I cut down a sumac 2 yrs ago that was almost dead and many new shoots came up. They looked healthy and this year had healthy flowers. Mid July they died and now some of the tops are withered. I don't water much as I didn't think they needed it. Could it be the soil? Not enough phosphorus?
Probably a water issue...not enough. Though drought tolerant, the term is relative depending on the region in question. Staghorn sumac is native to the Northeast and midwest, where a summer drought is characterized as infrequent but very heavy rain (thundershower weather patterns). With such heavy soakings, deep rooted plants can weather 2-4 weeks without rain. Nanaimo has a Mediterranean climate, experiencing very little summer rain in general with less than half the summer precipitation of Kingston for example. I don't imagine there is much deep soil moisture remaining after mid-July?
