You can try dosing it with a liquid iron chelate. That has a remarkable ability to "green up" just about any broadleaved evergreen shrub. And chelated iron is not really a fertilizer.......more like a plant tonic ;-)

just a caveat ..... when spraying anything on a plant ... do not spray in sunshine ... or high heat .... dont slather a goo on a stressed leaf ....

and in my experience.. dilute it half of a suggested amount ... you can always go back and spray again ... but if you burn all the leaves off.. for whatever reason ... perhaps because you think.. that twice as much.. might be twice as good ... well ... thats not good ... especially when you are doing a favor to a friend ....

gal ... since the iron is not a fert.. and presumably this is an evergreen box ... is there a proper season or timing for spraying ?

just noticed no location ... where are these plants???

ken

That's nicely done. how often do they trim it?

No specific timing necessary, although the effect is more rapid and noticeable during the active growing season. This more of a liquid soil amendment - applied to the soil only, not the foliage.

Paling or lack of color on the foliage of most broadleaved evergreen plants (and yes, ken, boxwood IS evergreen!!) is often due to lack of adequate iron in the soil or the inability to access the iron that is present because of the soil pH.

I am assuming the OP is in CA, since this was cross posted to the California Gardening forum.

Various existing blights as well as nematodes already affect box in California. Random dead sections like that shown on this thread are also common in my area. If you want to be sure you are making the best response to this damage you should take samples to your nearest USDA Cooperative Extension Service branch office and see if they can tell you what the exact problem is.

Also California Extension has a particular interest in incidences of blight like conditions being seen on box in California because the new to North America and particularly destructive Box Blight is being monitored by them.

Thanks for the advice everyone. I'll try some iron and maybe have the soil tested. There was another chunk in the front that had died and we took it out and replaced it with two new boxwoods.

Matt- the gardener comes every week and they trim it fairly often.

I am indeed in California and I am posting this reply under my old school gardenweb account so I have a jayferg account and my Facebook /houzz account is jayferg1 but my computer won't sign me in through their link so I never know which account I am posting from!