Create your own PC moisture sensor via PS2/Gamepad Controller
15.9 years ago electronics, water
Yet another component for “Project Everbearing” where I need the ability to monitor the moisture level of my soil. There are a couple options on how to do this; the classic method is to take two galvanized nails at a fixed distance apart in the soil. If you run electricity through one of the nails, some of the electricity will pass through the other nail depending on the amount of moisture, in much the same way as a variable resistor works. If the soil is completely dry it will have no conductivity (infinite resistance) since low voltage electricity does not pass through dry soil, as water is added the resistance is decreased and with completely drenched soil almost having complete conductivity.
Unfortunately, I did not have any galvanized nails and with our current snow storm I wasn’t going to venture out to the local Home Depot. I did fortunately have something even better, a handheld soil moisture sensor, which I bought when I started gardening before I learned I can see if I need to water by putting my finger in the soil.
With a little manhandling I got the cover off the back and realized that this tool works with the same principle as the galvanized nails with just two wires with provide variable resistance depending on the water content.
[And I thought my soldering was bad]
Now all that is needed was to solder these wires to a couple open points on my PS2 Controller which I am already using as a cheap temperature sensor The great thing about this implementation is the “resistor” has a broad range from no conductivity to nearly zero. Which is great since it gives a very accurate representation of the soil’s water saturation. For the calibration I was a little lazier this time and only took two points “Dry” and “Really Wet” With these measurements I then calculated the water saturation percentage. So now I can see my plants are at a 43% water saturation level, which I have no idea what exactly that means, but I do know I don’t need to water for a few more days.
One warning though since electrical conductivity can be affected by application of fertilizer (especially synthetic fertilizer which may contain sodium) and temperature so accuracy may be around 70-85% but for higher accuracy there are other expensive ($500) alternatives out there but I can live with this for my application.
Tags: cheap, outdoor plants, vegetables
Plants reveal your gardening shortcomings through Twitter
15.9 years ago electronics, water
Botanicalls DIY Plant Twitter Kit is an electronic device you insert into your houseplants and by giving them access to the Internet via Ethernet jack, they kindly praise you when water them and scold you when you are slacking via Twitter for all the world to see. At $99 per unit and require assembly (soldering) might be more cost effective to just let your plants die or at least get watering back into your winter routine. Though I imagine with a PS2 Controller, handful of galvanized nails, some wire, and a little coding someone could put together a cheaper solution. Guess who grew up watching every episode of MacGyver, this sounds like possibly one more project to add to my long list…
Tags: cheap, outdoor plants, vegetables
How to water your garden
16.4 years ago water
Many people may look at the topic of this post and think how basic a topic this is. The reality is proper watering is the most difficult part of growing a garden. The challenge ensures in the fact that roots need to stay moist, but not too moist since roots do not grow in the soil but in the space (air) between it so with too much water your can actually drown your plants. What makes this even more complicated is the visual signs of overwatering are the exact same as under watering with wilted leaves and yellowish color. Your immediate reaction is, “I am not watering enough” so you water more drowning the plants even more and eventually leading to their demise. Even if your plants look ok you still could be affecting your harvest. For example, if you overwater your tomatoes they will be green enjoying the perfect environment and never get around to creating some blossoms which will result delicious fruit. At the same time under watering your leafy plants can result in bitter tasting lettuce or even worse make them go right to seed and get very little or no harvest in plants like cilantro and spinach.
How do I know how much I need to water? Unfortunately the answer to this questions is “It depends” first you need to determine the structure of your soil (sandy, loam, or clay) If you do not know the structure of your soil you can to a simple glass jar soil test Sandy soils allow water to drain very quickly so you will need to water about three times as often as clay soil and about twice as much as loamy soil. If you live in a dry climate or just have a couple really hot weeks in your not so dry climate you will probably need to water at least every day to keep your plants healthy regardless of your soil structure.
The next factor is how deep do you want the water? It is important to make sure water actually gets to where the roots are, which has been the demise of my first years of tomato plants. Where I watered the surface but the soil was bone dry a several inches below the surface which I realized once I pulled out the dead plants. So first know your plants root system if you are growing deep root plants such as tomatoes, corn, cucumbers, peppers, beans, squash, eggplant, or melons you will need to water longer to ensure that the water makes it down to their deep root system but you can water less often since you will not lose as much to evaporation. If you are growing lettuce, spinach, carrots, radishes, peas, garlic, onions, cabbage, cilantro, or broccoli you need to water less but more frequent to ensure the soil stays most.
Now hopefully you have a better idea when and how much to water, here are some tips from Mel Bartholomew from “Square Foot Gardening” books/videos/PBS series. His first tip is “Don’t water from overhead” since first you waste water due to evaporation but you also get you leaves wet which can lead to disease and frying your plants. If you must water from above if you have a very large garden or if you are away from your garden and need to automate the process, he insists this is done first thing in the morning. If you are like me and enjoy sleeping at dawn you may want to look into his cup and bucket watering method where you fill up a couple of 5 gallon buckets and let them sit out in a sunny spot. You get the benefit of the sun warming the water to prevent shocking the plants with cold tap water especially on a streak of hot summer days. Another benefit is gives time for the tap water to purify itself a little before applying to plants. Once you have your bucket of water the concept is pretty simply just find a nice container (I normally raid my recycling bin) and scoop water out of the bucket and pour it directly under the leaves of the plant with little water waste and the delicate leaves remaining completely dry. This is also helps you measure exactly how much water you are giving to each plant which you can adjust as needed. You can also get some of the same benefits by using a trickler hose of a bubbler attachment if your back can not take the weight of packing around 5 gallon buckets full of water.
Now if after all of this explanation I haven’t scared you too much in fear of not watering too little or too much here are a couple more tips to make your watering more successful.
- Order on a consistent schedule: It is easy to forget the last time you water and watering a few days late or early can have significant effects on your harvest.
- Have a test hole: Normally there is somewhere in your garden where something is not currently growing after doing you normal watering dig into that hole and see how deep your watering is actually getting.
- Finger test: By sticking your finger into your soil if it comes back dry you probably need to water
- Get a water meter: If you want something a little more scientific you can always pick up a cheap water meter for less than $10 which can give you a measurement several inches underground
Tags: cheap, cilantro, garden seeds, garlic bulbs, led, outdoor plants, pepper plants, tomato plants
