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Auto-Watering with Grow

2022-02-24 | By Pimoroni

License: See Original Project

Courtesy of Pimoroni

Guide by Pimoroni

Automatic, systematic and hydromatic, Grow is a smart modular monitoring ‎system designed to help you take the best possible care of your plants. It will ‎tell you how well they're hydrated, attract your attention when they need ‎water and, if you want to go a step further, even give them water!‎

Our first Grow tutorial shows you how to attach Grow HAT Mini and its ‎moisture sensors to your Raspberry Pi, how to install the software and how to ‎calibrate the values for your pots and soil. In this tutorial we're going to show ‎you how expand your system to let it water your plants automatically! We'll ‎assume you've got a Grow monitoring system (like the one below) already up ‎and going.‎

plants_1

Please excuse the droopy chilli, it perks up by the end of the tutorial.‎

What You’ll Need

As well as a Grow monitoring setup from the previous tutorial, you'll also ‎need:‎

  • Three suitable pumps
  • Silicone tubing (1m should be enough to connect all three pumps ‎unless you're planning a particularly expansive setup.)
  • A water reservoir (we've gone for a small plastic storage box with a lid, ‎but there's lots of containers you could use - read on for more ‎suggestions!)
  • A way to fasten the ends of your tubes securely over your plant pots ‎‎(we used thin gardening wire)
  • A drill, Dremel, craft knife or some other means of making holes in your ‎water reservoir

Caution - Please Read First!

‎A few quick safety notes before we begin, as we are playing with water and ‎electricity which (as we know from Pokemon) do not traditionally mix very ‎well. You'll want to position your auto-watering system as far away from ‎plugs and mains power as you can and it's a good idea to put the whole thing ‎on a tray or something similar, so if you get any water escaping it won't get ‎anywhere dangerous. Getting the settings right might take a bit of ‎adjustment, so don't leave your system unsupervised until you're sure that ‎the auto-watering is behaving as expected - maybe turn it off overnight for ‎the first few nights?

‎Another thing you'll want to avoid is inadvertently starting a siphon with your ‎pumps - this could result in your entire water reservoir emptying into your ‎pots quite quickly, which your plants won't appreciate. If you always make ‎sure that the plant ends of your tubes are higher than the water level in your ‎water reservoir, they should be safe!‎

Selecting a Water Reservoir

reservoir_2

We've selected this 1.5L Whambox as our water reservoir as we had it lying ‎around from back when we were allowed to go to shops, but we'd encourage ‎you to use whatever suitably sized plastic box you have to hand. Ice cream ‎boxes, the tall plastic boxes laundry pods and dishwasher tabs come in, ‎or Really Useful Boxes (Reight Useful Boxes if you're from Yorkshire) would ‎all be good candidates - you'll want something big enough for all your pots to ‎stand comfortably on top of, and at least 3 inches deep. In a pinch (or while ‎you're prototyping) mugs would also work as your water reservoir though you ‎might need more than one to make room for all your pumps.‎

Making Holes in Your Reservoir

After peeling off (or covering up) any unsightly labels, you're ready to make ‎some holes for your tubes. An 8mm drill bit (or a step drill bit) is probably the ‎neatest way of doing this, but you can also use a dremel to make the holes, ‎or a soldering iron or hot skewer to melt them (if you choose the last option, ‎make sure to do it in a well-ventilated area).‎

Assuming you've got three pots and three pumps, you'll need three holes - we ‎made ours about an inch down from the lid and spaced out them out, so ‎they'd line up with the pots once we sat them on top, and we drew on the ‎hole placements with marker pen before we started drilling in case we forgot ‎what we were doing halfway through.‎

holes_3 

You'll also need a hole for the wires that connect the pumps to Grow HAT ‎Mini to go through. We're planning on putting our Pi in front of our pots, so we ‎made another 8mm hole near the front of the lid.‎

lid_4

If you've got room, you could also make another larger hole in the lid so you ‎could fill up the reservoir without taking the lid off.‎

Connecting the Pumps

Locate your tube and chop it into three equal lengths. Depending on how ‎you're positioning things, the tubes might end up being a bit long, but you can ‎always adjust them later. Poke the three lengths of tube through the holes in ‎the back of your water reservoir, and then plug the ends of the tube into the ‎outlets on the pumps.‎

connect_5 

We then threaded the pump wires through the hole in the top and popped the ‎lid on. You could fill up the water reservoir here if you wanted to avoid having ‎to backtrack later on.‎

The pumps connect to Grow HAT Mini via two pin Picoblade compatible ‎connectors. These plug into the back row of ports which are slightly squarer ‎than the ones for the moisture sensor wires. You'll want to make sure the ‎pumps are plugged in to the HAT so that they match with the correct ‎moisture sensor for the pot they'll be watering (so the pot containing the ‎sensor attached to S1 should be watered by the pump connected to P1). It ‎could be helpful to draw coloured dots on the connectors and the sensors ‎themselves so you can keep track of which one is which and match them up ‎correctly.‎

dots_6

The connectors will only go in one way round, so if they don't fit, try rotating ‎them. If you need to remove them, make sure to pull on the plug rather than ‎the wires so you don't detach the wires from the connector.‎

wires_7

Once you've plugged them all in, you can poke the pump wires back down ‎into the water reservoir so they're out of the way.‎

Attaching the Tubes to the Pots

When figuring out how to attach the watering end of the tubes to your pots, ‎you'll want to consider two things!

‎Firstly, you should make sure the tube end is securely fastened in place over ‎the pot - if it comes adrift, water is likely to go places it shouldn't. Secondly, ‎you should aim to have the tube end positioned well away from the surface ‎of the soil to avoid soil being sucked back down the tube at the end of a ‎watering 'pulse' - if soil gets inside the pump it could jam or damage it.

