Can this be used to test for all plants? I have a large vegtable and fruit garden and needs to find out what to add to soil for each plant.

Yes a moisture meter is a handy gadget to measure humidity in the soil of a vegetable and fruit garden. This device helps prevent overwatering or underwatering your plants. Usually it has a scale of 1 to 10, with 1 being most dry and 10 being most wet. Moisture meters are not expensive and can check plant moisture rather instantly. Thanks, Panacea Products