Many people start seeds early indoors to give their plants a head start, especially in places with a short growing season. I don’t know about you, but I don’t like having lots of little containers of dirt and water hanging around in the house – I prefer to start my seeds outside in the garden. However, some plants need those few extra weeks. Here’s a way to plant seeds outside when it’s still too cold, and reuse containers besides!

Project Steps

Gather your materials and select the spot for your greenhouses.

First create two “greenhouses” by separating the two halves of the plastic container along the hinge using the multitool, scissors, or sharp knife.

You now have two “greenhouses.” The following steps should be repeated for each one. If any bubbles are smashed in, pop them back out. Peel off any labels, so that the seedlings can receive as much sunlight as possible.

Next, punch holes in the plastic container for water, garden stakes, and ventilation. The two holes on each end are for the stakes, the six around the middle are for water, and the two in the middle are for ventilation.

Look carefully at the water holes around the middle on your container. Depending on which half of the container it was from, there will either be little bumps, or little dips.

You want little dips. So, if there are little bumps, use something like the end of a pen to pop them out the other way, so that they are dips. (This will allow the water to drain down through the holes.)

Using an awl or the tip of a knife, make small, roundish holes at all spots marked in the diagram. The two for ventilation should be quite small, so as not to let too much air through. Note that the vent holes are in the biggest compartment – in this example it’s in the middle, but on others it might be by the side. Wherever it is, make the vents in the big compartment. The water holes should be bigger than the vent holes. The size of the stake holes doesn’t matter too much.

Now the greenhouse has been made; it’s time to prepare space in the garden for planting. Smooth out an area of soil bigger than the plastic container. If the soil is dry, water it – lightly damp soil is ideal.

Next, take the plastic and press it into the soil, wiggling it a little to help it sink into the dirt. Then lift it off – you should have a nice impression. The little hills are where you will plant the seeds. Using your hand or a shovel, pat down the hills firmly. Press the plastic in the dirt again, pat again – it should now be a firm impression with slight indentations.

Plant your seeds on the little hills, which will be underneath the bubble domes.

Water the newly-planted seeds.

Now set the greenhouse in place. Carefully place it over the seeds and stake it down.

To make your own stakes, take a metal coat hanger and cut according to the photo. Discard the hook of the coat hanger, and you will be left with two stakes. Bend them to the right spacing to fit through the holes, and stick ’em in.

Mound up dirt around the sides of the plastic container, where there’s a gap between the plastic and the soil. This will keep cold air out. Be sure not to cover the domes, though.

Next we will water the seeds. Pour water in each of the middle six dips. The water will drain through the holes and be absorbed by the soil. Thus, you don’t need to remove the plastic to water – just pour it on.

If you watered well, then the water which condenses on the domes will simply drip back down and water the plants effectively.

The watering holes should not be too big – if they are small, the water will drain slowly, and feed the plants better. If you made the holes too big, you can slow drainage by putting some dirt in the dips.

And that’s it – a mini greenhouse! It didn’t even cost anything. Leave it for a while, but don’t forget to water it! The photos here show one after 3 weeks. The seeds have sprouted, even though nighttime temperatures are still dropping below freezing.

When the weather gets warmer, I’ll transplant them into a garden bed. This procedure can be used with other shapes and sizes of plastic containers, too, though they don’t all work the same.

This one’s made from a papaya container. I have yet to see how it will work. So far, apple containers seem to work the best.

You can also increase the heat inside the domes by using a few small mirrors. Hot-glue them to wooden dowels and place them around the location of your greenhouse. Stake them down so that they reflect the sunlight into the greenhouse. This will give much-needed warmth through colder months and create condensation, giving the plants water.

Another great project from ThriftyRubbish!