All weedkillers will kill green leaves on hedge plants

If you want to spray close to a hedge hold a piece of cardboard or hard board between the hedge and the weeds you want to spray. Spray on a windfree day as the sray can easily blow onto things you want to keep.

Roundup is as good a weed killer as any for this sort of job.

If there are weeds between the hedge plants either paint weed killer onto the weeds or use a hoe.

There is a product - Kerb Granules which we were told about, for use around our newly planted trees which we set in grass, to keep the grass/weeds at bay around the base of the trees. Useful for the control of weed growth around trees, shrubs and roses along fence lines, hedge lines.

Only for use around late December though.

You could try watering the glyphosate with a watering can (Home Base sell ones intended for the purpose with a rose that's easy to control). The dilution is different but the instructions are on the packet. It is much easier to avoid getting any drops on the hedge and if you go slowly you can actually use something to protect the bottom of the plants as you go. If your hedge is deciduous you can apply safely before the leaves come out - wetting the bark will not harm the hedge, only the leaves absorb the weedkiller but its probably a bit late in the season to risk that this year. I use this method now having damaged several things in previous year with spray drift - we are hardly ever without a bit of a breeze in our garden and its lethal!

Glyphosate applied in and around woody stems and trunks, on a very still day, should be okay. Choose a 3 and 6" pot, cut the base out, place over the area to be sprayed and spray into the upturned pot. Leave ten seconds before lifting the pot to the next area to be treated. This keeps the spray from spreading out into the open air and nearby plants/leaves etc. The watering-can method may be safer at this time, now leaves are sprouting, and at any other time.

That's clever Avk!