If your dwarf lilacs are growing well, they may need no additional fertilizer, especially if they are growing near a lawn that gets fertilized. However, most plants will benefit from addition of compost as a mulch. As the compost breaks down, it adds organic matter to the soil and provides nutrition to the plant. If your lilacs are not growing strongly, it may be advisable to apply a tree & shrub fertilizer early in the growing season.
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