First work out how many liters you need per square metre each day – a typical garden wants about 5 mm, so for 100 m² that’s 500 litres. If you plan to run the system for two hours, you’ll need 250 litres per hour, which works out to about 4.2 litres per minute. Add a 10–15 % safety margin for head loss and evaporation, so round to 4.5 l/min. Pick a pump that can supply that rate at roughly 2 bar, use a pressure‑regulating valve, and install a simple flow meter to verify the actual output. Once you’ve set the timer, tweak the duration until the soil feels consistently moist but not water‑logged – you’ll never need a second round if you get the maths right the first time.