There will still be some steps needed to winterize your pond even if you don't have any fish in order to protect your equipment and keep your plants healthy. If you don't have fish in your pond, then you don't have to worry about keeping the water from freezing over. If your pond has a waterfall, stream, or fountain and your climate is cold enough for ice to form on ponds and lakes, however, you'll need to either keep those features running 24/7 throughout the season, or shut them down before the weather gets too cold. Honestly, it's safer to shut them down, since even a relatively brief power outage could allow ice to form in your pump and lines and damage or destroy the setup. Pumps should be stored in a bucket of clean water in a garage or a space where the temps do not dip below freezing. Pipes, hoses, and other equipment should be dried completely and stored in a similar space.
If you've got live plants, your hardy speciments should survive just fine outdoors. Trim them back severely at the first sign of frost damage and then submerge them completely in the deepest part of the pond. Tender aquatic plants can be brought inside and kept in an aquarium if you like, or you can discard them in the compost heap and start fresh in the spring. Some marginal pond plants can even be kept inside as houseplants during the winter. Larger plants that won't tolerate freezes can even be kept in small kiddie pools or similar temporary tanks in an area where the temperature will always be at least 40 degrees Farenheit. Don't forget that they still need sunlight!
