Monday, November 28, 2011

An Inexpensive Hydroponic Method for Growing Salad Greens

Tatsoi, Radichetta and New Red Fire Lettuce

In Janice Crowl's book, Container Gardening in Hawaii, there are several pages devoted to growing hydroponic lettuce with a simple and inexpensive set-up. It's so easy and can be grown in just about any sunny spot, even indoors. This method was developed at the College of Tropical Agriculture at the University of Hawaii at Manoa  by Dr. Bernard Kratky.

Kratky's Hang-Loose Hydroponic Lettuce
Page 71

The following link is to a pdf written by Dr. Kratky:

All you need is:
1 gallon size plastic milk, juice or water container
Coconut coir, sphagnum peat, perlite or vermiculite
3 in. long net pot (1.5 in. to 3 in. wide)
1 tsp liquid hydroponic fertilizer 10-8-22 or a similar ratio
Aluminum foil, newspaper or a paper bag to cover the container

Sphagnum Peat, FoxFarm Grow Big (3-2-6), 1 gal. containers,
Coconut Coir, 3 x 3 in. Net Pots

Net pots could be made from recycled plastic yogurt containers or disposable plastic cups. Just cut or punch holes into the bottom and sides. I have a bottle of FoxFarm Grow Big liquid hydroponic fertilizer which has a similar ratio to the one recommended. Since the numbers are 1/3rd lower, I used 2 teaspoons per 1 gallon container and it worked great.

The 1.5 in. wide net pots fit into a cranberry juice container without alteration. When using a plastic milk, juice or water container place the net pot upside down over the opening and trace the pot with a china marker/grease pencil or other type of marker. Insert a knife above the line and cut about 1/4 in. above the line with a knife or scissors. Then fill the container with water up to 1.5 inches from the top.

 If you don't buy products in gallon size plastic containers they're easy to fish out of the plastic recycle bins at our Maui recycle centers. If you decide to use vermiculite, I recommend using only an OMRI product.

Radichetta Lettuce
at 40 days from seed

Hydroponic net baskets and liquid fertilizers can be purchased locally at Kula Hardware & Nursery or Ohana Greenhouse. I purchased the 3 x 3 in. net pots on ebay - $5 for 10 with free shipping. The sales person may recommend purchasing hydroponic air pumps - they aren't necessary and defeat the purpose of this affordable hydroponic method.

The best part is that you don't even need to water the lettuce - it grows so fast that additional water or fertilizer is normally not needed after the initial set-up.


  1. I'm intrigue, I like this idea, it might be something to try in spring/summer for us here.

  2. Hi Mac! I wish I had found this method when I first started to garden. It's so easy, inexpensive, low maintenance and the results are great. I think this method would work well indoors all year in a sunny window or under grow lights.

  3. And you don't have to remember to water! Great idea Jane ; )

  4. Hi Julie! This method is so easy. I just planted a variety of seeds to see what else I can grow this way.

  5. Hi there Jane! I just love this idea! It's a great way to do some growing inside. I'm going to have to give this a try.

  6. Hi Robin! I was so happy with the results I just had to share it!

  7. Aloha, Jane
    Mahalo for this post, and mahalo nui for Prof Kratky's PATENTED idea! I tried this idea before with kitty greens, but I figured this was old hat stuff back then, and my cat ate the grass faster than it grew. I have some sunny window space in my garage I can use before my household stuff comes in (really a slow boat to Taiwan, I believe). Makes me look at at various containers in a new light when I go to the store.

  8. Hi Pomaika'i! It does seem a little too simple but it worked out so well. I spend a small fortune on organic potting soil and fertilizer and this method cost me almost nothing. I've been calling it guerrilla hydroponics! Matson does seem to take forever especially if it's routed to Oahu before Maui. I hope your container arrives soon!

  9. Growing salad greens has just become easier with the tips the refreshing method that you shared here. Thanks to you, many homeowners can already enhance their gardens without having to break the bank.

    1. Really, after seen the images and read the whole article I also say that this is an affordable Hydroponic means for increasing greens veggies. I will definitely try to grow to follow to these information which you have been described.
      grow box

  10. If I germinate the lettuce seeds 1st in in the biosponge of a park's seed biodome, would I be able just transfer the sponge with the rooted lettuce in it directly to a neti pot; also if i did it this way, would I still need to add 2 planting mediums to the neti pot:coconut coir, vermiculite etc... also would bush beans, soy beans or Tom thumb peas work for this method? thank you and I love this blog. from yuklan

    1. Hi Yuklan! I don't know the answers to your questions. I've only used this simple hydroponic method. I was looking for something very easy that didn't require all of the equipment and space it takes for a typical hydroponic system. I just grew salad greens and I don't know if it would work for soybeans or peas.

  11. I'm so glad you're still answering questions so long after the original post. So here are my questions:

    1. Do you start/sow the seeds in the system or do you transplant seedlings that are already established?
    2. How much of the net pot needs to submerged in the liquid when you first start?

    This is pretty exciting! Mahalo!

    1. Hi Ikaika! I think it's easier to start seeds in the pot and then thin them to one. It probably works fine if you transplant small seedlings. The water level doesn't have to be precise. I tried to keep the level at 50% up the side of the net pot when I first plant the seeds. Then as they grow just keep the water in contact with the pot so the soil stays moist. It's really an easy method but if your weather is warm or windy be sure to check the water regularly as it will evaporate. It's best not to pull the net pot out of the water when the seedling begins to develop roots. I just opened the aluminum foil to check the water level. Good luck!!

  12. Aloha Jane,
    I also started the exact same way, with the Kratky method. The man was an absolute pioneer for horticulture in Hawaii. I still start my seeds this way, but then put the drip cups in a rain gutter system with a small fountain pump. I think the pump was $8 at lowes. Fox farms has worked well for greens and seedlings, but had to upgrade for my tomatoes and peppers. U.H. has a great seed program too. The Manoa lettuce is awesome.
    Have a great day. Aloha,

    1. That's cool - I'm still using this basic method. I'll have to check out their seed program. Mahalo!