The main thing with Round-up is the drift from the spray. Spray only when there is no wind. Keep your spray close to the ground.

I have killed Bermuda grass by using Glyphosate (Round Up)but I had to really drench the grass. Paul is right, if your spray is blown into the garden, plants will die.

I only spray at dawn when the air is calm.

Would you consider applying it (straight or slightly diluted) with a large paintbrush (or roll)? I have a flowerbed under hickory trees, and every year I have to kill a number of hickory seedlings (which are too deep rooted to pull). I use a small paintbrush and paint individual leaves with undiluted RU. I have had an occasional stray drop, but basically the method is safe to plants which are inches away.

I have a 2 acre veggie garden, and the weeds are too much for the 2 of us without some chemical assistance.

We regularly use RU and cover small plants with buckets to get as close to them as possible. RU does not translocate, so the only way to damage a plant is if you get it directly on the leaves.

We do use hand-pulling when ever possible, but this time of year when you are trying to transplant hundreds of plants after work and on weekends the weeds start to get away from you.

The paint brush trick works well but I prefer the foam brushes (less dripping). the other thing I have done is buy a "spray shield". You find it in the paint department. It is used by painters who use sprayers to control overspray. The one I just bought at Lowes ($11) is 2 feet long by 10 inches wide with an 18 inch handle. I mark one side with a sharpie so I know which is the "contaminated" side. With this shield I am able to get a lot closer to my beds and protect my plants.

And as the others said, only on a calm day.

any opinions out there about spraying in the heat of the day vs later?

And what about using it at a stronger less diluted strength? any benefit? quicker response? or just more $$$ and not really necessary.

We have a 2' path around our two vegetable gardens and the asparagus bed. Our gardens are surrounded by bermuda grass, and we use the paths as a buffer zone, kept free of grass with Round-Up. I spray very close to the ground with a fan shape on our pump sprayer head, spray only when there is no wind and when the temps are above 75 (which in Texas is about anytime you want to spray!). We use the recommended dosage for Round-Up, not a concentrated dosage, and it works fine for us.
For photos of our vegetable gardens, go to www.rgf-tx.com and see our Red Gate Farm with the gardens.

Stronger rates than stated on the label aren't more effective.

Stronger rates often damage the leaves and thus aren't even taken in to the plant.

When you apply a more concentrated mix, you would apply less of the total mix of herbicide and carrier (water), but the same amount of the active ingredient. The benefit of this is that you don't have to get as much mix on the plant to get the desired results.

So, if you are spraying from a pressure sprayer, the regular mix works great and you use enough carrier to cover the plant. If you want to use a paintbrush, glove, or something else that allows you to apply precisely and to a small area, then you use a more concentrated solution so that you don't have to coat the entire plant to get enough of the active ingredient on.

Lots of good tips already in this thread.

i find the bucket trick works well. You can also use an old piece of cardboard as a shield. i like the pieces they use to separate layers of product on the pallets at Costco, cut in half. Just lay them in pathways when you're done (and they are dry).

Round-up is effective at even lower rates than the label suggests, especially on young and/or nonwoody plants. Using a little sticker/spreader (surfactant) really increases the efficacy even at lower concentrations. Works best on plants that are actively growing so ideally you could spray on a calm sunny day right after a nice rain.

Read labels-if glycophosate is not branded Round-up it's a little cheaper.