Hi Swan,

I'm new around here but thought I'd jump in...

Is perhaps the soil too acidic? What's planted nearby?

When plants start to die from the bottom up it is an indication the plant is a goner. In some cases intervention (either doing something or ceasing to do something) will allow the plant to recover, but in order to have a reasonable shot at success we have to know what the cause of imminent death is.

I can't determine that from the information in your post. Over watering, underwatering, ph out of whack, pest infestation, fungal attacks either on the plants or their roots and other factors can all result in what you are seeing.

I generally consider coleus fairly hardy (these are in ground grown as opposed to in pots?) so the most likely cause is too much water leading to rot (my guess).

Your friends best bet is to take cuttings off the top. Luckily, Coleus is about the easiest plant to propagate from cuttings. They will root in a few days either in water or in soil.