about 6-8 weeks like this and nothing living will be left. The heat generated by the decaying old lawn and the sun on the plastic will basically cook even onion grass seeds etc.
Lastly, if you have someone in to mow your new lawn, make sure they take precautions such as washing out their mower/ boots etc. so they dont bring further weeds in. Keep up proper maintenance nad you will have a fantastic, healthy, and weed free lawn.
July 28th, 2010 at 12:44 am
I agree with Cameron. Solarizing the soil is the best solution. By using a chemical to broadcast kill the grass you are damaging the soil and your new sod will pay for it dearly over the first 3 – 5 years. The sod company will not tell you this because they only understand the immediate.
A healthy lawn needs a strong balance of microbes and live biology to thrive. If the ground is thoroughly tilled up it will disrupt the weeds and the new sod that is laid on top will choke out 90%.
You will always get weeds in your lawn so killing off everything at the beginning is only a short term solution with long term detrimental effects.