Shall I use Roundup - weed killer now or later?

[arouth]

Greetings! What is the best time to use Roundup - now [in middle of April 2005] before the weeds grow or after the weeds have grown? I live in Mississippi. With thanks.

[madgardener]

When the temperatures are consistantly 72o which makes the plants more inclined to absorb the glyphosphates. To make it "stick" better, if you don't have the "rain proof" RoundUp, add a tablespoon of liquid dish detergent (what you use on your sink dishes, not the machine stuff) to the batch you're making up (six ounces to one gallon, no more or much less as it's a measured amount that actually works, since the rule of thumb would be thought to be :"hmmm if six ounces is good, then twelve would be better..." it's the precise amounts that work chemically. No flames please. It's what they taught me in Master Gardening class...I'm NOT a chemist.

On the other hand, you're in Mississippi, it's already into the season there, you should have used pre-emergents early in your season which I would hazard to guess would have been in late February.......(not knowing your growing zone) Preen, and pre-emerging weed killers work when the plants and seeds are germinating early at the end of winter's rest. The RoundUp works when the plants dormancy is over and growth is active, which is why I said it works better when it's consistantly 72o F outside. Hope this helps! (there is a newer batch of RoundUp out that says it works overnight...........not sure, but worth a try, but read the mixing instructions first.

madgardener in zone 7, Sunset zone 36, Eastern Tennessee

[Stephen Henning]

Roundup works best on mature plants. It works by poisoning the roots. So if the sugars aren't flowing to the roots, it won't be as effective. They always recommend using it when the plant is blooming, or at least at the stage in the plants cycle after new growth is slowing and the plant is storing sugars in the roots. It even works in the winter on plants that can photosynthesize in cool temperatures and bright light. The plants that comes to mind are the winter-blooming mints, henbit and stagger weed.

[Warren]

If by "before the weeds grow" you mean before any foliage appears, Round-Up is not a pre-emergent herbicide. It won't stop new weeds from growing. It only kills existing weeds.

Round-Up is absorbed by the foliage, and then attacks the growth systems of the plant. So it also won't work on weeds that are at the end of their growth cycles, or are dormant. Round-Up works best when the weeds are actively growing, or even flowering. And any Round-Up that doesn't stick to the leaves is wasted. It does no good to wet the soil. It also does no good to apply Round-Up, and then mow down the foliage before the weeds completely die back.

[Phisherman]

When plants are actively growing during a sunny day with no rain in the forecast. I use it where it is difficult to hoe, hand pull or use a weed eater. Recently I had to apply Roundup several times (2 weeks apart) to an established poison ivy vine before it bit the dust.

[Marley1372]

the effectiveness of roundup greatly depends on species and growth stage, but it defnitely does NOT work best on mature plants. It works best on plants that are actively growing. You can use roundup at temperatures much lower than the 72 degrees mentioned in a previous post. It will take longer for it to kill the plants, but I assure you it still works. In response to mad gardener, precise amounts do work better, however, with roundup, a stronger soulution DOES make a difference. I use roundup alot in the nursery and usually use a 2% mix. This has little effect on things like nutsedge, horsetail, and many perennial weeds. Upping it to 5 or even 10% makes a huge difference and also makes it work faster.

Toad

[yippie]

I use it to increase the frequency of disease, then I can buy a fungicide to further poison my yard.

[Lar]

In article , [e-mail] says... :) On Sat, 16 Apr 2005 20:53:25 GMT, Phisherman wrote: :) :) >On 16 Apr 2005 09:43:48 -0700, [e-mail] wrote: :) >

:) >>Greetings! What is the best time to use Roundup - now [in middle of :) >>April 2005] before the weeds grow or after the weeds have grown? I live :) >>in Mississippi. With thanks. :) >

:) >When plants are actively growing during a sunny day with no rain in :) >the forecast. I use it where it is difficult to hoe, hand pull or use :) >a weed eater. Recently I had to apply Roundup several times (2 weeks :) >apart) to an established poison ivy vine before it bit the dust. :) :) :) :) I use it to increase the frequency of disease, then I can buy a :) fungicide to further poison my yard. :) There's always the ole 20% vinegar route..ooops never mind it's a class 8 hazardous material.

[bamboo]

The best time to apply is after reading the label.

Dry day, no wind, no rain in the next 24 hours, plants actively growing, outdoor temps closer to room temp.

[Leon Trollski]

Consider why you may have so many weeds. Is it a case of neglect, wrong grass type, wrong soil type?

Weeds are symptomatic of another problem, roundup will solve your issues but non-chemical solutions are better for you, your land and your environment in the long run.

Sorry to sound like an insufferable tree-hugger.