The solution: self watering planters! Despite sounding kind of high-tech and robotlike, self watering pots or planters can be made very simply, with a reservoir of water that is slowly fed to the plants via an absorbent material, like strips of terrycloth towel, so they can go longer between waterings. They are also designed so the soil never stays overly wet, which can also cut production.
Here’s a step-by-step guide on how to make your own self watering planter with some basic supplies you probably already have.
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What You'll Need
There are lots of self watering planters, self watering containers, and self watering pots on the market, but if money is tight you can make you own serviceable self watering planter for a few bucks or less.
+ ¾" – 1" spade drill bit
+ ¼" wood drill bit
+ Scissors (if your cloth needs to be cut)
+ Organic potting mix, enough to fill one bucket.
+ 1 square foot of old terrycloth towel or 2 square feet of old, absorbent cotton T-shirt or sheeting
+ 2 food-grade (look for numbers 1, 2, 4, or 5 in the recycling symbol on the bottom) plastic buckets (4- to 6-gallon size is good). They don’t have to be the same but they need to nest snuggly into each other, leaving a 2- to 3-inch space between their bottoms. Some restaurants are willing to give these away.
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Decide which bucket will be the bottom/outer one. Slip the other bucket inside it and then make a mark on the outer bucket where the bottom of the inner bucket is. Lay the buckets on their side and drill a 1" hole (the exact size is not critical) in the side of the outer bucket just below the mark you just made. This is the overflow hole.
Remove the inner bucket and set it upside down. Drill a 1" hole (the exact size is not critical) in the center of the bottom of the inner bucket. This will be the wick hole. Drill about a dozen ¼" holes (the exact size is not critical) scattered over the rest of the bottom of the inner bucket. These will allow extra water to drip out of the soil and into the reservoir below.
Related: The Best Self Watering Pots And Containers For Your Plants
Tear or cut the cloth into strips about a foot long and 1"-2" wide. Gather one end of each together and stuff them through the large hole in the center of the inner bucket, leaving about 5" hanging down and the rest inside the bucket. If the fit is so tight you have to pull hard to get the strips through, leave out a strip or two; if they are packed to tight it may make the wick less effective.
Slip the inner bucket into the outer bucket. Spread the wicks out in all directions. Fill with potting mix.
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Put the planter in its final location. If the surface under it may stain, you may want to place it in a large saucer to catch the overflow. Plant seeds or plants and water well, adding water slowly, until the water starts to dribble out the overflow hole on the side of the planter.
Add water as needed to keep the potting mix moist within an inch of the surface (just poke your finger in), adding enough so the water starts to dribble out the overflow hole on the side of the planter. Try not to let the soil dry out any deeper than the very top surface, as it can be hard to get it moist again.
How often you'll have to refill the reservoir will vary depending on the weather and the specific plant you're growing—as often as every other day in very hot, dry weather for a big, leafy plant (a big improvement over twice a day for the same plant without the reservoir) to once a week or less in cool, wet weather.
You'll also want to water with a diluted organic liquid fertilizer every few weeks, or according to the package instructions.
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Alternatives to plastic
Sigh. We live in a world surrounded by plastics. While food-grade plastic containers are inexpensive (and definitely safer than non-food-grade plastics), most probably contain compounds that may not be completely safe for humans or the environment in the long run, which may slowly leach out into the soil and end up in your plants.
After reviewing the available scientific studies on human health risks, I’m okay with growing some of my food in food-grade plastic buckets. However, I'd advise reclycling and replacing them when they become brittle, which usually ocurrs after 4 or 5 years in the sun.
If you are looking for alternatives for making a self watering planter and have some money to spend, here are a few options that fit the bill and might be a little safer in the long run:
Lots of swanky commercial planters are made with galvanized metal these days. You can buy galvanized steel buckets and trashcans at hardware and farm stores (my local one has a 6-gallon ashcan for about $20 that would work). I’d use one bucket and buy a disposable aluminum baking pan to make the bottom of the soil mix compartment, supported by some short bits of untreated lumber. Drill a hole with a metal bit about 3” from the bottom of the bucket.
Two downsides to galvanized metal: the rust-resistant coating contains zinc, which isn’t good for you in large amounts. Acid soil will increase how much zinc leaches into your soil and becomes available to the plants, so this probably isn’t a good choice for growing something you will use an acid soil mix for, such as a blueberry bush. And galvanized buckets will eventually rust, especially when keep wet, so the bottom seam is likely to start leaking in a few years, turning your self watering planter into a standard planter.
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Stainless Steel Or Aluminum Pots
If you can find large, affordable pasta pots they make dandy planters (check yard sales or the “scratch and dent” shelf at the local restaurant supply store) and won’t rust out the way a galvanized bucket will. Stainless steel is probably about the least-reactive material you are likely to find.
Fish Safe Pond Liner
You can buy sheets of thin, flexible “pond liner” designed for making fish ponds, which can be used to line containers to make them watertight (and prevent anything in the container from leaching into the planting mix). Look for a synthetic EPDM rubber one, as the material contains no plasticizers and is labeled as safe for fish, wildlife, plants, and drinking water.
You can build a sturdy wooden planter and line the entire thing with a single sheet of EPDM rubber, then cut a drain hole 3” from the bottom after the liner is settled. Once the liner is installed, create a sturdy perforated floor above the drainhole to hold up the planting mix and install wicks.