Renewing a Thin Hedge

Is there any way to salvage a sickly looking hedge that is bare at the bottom?

Yes you can salvage the hedge with some major pruning and patience. It will take some time to turn these top heavy shrubs into green beauties. A slower but less stressful, on you and the plant, method is to take one third of the older stems back to ground level. Then reduce the height as needed. Repeat this for three years and soon you will have green leaves from bottom to top. Or take the whole planting back to several inches above ground. Most hedging shrubs like privet and alpine currant will tolerate this severe pruning but it is always best to ask before breaking out the shears. Reduce this problem in the future by pruning the top narrower than the bottom. This allows light to reach all parts of the plant. Wait until late winter or early spring to undertake severe pruning.