Using the Kratky method to start or germinate seeds and transplant seedlings and sprouts

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Materials needed

  • Sponge for holding seeds or sprouts. I like the Park Seed biodome sponges, but you can use aerogarden sponges, rapid rooter plugs, rock wool, etc…
  • Container for holding the sponge. This has to let water/air through, small net pots work great, as do AeroGarden baskets. The AeroGarden baskets will fit perfectly in bottles that have a 1 1/2″ mouth.
  • Hydroponic nutrient solution – I use MasterBlend mixed with MgSO4 and Ca(NO3)2. More information on that here. There are many options, check with your local grow store or search on Amazon for something like DynaGrow. Mix about half the strength you’d normally use, but test first. For my Masterblend mix I use
    • 1.6 grams/gal 4-18-38 MasterBlend
    • .8 grams/gal MgSO4 (Epsom Salt)
    • 1.6 grams/gal Ca(NO3)2
  • Container for holding the nutrient solution. This can be anything really as long as it securely holds the net basket. You might half to carefully cut the top down to make it fit. You can also put these into flat lids for containers like totes. Just make sure the hole is just the right size to prevent the net basket from falling through.
  • Seeds or a sprout

Process steps

  1. Fill the nutrient container to the point where it touches the bottom of the grow sponge up to 1/2″ from the bottom.
  2. Place the seeds or sprout in the grow sponge and place it into the net basket/cup.
    • With seeds, just place them in the top of the sponge. If there is no indentation in the top, make one about a 1/4″ deep by 1/4″ wide.
    • With sprouts, cut the sponge halfway lengthwise. Spread it apart and place the sprout stem inside.
  3. Place the net basket in the growing container.
  4. Place the grow container under a grow light or outdoors if the weather permits.

Video of this process:

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How to grow lettuce using the Kratky method

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How to grow lettuce (and anything else) using the Kratky method of fill and forget non-circulating hydroponics.

Kratky grown lettuce

Materials needed:

  • Tote – The capacity needs to support a minimum of one gallon per plant. Also take into account you will lose some volume between the lid and net cups, unless have a tote with a raised lid. So, for a 10 gallon tote, six plants is good.
  • Lettuce seeds – You can get these anyway, lowes, walmart, etc… or amazon and ebay. They are very inexpensive, usually 1-3 thousand for two or three dollars.
  • Net cups – I like using the three inch net cups, but you can use whatever you have.
  • Hole saw – If using the three inch cups, a three inch hole saw (and arbor) cuts the perfect size. This is not necessarily true for the two inch cup and two inch hole saw, unless you get two inch cups with wide lids.
  • Grow sponges – This is to hold the seed until it germinates and sprouts. You can use peat based sponges like what AeroGrow and Park Seed sell, or rockwool. Rockwool needs to be pre-treated to lower the pH. I using the 6-0 refill size biodome sponges that Park Seed sells. These cost around 18.00 for 120.
  • Growing medium – This is to anchor the plant, you need something with good aeration. Clay pebbles (hydroton) or coco coir chunks work great.
  • Nutrients – Check with your hydroponics store, or search online. Most will work fine, like Maxibloom, Maxigrow, Dyna Grow, etc… I use a mix of MasterBlend, MgSO4 and Ca(NO3)2. More information on that here.
  • Grow light – T8 shop lights are fine. I personally like the Utilitech brand that Lowes sells, because the housing is so narrow that you can fit three side by side on an 18″ shelf. Try to get the daylight spectrum bulbs. CFL and LED lights work great too.


  1. Drill holes in the tote lid using hole saw. For three shallow 10 gallon tote I made six holes.
  2. Place sponge in the net cup and fill around it with grow medium, i.e. Clay pebbles, coco coir, etc…
  3. Place a small pinch of seeds (3-5) in the top of the sponge. It should have a small hole in the top for seeds
  4. Put the tote in place where it will stay and fill with nutrient solution. It should come up to a half inch to an inch from the bottom of the net cup. You can place an empty net cup in there to check the water level.
  5. With the lid secure, place the filled net cups in the lid.
  6. Turn on the grow lights and leave them on 24/7 until the sprouts come up and produce at least one set of true leaves
  7. Once the sprouts are strong enough to stand on their own, start thinning them down, eventually to just one per net pot. If there are several, this should not be done all at once.
  8. When the individual remaining sprouts have matured and have at least a couple sets of true leaves, put the light on timer and run 10-12 hours per day.

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Here’s a video of the process:

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Pepper Grow and Indoor Garden Update from 1/22/17

The following video shows an update on my 2017 pepper starts, as well as circulating and non-circulating hydroponic lettuce grows. Also my DWC Jamaican Hot Chocolate and self-watering containers housing the Thai Dragon and Tien Tsin peppers.

This year I’m starting my seeds directly in the AeroGardens or in my DIY AeroGarden that I made.

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