A DIY Kratky Container Series Using Recycled Materials Part 4: Assembling the Top Plate and Preparing for Planting

In Part 1, we introduced the basic materials you’ll need. Part 2 walked through how to create the Base Housing for your growing medium. Part 3 focused on preparing the nutrient solution containers and the seed-starting dome.

Now in Part 4, we’re putting it all together by creating the top plate—the crucial part that connects your base housing to the nutrient container, supports the plant holders, and stabilizes the system.

Step 1: Choosing Your Pie Plate

We’re using either a small or regular-sized aluminum pie plate as the top of the container.

• Small pie plate: Fits snugly inside the rim of most 4L containers, making it easier to mark slit locations for the tabs.

• Regular pie plate: Provides more surface area for added stability but needs a bit more precision when marking and cutting.

Step 2: Marking and Cutting the Slits for Tabs

Place the top of the nutrient container (with tabs facing down) into the pie plate.

For the small pie plate:

1. Align the base of the container in the center.

2. Use a marker to place a small dot or line at the center of each of the 4 tabs.

3. Cut a ¼-inch slit just outside each mark—this is where the tabs will slide through.

4. Make sure the slits are centered and be very careful if using an X-Acto knife—they’re sharp and can create jagged edges.

   • If you don’t have a cutting board, press gently into the pie plate without cutting all the way through to your work surface.

For the regular pie plate:

1. Center the container again.

2. Mark the outer edge of each tab location.

3. Cut longer slits (slightly longer than the tab width) to allow easier insertion.

Once your slits are made, carefully insert the tabs through the pie plate. You may need to wiggle them a bit to get them through—just be mindful of the sharp edges. Once inserted, the tabs will stick up above the pie plate and help support the dome.

Step 3: Placing the Seed-Starting Dome

With the tabs inserted and standing up:

• Place the dome (top of the 4L bottle from Part 3) over the tabs.

• The tabs should sit inside the dome, holding it in place and creating a snug, stable environment for germination.

This setup allows for improved humidity and warmth, which helps with seed germination, and you can easily lift the dome to mist the seeds a couple of times a day.

Step 4: Marking and Cutting Holes for Plant Holders

Now it’s time to create the holes in the pie plate for the three small containers (from Part 2) that hold your growing medium.

Here’s how:

1. Remove the bottle caps from the small containers.

2. Place the containers upside down on the pie plate so the wide ends are touching the surface.

3. Use a marker or pencil through the open tops to mark the center point of each container.

4. Once you have the 3 marks, use a 4L bottle cap as a stencil to draw a circle around each one (centred).

   • Tip: If you cut out the center of the cap, you’ll be able to see your mark clearly and ensure it’s properly centred.

 Cutting the holes:

• Use an X-Acto knife to start the cut in the center of each circle.

• Insert scissors into the slit to cut out the full circle.

• The holes should be big enough for the small containers to sit about halfway into the pie plate.

This design allows:

• The growing medium to stay moist

• The plant roots to access the nutrient solution below

• Enough space for the solution to nearly fill the container

 Step 5: Final Assembly

• With all the holes cut, insert the three small containers into the holes in the pie plate.

• Slide the tabs through their slits and place the dome on top.

• You’ll now have a complete setup with space for three plants, a humidity dome, and a stable top plate.

You can see in the photos (as mentioned) how the setup looks with and without the dome. The dome is used during germination. Once the seeds sprout and are strong enough, you can remove it.

Coming Up Next:

In Part 5, we’ll cover:

• Adding the growing medium

• Why you may want to paint or decorate your containers

• Tips for personalizing your setup for function and beauty

Then, we’ll move into building a larger setup using a 15L water jug, perfect for growing multiple plants to full maturity and seed production.