self-watering planters with coconut oil pails

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mishmish

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Another covid-19 quarantine project: a way to use up all of those empty coconut oil pails. I must have about 40 of them stacked up in the basement. I decided to take out my raised garden beds because the trees have grown so big the beds are too shady now to grow tomatoes. Also, watering is my least favorite thing to do, even in the raised bed. So I've been watching Youtube videos and am ready to start turning these buckets into planters that I can move to where the sun is.

You need two 50 lb buckets for each planter, a 1.25" diameter pvc pipe that's 2 1/2 ft long and has one end cut at a slant, a power drill with a 1/2" drill bit, a 1.5" hole cutter drill bit, and a 3" hole cutter drill bit, an x-acto knife, and a plastic Solo Cup or container of a similar size. You drill a 3" hole in the center of the bottom of one bucket, and a 1.5" hole as close to one side of the bottom of that bucket as you can get. Put that bucket into another one and hold them up to the light. See where the bottom of the inner bucket comes to, measure about 1 inch below that and drill a 1/2" drainage hole through the side of the bottom bucket at that point. That keeps the bottom bucket from getting too full of water and drowning the plant roots and causing root rot.

Insert the pvc pipe through the smaller hole in the inner bucket, slanted end down (that allows water to flow through without getting blocked). Take a plastic cup or yogurt container and drill some random holes in the bottom and carefully cut some verticle slits around the sides, without cutting all the way up through the rim. Push that cup down through the center hole so it fills the hole. It should leak water but not let dirt fall through.

Now you're ready for the soil - everybody seems to recommend a mixture of compost, peat moss, perlite or vermiculite, and some granular fertilizer. Plant your plant. Now pour water down the pvc pipe until some water starts coming out of the drainage hole. The soil in the Solo cup acts as a wick that pulls water up into the rest of the soil and your plant's roots will be able to use as much as they need. I've seen versions where you drop a thin lightweight stick or something into the tube so that it floats on the water in the tube - when the stick goes down, you know you need to add more water to the tube.

This is the theory anyway. ;-) I'm going to try to get one made tonight. Has anybody else made one of these? Did it work? There are other designs, some more complicated and some even simpler but I like this one because it uses two buckets and that will empty out my basement faster! They would make a nice gift for anyone who has limited gardening space.
 

mishmish

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I had to abandon the 3" hole cutter after a near-accident with the blade skittering off the plastic and nicking my jeans. It took longer but I used a regular drill bit (3/8"?) to drill lots of small holes In a 3" circle like perforations that I could cut out with a knife. The 1" (actually it was closer to 1.5") hole cutter was easier to use. I have one pot done and planted, two more ready to plant, and about 8 more all but ready (still have to cut the water tubes). Ordered some basil seeds and have some bush cucumbers and more tomato plants to put out. I have to make a trip to the gartden center to get more potting soil (or ingredients to make potting soil). It will be nice to get these done.
 

Marsi

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The near-accident was a close call - glad you are uninjured

Three things
Add an outlet tube to the drainage hole, the excess water will dribble down the side if there isn't an outlet tube (makes a mess, and the two bucket design is otherwise clean enough to use indoors), A short piece of irrigation tubing is about the right size

Go with the level float indicator, it saves time
Mark the float level stick to indicate when the water level is just below the outlet hole
Avoid overflow by looking for this high-tide float mark when filling the water reservoir

Never let your cup of soil (the wicking soil) dry out, it can lose it's ability to transport water upwards if it becomes dry and the soil might not re-wet easily
Make a second mark on your float level stick at the water level just above the bottom of your soil cup
Add water promptly if you see this low-tide mark

If you do dry out your soil, fill the bottom bucket by watering from the top (it's slow, but this has the best chance of re-wetting your dry soil - this works only sometimes, better to never let a wicking system dry out)
An alternative is to fix a strip of plain cotton fabric (or jean fabric ;)) to the top bucket, thread that strip through the cup and make the strip long enough to reach the bottom of the bottom bucket - this will help keep your cup soil moist so the system will start up again when you add enough water - the cotton will rot in about 3 years, so cycle in a new piece each time you re-do your planting

Was that four things? Sorry, I got a bit carried away
Yes, the system will work

Could we have photo's of your system in action? :thumbs:
 

mishmish

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When I plant the bucket, should I water the plant in from the top like I would if I were planting it in the ground? Besides filling the reservoir below, of course. Would coconut coir be a better wicking agent in the cup than potting mix (or maybe it doesn't matter)? I'll incorporate the cloth wick idea too - I've got lots of scrap cotton fabric around that I can use - old painter's cloths that have been washed many times.

I thought about the float stick yesterday. :) I'm going to see if I can rig something up with materials I can find here at home. A use for those wine corks!

I'm worried about how to keep the buckets upright when the plants start growing and become top heavy - we have high winds sometimes and it would be a shame for the plants to get broken just when they are starting to produce. Maybe I can lash the buckets together somehow so that they lend stability to each other. I'll take some pictures as I make more of them today.
 

mishmish

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Marsi, do you happen to know if there's any problem with mosquitoes using this system? Could they enter the bucket through the drainage hole or down the water tube to lay eggs in the reservoir bucket? We have a horrible mosquito problem here!
 

Marsi

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Lashing 3 or more buckets together is generally a good idea (you might need to prune the tomato plants if they get crowded)
Lashing the buckets to a fence or some rigid structure (like a stake in the ground) is best for really high wind areas
A layer of crushed rock/gravel/pebbles in the water bucket adds weight - even when the entire water containing area of your wicking system is filled with gravel the system will still work (the water volume will roughly halve in my test with medium grade, 5-20mm red basalt gravel)

Coconut coir is the eco-friendly version of peat moss - it holds water and releases it slowly into the soil
By itself Coconut fiber dries out faster than peat moss and gets water repellent when dry
It is a good idea to blend some coconut coir into your wicking cup soil or blend the coir into your whole mix (I like the simplicity of having just one soil blend for the whole structure, including the wicking soil, and the coconut coir is a cheap ingredient)

Mosquitoes can access the water via the inlet pipe
A square of your painters fabric held in place with a rubber band will solve that problem temporarily (you will need to take it off to check the float)
A pvc end cap with a snug holed drilled in it for the float stick to move is a good permanent solution (the end cap is cheap and easy to source, the hole can be sandpapered to make the float operation smooth and if you need to, a small roll of old curtain netting can be glued inside the cap to brush up against your level so no insects can get past, and the end cap is easy to lift up to water)

Normally you would water the plant via the reservoir only - tomatoes and cucumbers do well with this system as the lack of overhead watering reduces fungal issues (still prune the tomatoes for good airflow if they get crowded)
The surface soil will likely be dry - test for moisture from about an inch under the surface
If your plants are not getting enough moisture, modify your system to use multiple wicking cups

Nice setup!
The extra holes you drilled into the base are good for drainage when it rains :thumbs:
(with the two-bucket system, dripping sounds into the water well after rain means your drainage and overflow systems are working)

I like your wine cork float idea 😁
 

mishmish

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To resolve the mosquito problem, I got some stainless steel pot scrubbers, stuck each one into an old knee-high stocking (weird the things that I still have around the house) and stuffed one down each pvc pipe. The stocking makes it easy to pull out and they are malleable so they take the shape of the pipe.
 

penelopejane

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If you stick electrical tape or duct tape where you want to drill a hole using a hole saw that will help get it started so it doesn’t kick up at you. Once started remove the tape.
Or tilt the saw a tiny bit so you are pushing a little more on one side. This will Make it easier to start the hole and avoid the kick.
 

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