[QUOTE=zipcode;763321]Do overwatering not at every watering then, and dose the fertilizer according with the runoff EC when you do overwater. It's really the root zone EC that matters mostly, and runoff EC will be a good aproximation. More frequent flushing will give a more stable nutrient solution (especially in terms of nutrient balance), there's a reason they grow in rockwool in top greenhouses. Also, as long as aeration is high (coarse peat is especially important, not sure what promix has), you can have high water retention, the roots don't rot from water but from lack of oxygen.[/QUOTE]

I'll give it a try, I've never actually watered to waste and captured the runoff to measure the EC before. I use ProMix HP, and don't add any additional components. I find water retention is still extremely high, at least in the PNW.

[QUOTE=dshreter;763327]I'll give it a try, I've never actually watered to waste and captured the runoff to measure the EC before. I use ProMix HP, and don't add any additional components. I find water retention is still extremely high, at least in the PNW.[/QUOTE]

I would try a smaller container or add more perlite to my mix, then they will dry out faster so you can feed more often. Like Zipcode said, some grow in Rockwool, Coir, clay balls, it goes on and on. Trial a few systems, methods, ferts, we learn best by stumbling forward over time. Good luck this year.

Mark, how did you decide on grow bags and fertigation as your method? I see a lot of the very large scale indoor commercial operations are taking hydroponics approaches, so was curious where that is practical, and when watering is best.

[QUOTE=dshreter;764535]Mark, how did you decide on grow bags and fertigation as your method? I see a lot of the very large scale indoor commercial operations are taking hydroponics approaches, so was curious where that is practical, and when watering is best.[/QUOTE]

Grow bags are cheap, we do mostly use hard plastic pots. Tried Smart Pots, and others too.
I use Pro Mix because I get a deal on it since we go through so much. We grow everything in it for the business which tomatoes are a small part of.

Our state Agronomist set me on my current path several years ago.

I can't hand water a bunch of plants, when March hits our death march goes until about this time of year, then we can take a breath. We walk 20-35k steps a day for over 100 days straight. lol

I have friends up here that grow too, we all have our twists, Bill grows in Rockwool, Arthur adds perlite to his HP, the next guy hydroponics, etc, etc.

Much of this stuff is trial and error/ stumbling forward, we won't reinvent anything, most likely, but a spin on some stuff is fun.
super easy, the least of my growing issues in a season.