The answer to 'best time for shrub' is that the best time to plant or transplant shrubs is typically in the fall, when the soil is still warm and the plants can establish their root systems before going dormant for the winter. This allows the shrubs to get a head start on growth in the spring.
Fall planting is ideal because it gives the shrub's roots time to acclimate to the new environment before the hot, dry summer months. This helps the shrub establish itself and become more drought-tolerant. Spring planting is also an option, but the shrub may need more frequent watering to help it get established before the summer heat arrives.