At the Festival of Ideas StreetFest, we demonstrated how to upcycle old plastic bottles into sub-irrigating planters for your home or office — it’s easy, inexpensive and eco-friendly! Made from 1L, 2L or 3L bottles, these planters are a great way to keep your plants happy without accidental over-watering. So many people asked for the instructions at the demo, we decided to post them here, on our blog!
Def: Sub-Irrigated Planter (SIP) is a generic name for a special type of planter used in container gardening. A SIP is any method of watering plants where the water is introduced from the bottom, allowing the water to soak upwards to the plant through capillary action (wicking)
What we love about self-watering planters, besides being easy to make, is that we don’t have to worry about over-watering our plants or under-watering them.
- Used Plastic Bottle (empty)(1L, 2L, or 3L)
- metal skewer
- potting soil
- permanent marker
- felt (optional)
- Remove the label from your bottle.
- Poke a series of holes in the neck and top of the bottle by heating a metal skewer over a gas burner. You can also use a wood burning pen or an electric soldering iron.
- Draw a straight line with a permanent marker around your bottle. A 14oz. can is a guide for how high up the bottle your line should be and helps keep your line straight. This is not an exact marker but a guide. The objective is to get the top of the neck to touch the inside of the bottom.
- Cut off the top of the bottle where the cap is located to keep the roots from clogging the bottle neck.
- Cut 1” of plastic from the bottom of the bottle to make up for the inch of bottle you just cut off. Make sure you cut straight!
- Get your soil and plant the top part of the bottle with seeds or your plant. The little holes are for the roots to poke out of so that they can soak up the water you will be putting in the base of the bottle. Don’t worry about the plant roots- they definitely know how to find water!
- Put the top of your bottle inside the bottom of the bottle and add water to the bottom part
- You’re done. Enjoy your beautiful new sub-irrigation planter.
- To water simply lift the top planter section from the bottom and add a measured amount of water, never add so much that it rises to the soil surface. The top ½” to ¾” should be dry. Remember… You are the self in self-watering
- For larger plastic containers like 5G water bottles, you can experiment by adding wicking material like polyester batting material (felt). Just pour some potting mix into the planter on top of the wick. Use a finger to push the soil down firmly until the wick protrudes at the neck opening. This will hold the soil in the planter and guarantees contact with the water
Many thanks to Groundworks INC for their help with this demonstration!