As the title suggests, I'm currently germinating a bunch of lemon balm seeds in an egg carton. I heard they grew better uncovered so I didn't cover them, however, they seem to dry out rather quickly, so I was wondering if I could make a simple DIY self-watering system for such tender plants. I searched for hours on Youtube but found nothing that was suitable for small containers and plants. I'd prefer: -It doesn't drown and overwhelm the seeds -It doesn't require a lot of materials. As shown below

If possible, I'd want: -A Video Tutorial perhaps? -A step by step tutorial in words? Thanks

  • This is funny, im working on a similar project to water my plants from a web page when i'm away. I'll post an answer involving arduino as soon as i'm finished ! Requires quite a few materials though.... Commented Sep 3, 2017 at 10:34
  • @RomainBruckert Nice of you to post here. My boyfriend was also planning to use Arduino for watering my plants so that we could leave home for a few days without any woriies, but somehow this plan is always postponed because of lack of time. I'm glad to know other people think about it.
    – Alina
    Commented Sep 3, 2017 at 16:48
  • 1
    Lack of time... True ! I'm also trying to struggle finishing that...😂. But every part is working at this date so i'll post all the parts references and arduino code very soon, stay tuned @alina ! Commented Sep 3, 2017 at 17:44

3 Answers 3


What I usually do for seeds, and since they don't mind being overwhelmed with water (different thing when the plant has grown), is the following.

I don't use plastic, the soil does not breath; I use small pots with holes at the bottom and leave them on a hollow plate. The soil sucks up the water from the plate and stays moist, yet not soaked.

Another thing to consider, especially if your plant is destined to be quite big, BIG pots are better; the more soil the longer it takes to dry. Simplest solution ever ; -).

One last option: put that in a box and cover the top with transparent plastic film and a few tiny holes at the side of the box. Humidity will stay, eventually drops of condensation fall back on the soil. (leave 10/15 cms of air volume if you cover them)

  • Thank you for the answer, it was really helpful. It only requires some water changing every once in a while but it's great. I use this as a germinator only, once the seeds sprout, I will transfer them to a larger pot. However, I still need some instructions since I don't know when to transfer them. Do I transfer them instantly when they sprout? Or let them grow for a while before transferring them? Commented Sep 9, 2017 at 4:55

One way this is done on a larger scale (it might provide food for thought, or perhaps you are a person who likes to tinker with automation on a smaller scale):

A "mist sensor" is basically a bit of mesh on a balancing arm (weight-adjustable, this is nice image since you can see the weight inside the shield)

Mist sensor

Image from www.sagehort.com.au which I'm not in any way associated with, just the most suitable image I could find quickly.

The mesh collects water droplets and becomes heavier, so it drops, and then changes the state of a switch.

This is used in conjunction with a mist irrigation system, which produces very small droplets. The sensor gives the system feedback about how much mist has been deposited, and then how fast it's evaporated. It's more typical in a "mist propagation system" to keep cuttings with leaves moist, but can also be used for very small seedlings as it's extremely "gentle" watering. One issue is to make sure that the watering system cuts off early enough that the plants do not spend the night with wet leaves, which can aggravate or cause fungus/rot problems.


I'm new to self watering pots, so I'm not an expert on the subject.

Try making a self watering plant container using tupperware from the dollar store, and some shoelaces (also cheap at the dollar store). I get 4 pots for $1, and 4 laces for $1, so this would make a fun/cheap experiment.

I just tried it about 10 days ago, and my basil is sprouting up in both pots. So far, so good.

To avoid root rot, make sure you use potting soil, since it's more airy. One of mine, I used backyard dirt, and I can tell it might be a little too wet near the bottom when the roots grow deeper.

  • You can germinate basil in wet hydroton Commented Feb 20, 2018 at 9:44

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