[joannej]

I used the liquid "acid-loving" Miracle Grow on my bottlebrush trees. Try to buy it at Ace hardware (couldn't find it at Home Depot). They are getting around to blooming now. The yellowing is caused by chlorosis symptoms:

"Symptoms can vary depending on several factors. How alkaline is the soil? The higher the pH, the more chlorotic the plant. How long has the plant been chlorotic? In general, the longer the plant has been chlorotic, the more severe the chlorosis. Generally, mild chlorosis starts as a paling (lighter green to lime-green color) of interveinal (between veins) tissue, whereas a yellow color indicates a more serious condition. In some cases, only part of the plant is chlorotic. Affected areas (or the entire plant) may be stunted or fail to produce flowers and fruit. In addition, chlorotic leaves are more prone to scorching and leaf diseases. With severe chlorosis, the leaf veins will turn yellow, followed by the death of the leaf, the affected branch may die back, and death of the entire plant can occur."