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?


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.

  • 1
    If you can find a way to dilute it enough to do a continuous feed at the rate given on the package, it sounds fine (although residue may build up inside your irrigation system over time),
    – J. Musser
    Aug 8, 2016 at 21:22
  • @J.Musser thanks - I've also asked the manufacturer to see what sort of concentration I need / whether they recommend this approach at all. I know that salt can build up over time, but I'm hoping that as it's going to be dismantled and cleaned yearly, I'll be able to flush this and prevent problems.
    – Codebeef
    Aug 8, 2016 at 22:12
  • See my fuller answer below, but with respect of adding fert, rather to dilute then too strong.
    – davidgo
    Aug 10, 2016 at 6:11

2 Answers 2


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)

  • Ah - so this would be a hydroponic setup? Farmbot looks interesting, though maybe for a project when they are released and I can implement with a new raised bed :)
    – Codebeef
    Aug 10, 2016 at 9:59
  • Is there anything you'd consider recommended reading?
    – Codebeef
    Aug 10, 2016 at 10:00
  • @codebeef Technically its not a hydroponic setup as you are growing in cocopeat. Some laymen ro call it hydroponic though. Im pretty sure you can do the same thing in soil, but you will gave less controll of root disease (drainage/pathogens) and buildup of chems in soil at an even rate.
    – davidgo
    Aug 10, 2016 at 20:48
  • @codebeef sorry, dont have reading material recommendations. I bought the business and training. Maybe drive into countryside, find hothouses, explain your interest and ask if owner will show you arround
    – davidgo
    Aug 10, 2016 at 20:49
  • 1
    On many plants more flavor molecules are built when plants are in stress (cold or dry). So I would prefer quality over quantity (so less automatic). Manual checking and adapting is also more enjoying. Aug 11, 2016 at 10:00

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.

  • Yep, I do check every day, though as I'm going to be away for a period, I need some way of watering in my absence (hence the drip system). Adding feed to this is a natural extension. Not after a FAST way to garden, just something predictable that I can tune to the needs of my plants.
    – Codebeef
    Aug 8, 2016 at 22:09
  • 3
    This doesn't really answer the question. Automation is used across the world in commercial greenhouses with success.
    – kevinskio
    Aug 9, 2016 at 18:06
  • I do believe I addressed the commercial application of automation. But to have home owners relying on automation, especially fertilization is not something I will be promoting. Especially for most gardeners who use this site. Doubt there are many commercial OP's on here. Automation is fine and necessary once one already thoroughly understands plants. Going on vacation and watering is fine but unless they are going for a very extended time I disagree with the addition of fertilizer. Gees, check out my very last sentence. Best book on this stuff, 'The Cannabis Encyclopedia'...!!! Grins.
    – stormy
    Aug 10, 2016 at 21:15

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