How to get rid of weeds from garden beds?

[SteveC]

Hi all,

I am starting to renovate my garden beds but have a problem with weeds that have grown in over winter. I sprayed with Roundup a couple of weeks ago but it does not appear to have done anything. Does glyphosate expire?

I have some plants I don't want to remove so ripping everything out and starting again is not an option. The current soil has deteriorated over time, so it can be hard to pull the weeds out unless we have had some heavy rain. The forecast for here is heavy rain tomorrow, so that might help. 

See attached image, in the middle is a hibiscus, with liriope surrounding it. The open area is where the low growing weeds are. It will be a pain to pull them out by hand, but I may have to do it. I have though about using slasher, but I have had limited success with that in the past.

Overall plan is to remove weeds, ad soil conditioner, dig that in then add mulch and new plants.

Suggestions?

Regards,

Steve

[EricL]

Hello @SteveC 

One of the possible reasons that Roundup was ineffective is because it could have possibly rained on the day that you sprayed. Rain effectively washes away Roundup and lessens the effect on the plant. Glyphosate does have a use by date and is often indicated on its container.

I propose trying a strawberry growing trick. I suggest cutting a round circle out of black plastic, the circle should be as big as the area of the weeds but not so big that it will cover the other plants. 

Cut a small circle in the center just big enough for the stem of the hibiscus. Cut a straight channel from the outside of the circle to the inner small circle so that you can slide the black plastic over the ground with the hibiscus in the middle. I then suggest covering the plastic with a few heavy stones or bricks to prevent it from being blown away. The black plastic will prevent sunlight from reaching the weeds and they will die off. Please remember to remove the skirt when you water the hibiscus and to put the skirt back on the following day to prevent weeds from getting sunlight.

After about a week or two the weeds should be well and truly dead, the plastic can then be removed and I suggest putting mulch in the area to control the weeds spread.

Let me call on our experienced members @Noelle and @mich1972 for their recommendations.

If you need further assistance, please let us know. 

Eric

[Noelle]

Hi @SteveC 

When the soil is relatively cold, over the winter months, and sap flow in weeds and other plants is slow, Roundup can take longer to be absorbed and to work than it does in the warmer seasons. For this reason, visible signs of weeds dying could take up to 3 weeks to appear. The small weeds surrounding the hibiscus do seem to be yellow rather than green, so perhaps they are reacting to the weedkiller after all.

Glyphosate in both concentrate and ready-to-use forms will last for several years if stored in a cool location. Usually containers have a 'Date of Manufacture' printed on them, along with a batch code. The chemical is normally good for at least five years or longer from the DOM.

[SteveC]

Thanks Eric,

No rain after use, I watch that carefully.