Episode-2626- Simple, Fast and Easy Kratky Hydroponics for Growing Food — 17 Comments

  1. I used to use the drill “mud” mixer and now I measure out the Master Blend components in a Dixie cup and put it in my blender with rain water to make a concentrate that I pour into my big bucket, then I use the mud mixer, it works so fast, I think I’m cheating!

  2. Two notes:

    1) in many areas, you can find blue food grade plastic barrels with clamp on lids cheaper than Rubbermaid trash cans, and they are a LOT thicker. Downside is they may let more light in.

    2) you can make threaded adapters work in the side of buckets if you use Teflon tape and a lock ring for metal electrical conduit (same threads) on the inside.

  3. If anyone wants an “easy button” for getting started, consider something like this and use grow plugs/sponges like the Rapid Rooters Jack recommends.

    This 72cell system can be used for seed starting, and growing greens to maturity as an “upside down” Kratky setup.

    1: Fill the tray nearly full with water/nutrient.  Include some (.5%-1% concentration) H2O2, it helps improve and speed germination plus gives your plants a sterile start.

    2: Drop in the rooting plugs.  Use all 72cells if you are strictly starting seeds.  Space them into something like a checkerboard pattern if you intend to grow to maturity.

    3: Place a seed in each plug.  You can use more seeds, but start with 1 per plug, the germination rate will be darn near 100%.

    4: Place the humidity dome on top and close the vents

    5: Optional:  Use the included heating mat if needed

    6: Place the whole thing under lights set to an 18/6 (light/dark) cycle as Jack recommends.  Note the lights will heat your rig, so don’t place them too close to the dome to avoid overheating.

    7: Wait 2-6 days for the first few seeds to sprout and open the dome vents when this happens.  Remove the dome completely after all/most seeds have sprouted.  At this time you can drop the lights closer to your seedlings if you want.  IMO they work fine from 12″-18″ so moving them isn’t strictly necessary.  Note that removing the dome isn’t strictly necessary either, some plants will do fine or better with the dome, but at some point it is just in your way and might crowd your plants.

    8: Keep an eye on your nutrient level, with the vents open or the dome removed your nutrient will evaporate.  Top up if needed to about 1/2 full.  Remember what Jack said about drowning the air roots, don’t overfill.

    9: Grow to transplant or harvest size.

    10: Enjoy!  Seriously, it’s easy and tastes great.



    • Totally gonna be item of the day today, funny to as yesterday I just realized how well rapid rooters fit 72 cell hex sheets. I am going to use them in my shallow flood tray with ebb and flow in my vert farm.

    • Regarding step 8 above…

      It may be counter intuitive but your plants will do better the lower you can keep the nutrient without going dry.  In this way it’s more like a Nutrient Film Technique (NFT) hydroponics.  NFT works great but it’s a dangerous game to play if you’re maintaining the nutrient level manually.

    • Regarding H2O2 and water levels…

      If you are not using H2O2, which dissipates and needs to be replenished every 3-4days, start with only 1/4 full tray and refill to 1/4 full or less.  Bottom line, your water levels will need to be much lower than I described above if you’re doing this without H2O2.

      • Uh. OK, forgot the H2O2. 5 days in & Arugula & Butter Lettuce are little bitty babies, but nothing from Tomatos, beans, peas or peppers (not that they’d normally be showing this early).

        Are they doomed (drowning)? Time to start over?

        What does ‘some’ H2o2 mean for people that measure things? A Tablespoon? =)

        When you say ‘lower’ concentration of nutrients to start, roughly where? (<EC 1600 I assume…using Texas VF).


        Thanks for any help, first time trying one of these seed starter thingys… =)

  4. Also an easy and small quantity start for nutrients, from Urban Farm, the makers of Texas Tomato Food (TTF).  A single quart of this stuff can make 64gallons of full strength nutrient and greens don’t need full strength.

    Note this general purpose Vegetable formula is probably better than TTF for greens.  TTF promotes flowering which is great for tomatoes, but undesirable for greens.

  5. Good episode!

    I’m having decent success growing lettuces and a few other things, Kratky style.  I’ve been starting seeds in a Parks Bio Dome and then putting them in Kratky tubs when they get roots coming out the bottom of the Parks plugs (I’m using the small ones).  I shove the plugs into 7/8″ holes in the Coroplast covers (like corrugated cardboard, but plastic).  The taper of the plug keeps about 1/2″ sticking out.

    I can quickly germinate a lot of plants in the Bio Dome so I haven’t done much starting directly in the Kratky.  Some of the starts go to my aquaponics system as well.

    I’ve been using Fox Farm Grow Big hydroponic liquid fertilizer (3-2-6) at a rate of 1.5 oz to 4 gallons of water.  It’s $12/pint at the local hydro shop.

  6. Do you have a link to the scale you mentioned to weigh out the grams of Master Blend?

  7. An idea I had recently, soda/beer cans for a container, especially those new 19.2oz beer cans. Use a can opener to open up the top (this works better than you might think and leaves no ragged edges if you do it right) and it fits a 2″ net cup.

    I’m going to try it with some smaller herbs like cilantro and basil.

  8. Do you have a link to those 24″x48″ NSF racks? I think I remember you mentioning you’d leave the link in the show notes. My google-foo is lacking, I can’t seem to find a good source for them. I like the idea of using those and would rather buy once, cry once.

    • I got mine from Home Depot because I needed it ASAP for the MEN Fair. Lots of people sell them and remember the much cheaper 18inch racks will support the flood trays, I did it for aesthetics mostly.

      • OK thanks, I see which NSF rack you got now. I was looking for a stainless one, thinking “rustproof”, and those are like $800 everywhere I looked. I picked up a set of the Burrina grow lights via TSPAZ and I am going to give growing my greens a shot. I think I’ll start with the Mason jar Kratky method and move on from there.