I have about a dozen plants (tomatoes, cucumbers, peppers) I'm wanting to fertilize automatically.

My wife has a couple of orchids, and I noticed she gets liquid fertilizer in a tube which she just upends into the plants once a month.

Does anyone know if I can make something similar for my plants using syringes ans what size syringes are appropriate? (I'm envisaging 50/100 mm syringes)

2 Answers 2


Actually there are some automated fertilizer injector systems available on the market already, albeit at a fairly high cost. Yes, you can certainly use a syringe for injecting liquid fertilizers into the plants, but you have LOTS of obstacles to overcome:

1) You have to devise a way to push the syringe at a very specific (low) rate (i.e. gears are necessary plus other parts in combination with a stepper motor)

2) You have to make the formulations yourself while ensuring that all the ingredients (usually various salts) get completely dissolved in the water and don't precipitate out later (especially iron compounds which are quite prone to this)

3) Special measures need to be taken to prevent mold/bacterial/algae growth in the syring because the nutrients (plus the water) will almost certainly attract them for sure

Thus once you know how to take care about all the aforementioned issues (and then some) you're all set.

  • I was hoping I would not need to do anything fancy (or use a working effect or similar). Thank you for your other points. I'll reconsider a venturie type mechanism for injecting nutrients. IM wondering how the orchid feeding system works.
    – davidgo
    Commented Nov 26, 2018 at 1:13
  • Well, those orchid drip feeder things I've seen are single-use only (that's why you don't need to worry about fungal/algae/bacterial growth with them) and orchids are epiphytes i.e. they don't grow in proper soil (in fact they don't grow in soil at all), so their demands are completely different from that of conventional vegetables. Moreover vegetables usually need plenty of water so instead of dripping fertilizers directly into the soil the usual way is to inject them into the irrigation water instead.
    – CoolKoon
    Commented Nov 26, 2018 at 1:25
  • Yes, you won't have to do anything fancy, but the things above still need to be accounted for (maybe you could get around the first problem, but there'd still be the problem of delivering the fertigating water to the plants).
    – CoolKoon
    Commented Nov 26, 2018 at 1:30

Look at a medical supply supply site/store ; various sizes are available .I have used plastic 60 cc/2 oz syringes for years to fertilize and water plants. I happen to have them for a medical situation but I know they can be inexpensive. No problems using them . I have a very large stag horn fern with a 16 " diameter "root ball" , the only way I can get water in to it is with the syringes. And several orchids in pots - very fast drainage, the best way to get water and fertilizer to the whole root area is with syringes.

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