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:

A Simple Hydroponic Growing Kit for Short-Term Vegetables

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.