When choosing a location to plant a lilac bush near your house, it's important to consider its mature size to ensure it has enough space to grow without causing any damage. Typically, a lilac bush should be planted at least 5 to 15 feet away from your house. This distance allows the lilac bush to have ample space to spread its roots and branches without interfering with the foundation of your house. Furthermore, it also helps to prevent any potential damage to your property from the plant's root system or branches. Remember, proper planting distance not only ensures the health of your lilac bush but also the safety of your house.