Answer: If you want, you can completely rejuvenate the back lilac bushes on the three year program. Takes awhile, but it's worth it. Just cut out 1/3 of the old branches each summer, for three years....i.e., 1/3 in 2000, 1/3 in 2001, 1/3 in 2002. This completely revitalizes the lilac. Also, try fertilizing them with a blend high in phosphorous and potassium (second two numbers of mix). You can also work some triple superphosphate pellets into the soil at the base of the shrubs. This feeding regimen is good for all of your lilacs. Also, top dress them in the spring and fall with compost or composted cow manure.
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