From the page: A PET bottle holds more value than it seems
Idea 4
Mini seedling greenhouse
Seedling growers have always used plastic tunnels to create a humid, warm microclimate, speeding up germination. A cut PET bottle does the same in miniature: the transparent plastic lets light in, retains heat, and keeps moisture around the seed — exactly what it needs to wake up.
What you need
- A clean, dry 2-liter PET bottle
- Craft knife or strong scissors
- Light substrate (sifted soil mixed with a bit of compost)
- Seeds
- Water in a spray bottle
How to make it
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1
Cut the bottle in half (or leave 3 fingers uncut on the opposite side, forming a "hinge" that makes it easy to open and close). The taller bottom becomes the greenhouse base.
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2
Make 3 or 4 small holes in the bottom of the base with the heated craft knife: excess water needs to drain, otherwise the roots rot.
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3
Fill the base with about 3 inches of moist substrate, spraying water until it feels like a well-wrung sponge — neither soaked nor dry.
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4
Plant the seeds at the depth indicated on the package (rule of thumb: twice the size of the seed) and spray again on top.
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5
Fit the top part of the bottle over it, with the cap closed — it holds the moisture inside. Open the cap a few minutes a day so air circulates and prevents mold.
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6
Place it in a bright spot, but without strong direct sun, which would cook the little seedlings inside the greenhouse.
Finishing touches
When the seedlings have two true leaves, start opening the cap for increasingly longer periods over about five days — this gradual "hardening off" prepares the seedling for full sun before transplanting. Write the planting date and seed name on the bottle with a permanent marker.
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