Thanks for the vote of trust, crabbyback. (but never miss an opportunity to double-check facts if possible. :thumbsup: )

A cheap (temporary) solution is to go get one of the aquarium ph test kits. There are two types available. One for saltwater (what I used to use for my 8.0 wellwater) and the freshwater kit. (lower range than the saltwater kit, but is good for lower ph water) Eventually you'll want a reliable ph pen (not a Hannah...unreliable) so you can monitor for changes in the runoff ph, too. (can't check runoff with those test kits)

Can also take a cup of tapwater to the aquarium store, and they'll test it for ya, which will help determine which test kit you should buy.

How long have they been in the same soil? How many internodes do they have? Which nutrients are you going to use when the time comes?