"A stitch in time saves nine." There is no use planting 1,000 trees, only to see many of them die in the first couple of years. Good maintenance will ensure your project develops well, and your investments of time, money and energy bear fruit. Another slightly different aspect of maintenance is ongoing monitoring. This may be monitoring your monthly energy use, or the number of large fish in your pond. Either way, identifying what aspects of your project need to be regularly monitored will help you to make sure the systems you have installed are working the way you want them to.