Hello ESMclane. Ken here in the Chicago area. Arborvitae are very adaptable
to many different soil types from acid to alkaline. They can grow alongside
rhododendrons and azaleas in an acid environment and also grow in the alkaline
soils of the upper Midwest. Fish emulsion is usually a 5-1-1. This would be fine for
now. But the Miracle-Gro would be a good choice too because it is more balanced –
more phosphorus and potassium. Ron Smith, Extension Horticulturist with North
Dakota State University, says “arborvitae growth and vigor will be aided by using
Miracle-Gro annually. Just don’t use fertilizer spikes.â€