From the page: The plastic bag deserves a second life
Idea 10
Bottle and bag greenhouse
The bottle mini greenhouse is an old technique of nursery growers and urban gardeners: a transparent cover creates a warm, humid microclimate, speeding up germination. The moisture stays trapped because water vapor condenses on the plastic and returns to the soil, like a miniature rain.
What you need
- Clean 2-liter PET bottle
- Clean plastic bags (several work)
- Scissors or craft knife
- Soil or substrate
- Seeds (lettuce, arugula, basil or cilantro)
- A bit of stone or gravel for drainage
- Rubber band or string
How to make it
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1
Cut the bottle in half or remove just the base, leaving a firm edge; the bottle's rigid plastic holds the structure while the soft plastic seals in the heat.
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2
Make 3 or 4 small holes in the bottom for water to drain — without drainage, the roots rot from lack of air.
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3
Add a thin layer of stone, then soil up to two fingers from the rim, and plant the seeds at the depth indicated on the package (almost surface-level for lettuce and arugula).
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4
Moisten the soil with a sprayer or light watering, without soaking; seeds need constant moisture, not puddles.
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5
Fit the top of the bottle as a lid, or stretch a plastic bag over the opening and secure it with a rubber band; the transparent plastic lets light in and keeps heat and humidity inside.
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6
Place it in a bright spot, but without strong direct midday sun — inside the greenhouse heat accumulates and can cook the seedlings.
Finishing touches
Open or lift the cover about 10 minutes a day to exchange the air and prevent fungus; when the seedlings touch the plastic, it's time to transplant. White or translucent bags work better than dark ones, which block the light.
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