Kratky Method of Hydroponics

I was inspired by a youtube video by Bobby (mhpgardender) clearly showing the Kratky method of hydroponics. So I bought some tubs and proceeded to set them up.

If you are not familiar with the Kratky method of hyroponics, it differs from standard hydroponics in that it is a non-powered system. This method of hydroponics does not use air stones, pumped water or water changes. It’s a good system for just about anyone but especially for off-grid. I was attracted to the system for its sheer simplicity.  Simply leave a 1/4 inch air gap between the bottom of the pot and the water level. As the plants use the water, the water level will drop. If your crop, such as lettuce that takes only 30 days or so, finishes, simply replant the tub and refill with new growing solution. If you have a crop with a longer term such as tomatoes or peppers, replenish the water every three weeks or so. Here’s the diagram.

Kratky method of hydroponics
Kratky method of hydroponics

The first challenge I had was finding the net pots that are suspended in the water. Fortunately, we have three hydroponics stores in town which was somewhat surprising to me. We are a small university town of only 100,000 and only have two WalMarts. We are a very active farming community however. Maybe that accounts for having them.

Only one tub was set up to start. I had my husband use the 3 inch hole saw to cut six hols in the top of the tub.


Item Source Cost Tax Total
Tub WalMart $5.47 $0.35 $5.82
6 Net Pots Hydroponics Store $3.36 $0.21 $3.47
Fertilizer Hydroponics Store $15.22 $0.97 $16.19
Tomato Plant WalMart $3.34 $0.20 $3.54

Total so far is $29.02 and I have lots of fertilizer left over.

The standard growing medium is clay pellets, but mhpgardener mentioned that pea gravel, perlite or some other medium could be used as successfully. I had a driveway full of gravel so opted for the pea gravel. The gravel was washed and drained before putting it into the net pots. I carefully washed the growing medium off the purchased tomato plant and planted it in the net pot. This was a little interesting because I didn’t want to damage any of the roots if I could avoid it. I had to put the plant into the empty pot and dribble the pebbles around the roots. It was this process that gave me a little appreciation for the pebbles because the weight was very important in supporting the plant. Perlite would not have been as effective for a plant this size. By the way, the tomato is a grape tomato.

To add to my experiment, I wanted to plant some seeds to see if they would germinate in this setup. Planting seeds and especially small seeds in the pebbles would have been a waste of time. I needed something to suspend the seeds in the pots. I used paper toweling cut into strips about 1 inch by 3 inches, moistened the toweling and then folded it over the seeds and “planted” the assembly into the pots by simply putting a few pebbles on top of the toweling. I planted green beans, beets, cherry tomato and spinach. In the last space, I put a baby tomato that I dug out of the garden.

Kratky hydroponic method
The setup for my Kratky hydroponic method experiment

My experiment started on May 15th, 2013, exactly one week ago. Here are some photos of what’s happening today, May 22, 2013. I dug out one of the seed and saw that they are beginning to sprout, too.

Two tomato plants
Two tomato plants

The original grape tomato from WalMart and the little Delicious tomato from the garden both doing well after one week in the Kratky method tub.

The grape tomato
The grape tomato

The grape tomato is blooming like crazy. I’ll be thrilled when it starts to set fruit.


One of the three tomatoes planted in the third tub immediately after planting.

garden fertilizer
The fertilizer

This is the fertilizer combination I used yesterday. It is MaxiBloom 5-15-14. This was easy to figure out how to use since the directions are on the bag. It is 1 to 2 teaspoons per gallon so I went with the lower. I can always add to the solution later. The perfect solution is called Master Blend at 4-18-34. MiraclGro is 28-8-16. Waaaay too much nitrogen especially for a vegetable garden. So I still need to add some additional potassium.

Since this will be an on-going experiment at least for a while, I will keep everyone posted on the results.



Leave a Reply

%d bloggers like this: