How to Use a DIY Self‐Watering Tub for Seed Germination

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Seed germination is easier with a self-watering tub. Reliable seed germination depends on uniform moisture in the potting soil and the proper temperature for the seed being grown. A DIY self-watering container, with a large fabric wick, will maintain a uniform moisture level in the potting soil. Recycled food containers work great for seed germination and the growth of flower or vegetable transplants. This wikiHow will show you how to prepare your own!

Part 1
Part 1 of 2:

Choosing and Sowing Seeds

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    1
    Select your favorite seed varieties. Purchase seed of the flowers or vegetables that you wish to grow, or use seed that has been saved from the previous year.
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    2
    Obtain several food containers to plant your seeds in. If you wish to use smaller containers, use fruit, yogurt or pudding cups. For larger containers, try saving potato and meat containers. Clean out each container thoroughly before use.
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    3
    Cut 2-3 holes of approximately 0.5 inches (13 mm) in the bottom of each container with a drill or a utility knife. These holes will allow direct contact between the potting soil in the container and the wick. This will maintain a uniform water content in each container during seed germination and growth.
    • The wick is absorbent fabric used to transfer water from the supply to the potting soil. One end will be submerged in the water, and the other in contact with the potting soil of the plant container.
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    4
    Fill each container to about two thirds full with high-quality potting soil.
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    5
    Place 1-3 seeds in each small container and a few more seeds in the larger containers. Arrange them in rows so they are easier to replant later on. Then, cover the seeds with another layer of potting soil.
  6. 6
    Water the seeds and container from above or below. To water from the bottom, place the containers on a plate or tray. Pour water to a depth 13 mm (0.5 inches) into the tray. Allow the containers to soak up water for about 30 minutes.
    • Alternatively, use a light mist from a spray bottle or a hose to water the plants from above. Apply water 5 times over 30 minutes.
    • While the containers are soaking, you can begin to set up the self-watering tub.
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Part 2
Part 2 of 2:

Preparing the Self-Watering Wicking Tub

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  1. 1
    Obtain a plastic storage tub with a lid. This tub should be 3-10 gallons (12-40 litres) in capacity with no drainage holes. Alternatively, purchase a new storage tub and lid from a hardware or department store. Make sure the tub is clean before using it.
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    2
    Cut a slit of approximately 5 inches (12 cm) long and 0.25 inch (5 mm) wide in the lid of the tub. You can use a utility knife, manual keyhole saw, power jigsaw or oscillating saw.
  3. 3
    Drill a 0.75-1 inch wide (2-2.5 cm) hole near the side of the lid. This will be used for adding water to the self-watering tub.
    • Consider using a waterproof plug, tape or fabric to block up this hole. This will keep mosquitoes out of the water in the tub and prevent them from laying their eggs. Alternatively, you can scatter a mosquito dunk in the water reservoir. This will kill mosquito larva for up to 30 days. [1]
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    4
    Make a small hole in the side of the tub, about 1 inch (2.5 cm) below the top. Use a 0.25 inch (5 mm) drill to create the incision.
    • This is an overflow hole to keep the tub from becoming overfilled with water.
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    Use a clean, new or used towel or washcloth: this is the large fabric wick. The towel (wick) should be 12-30 inches (30-75 cm) in length and width.
  6. 6
    Feed the saturated towel through the slit you drilled in the lid of the tub. Make sure most of the lid is covered by the towel and 6-8 inches (15-20 cm) of the towel hangs into the water in the tub. If necessary, you can fold the towel and then feed it through.
    • Artificial fibers last longer than cotton as a large fabric wick.
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    Cover the exposed towel on the lid of the tub with a sheet of tightly-woven fabric to prevent roots from growing into the towel. You can repurpose an old skirt lining for this, or use an alternative to protect the wick beneath.
    • In the photo, the yellow towel is the large fabric wick and the black fabric is a tightly woven fabric called Hang-Loose. [2]
    • If no fabric is used, simply cut the roots of the transplants free from the wick when it’s time to move them to the garden or containers.
    • Weed-X, a fabric used in landscaping, will also work well to control the plant roots.
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    8
    Place the pre-filled containers on top of the fabric wick. Water the potting soil with a light mist from a spray bottle or hose a few times. This will establish the wicking connection (transferring of water) between the water in the tub, the wick (towel) and the potting soil in the container. The wick will keep the potting soil uniformly moist throughout seed germination and transplant growth.
    • Add water to the tub every 5 to 10 days (7-8 is around average) to aid seed germination and growth.
    • At any time, if the potting soil seems too dry, water it from the top to re-establish the wicking connection.
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    9
    Manage seed germination temperatures. Temperatures must remain between 65 and 75° Fahrenheit (18-24°C) at all times for successful germination. Use the lower end of this range for cool season plants, e.g., lettuce, cabbage, broccoli, pansies, and dianthus. Use the higher end of this range for warm season plants, e.g. tomatoes, peppers, squash, vinca, and zinnias.
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    This will ensure your seedlings grow to be healthy. If you wish to grow your seedlings indoors, your tub should be placed 8-12 inches (20-30 cm) below LED or fluorescent lamps.
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    11
    Use water-soluble fertilizer for the transplants. Apply water-soluble fertilizer to the seedlings after 2 to 3 weeks. Use only 0.25 to 0.5 times the manufacturer’s recommended rate every 7-10 days. The fertilizer can be applied directly to the potting soil, or added to the water in the tub.
  12. 12
    Keep your seedlings outdoors in the Sun for around 7 days before planting them in the garden. This is known as “hardening-off” and acclimatizes them to cooler temperatures, lower humidity and increased air movements. This way, the plants will be better able to handle the rigors of the garden environment. [3]
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      References

      1. ↑ https://www.hooksandlattice.com/self-watering-container-gardening-guide
      2. ↑ https://publications.ca.uky.edu/ho-84#
      3. ↑ https://www.rhs.org.uk/prevention-protection/hardening-off-tender-plants

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