need to find a hand held water meter

I need to find a good hand held water tester to stick in 4 inch pots to see if they are dry or not. Any ideas where I can buy a couple? thanks BEV

Take one of the pots, wet it thoughly, lift to feel the weight. Now let it set a couple of days, lift again. See the difference in weight. That is the best way.
You could probably kill everything by using a meter. Another way is to look at the top of the pot, when the potting mix looks dry & gray, it probably needs water. Overwatering is the biggest probelm in a greenhouse. If things are a little on the dry side they grow better & don't get leggy.
After a time your experience will make watering as easy as walking! LOL!
Have a great day!
Bernie