Feeding Tomatoes via an irrigation system

Question

OK, so I have set up my greenhouse with growbags and an irrigation system, and am having good results with growing several varieties of tomatoes and chilies. I'd prefer to automate the feeding of my plants though, so am considering adding a Venturi injector onto the main feed lines so that I can add feed directly via the drippers.

I'd like to know:

1. Is mixing Tomorite with every watering a reasonable idea or beyond stupid?
2. If it is reasonable, how should I adjust the amount of feed? The bottle says 4.5 liters + 20ml of feed per bag, twice a week, but for continuous feeding, I'm assuming I'd need to set the feed amount to some ratio that's much more dilute.
3. Has anyone done this and had success or problems?

ADDENDUM

I received a reply from the manufacturer:

Thank you for your email regarding Levington Tomorite.

As yet we have not tested this product with automatic irrigation systems so cannot offer any advice. Continuous feeding can lead to a build up of "salts" in the compost which can harm plants if not flushed through with clean water on a regular basis.

So to be on the safe side, rather than add a weak solution to the drip feeder, I'm going to opt to leave them unfed during my time away.

Answer 1

Sorry, I disagree with Stormy here - and this is 1 area I have experience - you absolutely can grow tomatos well on a schedule and with automated watering. (I've done it sort of - I have done it proper with Eggplants - commercially - and had a couple of tomatos, cucumbers and Zucchini just plugged into the identical system - while it is ideal for Eggplants, they all grew fine).

I can't speak on the figures for tomorite (but I would guess they would be similar). The way this is done in a commercial hothouse is -

1. Water and liquid fertiliser are mixed into a large holding vat. (Actually the fertilisers comes in 3 parts - an A and B formulation + a separate PH regulator)

2. A pump system combined with a CF meter and PH meter is used to control the percentage of nutrients in the water. I believe that simpler systems do indeed do away with a pump and meters and simply use a Venturi, although you will want to check the dosing periodically.

3. A solar counter is used to monitor the amount of light, and waters the plants periodically by pushing the water/fert mix through pipes for a very controlled amount of time (ie whenever the solar counter has counted x amount of light on the plant).

I'm a couple of years away from doing this on a small scale, but I am absolutely certain you can do this whole thing with an arduino, sensors and some solenoid valves.

Another aspect is that growing is normally done in an inert medium like blown rock and/or cocopeat, with free drainage below the bags. I suspect this helps reduce buildup of excessive fertiliser in the soil equivalent (and reduces some disease risks - but also as a technique for intensive farm - a cucumber plant only lasts 3 months commercially !)

Another exciting system to look at - which takes automation even further (it does weeding, planting of multiple crops as well is Farmbot

I'm happy to answer follow on questions if you have them - this stuff is not really secret (there are tricks and optimisations, and over a large enough number of plants its still very labour intensive [or requires very expensive gear, but for a small garden you can largely automate it as you don't have the same pressures to produce high yields)

Answer 2

I feel it is fine to have an automated system IF you know what you are doing and check virtually everyday what is happening with the plants.

Otherwise, anything automated is going to get you in trouble. Plants do not do well with schedules and charts. If one can't grow successfully totally manual, automated will be a big bummer. All plants even the same variety will have different needs. Unless you are able to group all the plants with the exact same needs and MONITOR closely forget automation! Check out Shane Smith's Green House growing...he is spectacular in detail. Another priceless, new book is Jorge Cervantes 'The Cannabis Encyclopedia'...just because it is all about ONE plant (a weed at that) you will learn details and a way to understand how much us humans need to be aware to understand just by SEEING a plant what it needs or what it is getting too much of! And this is where automation becomes more necessary...with Cannabis.

There is no FAST way to garden other than getting the basics down and the use of automated systems, heck, I am NOT at all interested with automation for my very large greenhouse or gardens. Not worth the expense or trouble. Perhaps if doing huge commercial stuff but...otherwise, a waste of money and increase of distance between you and your plants.