Normally, the pipes are blown empty with a compressor in autumn. It works like with the irrigation, only that circle by circle is emptied with air. Therefore, it makes sense to install an air pressure connection in the valve box(es). Another option is frost-free installation and self-draining housings. Option 1 is more economical and simpler.
Hello Birgit,
an irrigation system in your garden is more of a gimmick that can be a lot of fun for some people. If it's about an inexpensive and pragmatic solution: use lawn sprinklers and that's it. For new plants, the hose is used again and again, or just use a drip hose.
Sometimes simple is just as good.