Is it even worth planning that garden irrigation system if your spigot can’t produce the pressure you need? Do you need to break it into zones? There are two ways to find out — build it and discover it won’t work, or actually test it and build the system, taking the water pressure into account.
Rain Bird’s water pressure gauge hooks up to your spigot with a 3/4″ female hose thread adapter; judging from the numbers on the gauge it will read from 0 to 200PSI. If your water supply is reading 200PSI you might have an ongoing indoor watering project on your hands to take care of first.
Evidently the Rain Bird’s water pressure gauge is on closeout at Amazon right now where it’ll cost you about $8. So pick one up now for next spring.