Starting and Growing Seeds in Your Indoor Hydroponic Garden

Starting and Growing Seeds in Your Indoor Hydroponic Garden

So you've done the hard part of buying and assembling your vertical garden.  (If you haven't done that yet, check out our article about How to Build an Indoor Hydroponic Garden.)  Now it's time for the fun part!  In this article, we're going to be discussing how to start and grow seeds in your garden.

For our purposes, we're going to be using the Kratky growing method.  There are a lot of different hydroponic growing methods, but this one in particular is the easiest for beginners as it requires the fewest inputs (no pumps/pipes/airstones/etc.).  Most hydroponic systems require pumps or airstones to oxygenate the water/nutrient mix so that the plant roots can receive oxygen they need to survive.  In Kratky systems, as the roots pull water from the reservoir, an air-gap develops between the bottom of the plants and the water.  It is from this air-gap that the plants can receive their oxygen.

Now that we know a little bit about the system we're using, let's get to starting some seeds!

Starting the Seeds

1 - First, make sure you've got your seeds!  The methods we're using are specifically tailored to leafy-greens (fruiting/rooting vegetables require more intense infrastructure than what we're using).  We personally use seeds from West Coast Seeds, but we've also used big-box store seeds and they work fine here too.

2 - Get the fertilizer mixed.  If you're using Masterblend like we do, this requires measuring out the ingredients by weight and mixing them one-at-a-time into a large reservoir.  For the purposes of my garden, I'm filling a 5 gallon bucket halfway (to make mixing easier) with water from the tap.  If you are concerned about your water pH, you can use a pH reader and adjust accordingly using a pH Up/Down kit.  (We have found that if you use municipal water, this isn't a big concern).  

Then, using a small scale, in the following order add and mix: 12 grams of Masterblend mix, 6 grams of epson salt, and 12 grams of calcium nitrate.  Each ingredient is mixed into the water one at a time (or else it won't properly blend).  

Once your bucket of water/fertilizer is thoroughly mixed, grab your TDS reader (if you have it) and use it as you begin to fill the bucket up the rest of the way.  I like to keep the measurement somewhere between 630 and 730 ppm so I stop the water when it gets to that point.  

Set the bucket to the side to use again later after your seeds have been sown in Rapid Rooters.

3 - Set up a sturdy, flat area to do the seed-sowing.  We use our dining room table, set up with the following things:
- The number of seeds you wish to sow
- Net cups for the amount of plants you're going to start
- Rapid Rooters for the same amount
- A cup of water
- A toothpick (we use a plastic floss pick)

4 - Sow your seeds, one at a time.  Take one seed and one rapid rooter.  Tear a corner off the rapid rooter to use as cover for later.  Place the seed in the center of your palm and dip your toothpick into the cup of water.  Bring the toothpick to your palm and gently touch the seed to the toothpick where water has beaded.  The seed should stick to the bead of water.  

Now carefully place your seed into the side of the hole of the rapid rooter at the appropriate depth (with lettuce seeds that's ≈1/4 inch).  Then carefully place the torn corner over the hole to cover.  Gently place the sown seed/rapid rooter into a net cup.  Repeat for however many plants you want to start.

5 - Place net cups into the panels seated above your reservoirs in your garden.

6 - Fill your reservoirs until the fertilized water reaches halfway up the net cups. (I usually keep at least one of the net cups empty during this step so I can see the water level clearly.)  This water level should keep the rapid rooters moist to encourage germination (and not require you to constantly water them).

7 - With the fertilizer mix halfway up the net cups, the rapid rooters should be adequately moist for seed growth, but I still do a very light spray from above to ensure moist growth-medium for the seed (at least for the first few days).  But other than that, just be patient, and before you know it, those seeds germinate and start poking out from the rapid rooters!

8 - As the seeds grow, the moisture from the reservoir will begin to transpire through the plants' leaves and an air gap will open between the bottom of the rapid rooters and the nutrient water line.

9 - Hydroponics are not as forgiving as soil when you forget to water.  The plants die quickly if they run out of water, so keep a close eye on the water!  If the nutrient gets less than a half-inch deep, I usually refill it to ≈3/4 of an inch.  You want to be careful not to overfill, because the roots in the air gap are not accustomed to constant moisture and they may drown and die.  We want to maintain that air gap so the plant can get the oxygen it needs in this environment.  

10 - Grow to the appropriate harvest period (or when you just can't wait anymore).  Some greens, like lettuce, will survive a cut-and-come again method, while others require more strategic harvesting/trimming methods for a prolonged harvest period.  Your seed packet should have a lot of that information, and if not, YouTube has an endless amount of helpful information for pretty much anything you may be interested in growing!

11 - At some point, the plant will stop producing.  When this happens, empty out the net cups and repeat the process!

If your seeds need more warmth and are having difficulty germinating:

This is where our handy-dandy seed-starting station and heat mat come into play.  Instead of putting your recently-sown rapid rooters directly into the net cups, place them instead in your well-watered seed-starting station.  

When placed on top of the heat mat, the domed-roof will maintain warmth and moisture, creating an optimum environment for seeds that require higher moisture/temperature than the ambient environment where your hydroponic garden is placed.  

After the seeds have germinated, we immediately place the rapid rooters into the garden, and most flourish.  Some people like to wait until the first set of true leaves appear, but with this system we're looking for as-easy-as-possible, so the sooner we move them the less complicated it gets.

We hope this was helpful!

Good luck as you venture into the new and exciting world of hydroponic growing!  This is just a crash-course to get you started.  There's a whole world out there waiting to be explored if you decide to take this to the next step.  Good luck!