Plastic Bottle Self-Watering Planter for Herbs (2-Liter DIY)
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A plastic bottle self watering planter turns a 2-liter soda bottle into a windowsill herb pot in 10 minutes. Learn the build, the wick, and the 6 best herbs.
Quick answer
Cut a 2-liter bottle in half, flip the top half upside down into the bottom, and thread a cotton wick through the cap. Fill the bottom with water and the top with potting mix. The wick pulls water up as the herb needs it. One bottle planter holds 1 liter of water and feeds one basil, parsley, or chives plant for about 5 to 10 days on a windowsill. Wrap the bottom in paper or foil so light does not grow algae in the water.
What you need
A clean 2-liter plastic bottle with cap, a 10-inch strip of cotton cloth or cotton string, a utility knife or scissors, a nail or small drill bit, and 2 to 3 cups of damp potting mix. Wrap the lower half in kraft paper or foil to block light.
Use cotton for the wick. Nylon and polyester string move water poorly and often stop wicking after a day.
How the planter works
The top half of the bottle becomes a funnel-shaped planter that sits inside the bottom half. A cotton wick runs from the soil, through a hole in the cap, and down into the water. Capillary action pulls water up the wick into the soil.
Keep the wick snug but not packed. A strand about as thick as a pencil moves enough water for one herb.
Which herbs to grow
Basil, parsley, chives, cilantro, mint, and lettuce all like steady moisture. Mint is the easiest. Basil needs the most sun. Skip rosemary, thyme, and sage. They prefer dry roots.
A south or west window with 4 to 6 hours of direct sun works for most. Add a small grow light if your window is dim.
This is not your problem if
- You want to grow rosemary, thyme, or other dry-climate herbs.
- You have no window with at least 3 hours of direct light and no grow light.
- You already own a ceramic self-watering pot and like how it works.
- You need a planter that holds more than one herb. A bucket planter fits better.
Step-by-step: build the bottle planter
- Rinse a 2-liter bottle and remove the label.
- Cut the bottle in two about 1/3 of the way from the top, leaving a funnel top and a straight-sided base.
- Poke a 1/4-inch hole in the cap. Thread a 10-inch cotton strip through it with 4 inches inside the top.
- Fill the base with water until it is about 1 inch below where the cap will sit.
- Flip the top half upside down into the base, with the wick dangling in the water.
- Fill the top with damp potting mix, add a seedling, and place on a sunny windowsill.
Light tip: algae loves clear plastic. Wrap the lower half in paper, foil, or paint it with a coat of spray paint.
Herbs for the bottle planter
Light needs are for indoor windowsills in most U.S. climates.
| Herb | Plants per bottle | Sun (hours) | Days to first harvest |
|---|---|---|---|
| Basil | 1 | 6+ | 25-35 |
| Parsley | 1 | 4 | 60-75 |
| Chives | 3-4 | 4 | 30-45 |
| Cilantro | 2-3 | 4 | 30-45 |
| Mint | 1 | 3 | 30-45 |
Keep it healthy
Refill the reservoir when you see the level drop to about 1/4. Rinse the base once a month. Trim herbs often to keep them bushy, and pinch off basil flower buds.
Bottles last one season outdoors in strong sun. Replace if the plastic turns brittle or cloudy.
Myths that waste time
Myth: any string works as a wick. Cotton wicks. Nylon does not.
Myth: clear bottles are fine because herbs love light. Light in the water grows algae. Block it.
Myth: a bottle planter fits any herb. Rosemary and thyme rot with constant moisture.
Myth: you need to fill the water to the top. Leave a 1-inch air gap so the roots do not sit in water.
Do this today / this week
- Save two clean 2-liter bottles this week.
- Cut and assemble one bottle planter.
- Fill with damp potting mix and plant a basil or mint seedling.
- Wrap the base to block light and set it on a sunny sill.
- Check the water level every 3 days.
Frequently asked questions
How do you make a plastic bottle self-watering planter?
Cut a 2-liter bottle, flip the top into the base, thread a cotton wick through the cap, and fill the base with water.
What herbs grow best in a bottle planter?
Basil, parsley, chives, cilantro, and mint all do well.
How long does one bottle of water last?
About 5 to 10 days for one herb on a windowsill, depending on light and temperature.
Is it safe to grow herbs in plastic bottles?
Use bottles marked recycling code 1 (PET) that have not been in strong sun for long. Replace them once a season.
Key takeaways
- A 2-liter bottle, a cotton wick, and damp potting mix make a working herb planter.
- Use cotton for the wick, not nylon or polyester.
- Block light on the base to stop algae.
- Grow basil, mint, parsley, chives, or cilantro; skip rosemary and thyme.
