Reservoir bins make it easy to keep your garden watered, maintained, and gopher-free! They save water by limiting evaporative loss, and bring your plants closer to person-height so it's easy to prune and harvest. Each bin can fit a large plant (like a tomato) plus several smaller plants, giving you a great return on a small planting area.
Step 1: Reservoir Bins for Easy Gardening
- Large, watertight bin of some kind. I'm using a mixture of black 40 gallon aquaponics bins and blue 55 gallon barrels I found on Craigslist. You could also use steel stock tanks, large ceramic pots, rubbermaid containers, anything that will hold a lot of soil and keep water in.
- Silicone sealant, to plug any leaks
- Flexible french drain pipe, also called "aggie pipe." You want the non-perforated kind for this project.
- Weed cloth
- Zip ties
- Twine (optional)
- Good quality soil formulated for use in pots, or an equal quantity of Compost, Peat Moss or Coir, and Vermiculite or Perlite
- Mulch. I use straw, available very cheaply in large bales.
- Craft knife
- Drill (optional)
Step 2: Preparing the Bins
The first step is to get your bins ready, making sure they are watertight. Reservoir bins work by storing water in the bottom of the bed, and wicking that moisture up to the roots of your plants as they need it.
If you're using 55 gallon barrels, you'll want to cut them in half horizontally to maximize their usefulness. I cut mine by drilling a hole for the jigsaw to fit in, then just cut around the middle, following the center seam. These barrels have two threaded bung holes in the top end, so I coated the threads with silicone and screwed them closed tightly. (In the picture I'm cutting the bottom off a barrel for another project, but it's the same process!)
Now is also a good time to prepare the site for your bins. Level the ground as much as possible, so your bins will distribute water evenly into the soil above. You can also create a flat soil shelf to set your bins on, if you'd like the plants to be closer to standing height.
Step 3: Building the Bins
Bring your empty bin and position it in its final spot. These bins are very heavy once filled, so unless you build them on a rolling platform, they won't be easy to move later!
- Cut a length of irrigation pipe so it wraps once around the inside of the bin, and reaches up the inside wall to the brim of the container.
- Cut a square of weed cloth large enough to cover the mouth of the pipe, and secure it with a zip tie. Place this covered end down into your container.
- Affix the open end of the pipe to the rim of the container. I drilled two small holes and used some recycled plastic twine to tie mine in place. This opening will be where you water your plants and refill the reservoir.
- With the pipe in place, start shoveling in your sand. You should aim to cover the pipe by an inch or so.
- Drill an overflow hole just at the level of the sand. This will keep your soil from getting waterlogged.
Step 4: Adding Soil and Plants
Now you're ready to add soil. Good quality potting soil is just fine, or you can mix equal parts of compost, coir, and perlite to create a light, rich soil for your plants. It's important that the soil not be heavy or clumpy, as the wicking action won't work well if moisture can't move easily through the soil.
Fill the bin with soil to about 4 inches from the top of the bin. Add in your large plants, like tomatoes, then fill with smaller plants and more soil as needed. Leave at least an inch at the top of the bin for mulch.
Once everything is planted and the mulch is down, water the bin from the top to ensure all the soil is moistened. Keep an eye on the overflow hole on the side of the bin, and stop watering when you see water start to trickle out. I like to water from above while my plants get established, but the bigger plants will quickly put roots into the damp soil and start drinking from below. You can fill the reservoir directly by putting your hose into the pipe end, and filling until you see the overflow.
I typically water twice a week in the summer, since I often have new or smaller plants that need some additional attention. Otherwise, the tomatoes can happily go a week or more in a reservoir bin with no additional watering!