‎We're making a loop out of gardening wire to hold the end of the tube in ‎place, you could also use craft wire or even electrical wire if it's the kind that ‎holds its shape. Something galvanised or plastic coated is better so that it ‎doesn't rust. Cut a length of wire about 10" long, find the middle and twist it ‎into a loop around the tube.‎

loop_8 

Twist the 'stem' a few more times, then wrap the ends around the pot and ‎twist to secure.‎

twist_9 

Alternatively, if you've got access to a 3D printer you could give these little ‎custom widgets a go!‎

widgets_10

Once you've anchored the tubes to the pots, you'll probably find that you'll ‎need to rearrange the pots and adjust the angle of the tube to find a position ‎that they sit nicely in - the tube is quite springy. We ended up adjusting the ‎tube on the left, so it pointed more towards the middle of the pot.‎

You can now plug the moisture sensors back into the top row of connectors ‎‎(remember to make sure they're plugged into the correct connectors). When ‎positioning the moisture sensors, you'll get more consistent readings from ‎the sensors (and more consistent watering) if the water's running on to the ‎soil rather than hitting the sensor itself. You can trim the length of the tubes ‎if necessary once you're happy with their position.‎

Now is a good time to fill up the water reservoir, if you haven't already.

‎Once everything's securely attached and suitably positioned, you should have ‎something like this:‎

secure_11

Enabling Auto-Watering

Once the Pi's all powered up, and the Grow service has started, you'll need to ‎turn on auto-watering (it's disabled by default). Before doing this, it's worth ‎quickly double checking that all your tube ends are positioned over your plant ‎pots, just in case.‎

postiion_12

You can find the setting to turn on auto-watering in the channel settings ‎menu - press the > button to cycle through the channels, and then the cog ‎button to change settings for that channel. Press the 'Next' button to cycle ‎through the settings until you get to 'Auto Water', and 'Change' to set it to ‎‎'Yes'. You'll need to enable watering for each channel individually. There's ‎also options in the channel menu to change the pump time, pump speed, ‎auto-watering level and auto-watering delay via the HAT- more about what ‎those do later on.‎

If you don't see any of the auto-watering options in the menus, you will ‎probably need to update your Grow software to the most recent version. This ‎will reset your settings to the defaults, if you've got wet and dry points, you're ‎happy with make sure to note them down first so you can re-enter them after ‎you've updated. You can grab the latest version of the software by entering ‎the install command again in the terminal - you'll want to stop the service first ‎if you have it running.

‎sudo service grow-monitor stop

curl -sSL https://get.pimoroni.com/grow | bash

Configuring Auto-Watering

We've provided some reasonable defaults for the auto-watering settings, but ‎you'll probably want to tailor them to your own setup. If you haven't already, ‎we'd strongly suggest revisiting the calibration section of the previous ‎tutorial and setting up custom wet and dry points - this will make getting the ‎auto-watering settings right much easier.‎

There are five water related values you can change via the menus in the ‎Grow monitor. Whilst adjusting these settings, it's worth bearing in mind ‎that Grow will work best if it gradually, gently dispenses water - you'll want ‎to aim for the smallest trickle being dispensed from the end of the tube, that ‎way Grow will be able to maintain the moisture level with the greatest ‎precision (and hopefully avoid unwanted flooding). We'd suggest starting with ‎low values for pump speed and pump time, and only turning them up if you ‎need to.‎

Auto Water: Yes/No - turns auto-watering on and off.

Auto-watering level - this is the saturation level at which Grow will provide ‎water to your plants. Setting it as 0.8, for example, will mean waterings will ‎be triggered when the soil is below 80% saturation.‎

Auto-watering delay - the time between waterings, in seconds. Setting it at ‎‎30 or 60 secs is a good idea as it means the water has time to permeate ‎through the soil and be measured accurately by the moisture sensor.‎

Pump speed - the power at which the pump runs. We'd suggest using 0.3 or ‎‎0.4 to start with, and only adjusting it up if the pulses of water are not making ‎it from the reservoir to the end of the tube. 1 is full power.‎

Pump time - how long the pump stays on for (in seconds) and thus how long ‎a watering 'pulse' will be. The default is 0.5, which seems like a reasonable ‎pulse length for most purposes.‎

There will likely be some adjustment required to find the right levels for your ‎setup! As we said at the beginning of the tutorial, we'd suggest not leaving ‎your setup unattended or overnight until you've monitored it for a while and ‎are happy it's working as intended.‎

As well as changing these values from Grow HAT Mini's menus, you can also ‎edit the settings file directly from your Pi's terminal (or over SSH, if your Pi is ‎set up headlessly) with

sudo nano /etc/default/grow

values_13 

It's Ctrl-X to exit Nano when you're done, and if you're editing the settings file ‎directly, you'll need to restart the service afterwards for it to use the updated ‎settings:‎

sudo service grow-monitor restart

Next Steps

Hopefully that will help you get started with the basics of an auto-watering ‎plant monitoring system - as always, tweet us @pimoroni and let us know ‎how you're getting on. We've tried to keep this tutorial straightforward and ‎only use basic supplies, but it would be very possible to build elaborate ‎setups with bigger pots, trays, or even 3D printed pots or mini greenhouses ‎‎(and maybe even introduce some plant lights or a water sensor to tell you ‎when the reservoir is empty). We'd love to see what you come up with!‎

Here's what our little Grow setup eventually morphed into - we told you the ‎chilli perked up :)‎

setup_14 

That's all folks!‎

制造商零件编号 PIM510
GROW KIT
Pimoroni Ltd
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