Starting a Simple Hydroponic Garden


     This simple system was based on Dr. Kratky's research on hydroponic lettuce growing at the University of Hawaii. It is a non-circulating system where the fertilizer solution is kept in the growing tank all of the time. This method was further modified by independent hydroponic farmer, Mr. Alan Kuwahara, on the Big Island of Hawaii.


Unit #3: Monday, April 17, 1999

Friday, April 23, 1999


1. Preparing the Starter Plants

Two weeks before planting, you will need to prepare the seedlings for the hydroponic garden. In the Oasis Root cubes, place one lettuce seed and leave them in a dish of water for two weeks. In that time, the seeds should sprout into little seedlings. Be sure to always have the cubes in a dish of water. Don't let them go dry.

Oasis root cubes in a dish.


2. Choosing and Preparing the Container for Planting

     The best containers to use for hydroponic gardening are dark colored plastics. The darkness will keep algae from growing in the water. You will want to keep the algae away because an overgrowth of algae will take all the nutrients away from the plants. If you need to use a clear container, it is advisable to cover it with a dark plastic or tin foil.

     In selecting a container to do your hydroponics, you need to consider what type of plants you are planning to grow. Containers holding bigger volumes are good for long lasting plants or for plants which flower or fruit for a longer period of time. Wider containers provide more surface area to grow more plants or bigger plants.


Here are some sample of containers that can be used for hydroponic gardening.

Large and small rectangular containers

Juice container


     A dark colored five gallon bucket is ideal for growing a variety of plants because of its volume and surface area. For our first experience in hydroponic gardening, let us all use a five gallon bucket or something comparable in volume and surface area.

Five gallon bucket with cover


     You will need to have a cover for your container. The cover will suspend the plastic planting cones which your plants will be growing in. The cover of your hydroponic system needs to completely cover the surface area. If a cover is not available, a piece of plywood or foam board is fine. Prepare the cover by tracing the circumference of the plastic planter cones onto the cover and cut them out. Place four to six holes, evenly spaced around the cover. Be careful not to cut the holes to close to the rim on the container.

Cover used for black circular bucket


     After the holes have been cut, suspend a plastic tube in each of them. Your container is now ready for the nutrient water.


3. Mixing the Nutrient Water

     Plants in a hydroponic system need to be regularly supplied with nutrients. Because there is no soil from which the plants can get nutrients, you, the grower, need to take on the responsibility to provide all of the nutrients to the plants.

     In this method, the nutrients will be dissolved and added to the water in the container. There are a variety of premixed nutrient mixes now on the market. You only need to measure the appropriate amount and stir it into the water.

     The nutrients we will be using can be purchased from local retail garden shops. For a five gallon solution, you will need :

  • 2 slightly rounded teaspoons of Water Soluble Hydroponic fertilizer 8-15-36
  • 1 slightly rounded teaspoon of Epsom Salt (Magnesium Sulfate)
  • 2 slightly rounded teaspoons of Calcium Nitrate

Nutrients are purchased in bags.


     To make your fertilizer solution you will need a teaspoon and a cup to dissolve the fertilizer. Dissolve each chemical with water in the cup. After the granules are dissolved, add the liquid to the 5 gallon container of water. At strong concentrations, some of these chemicals will not mix or may cause a reaction and result in a white powder forming in the bottom of the container. This is why we are using a container or bucket which holds 5 gallons of water.

This is how to take a teaspoon of nutrient and pour it into a cup.


Now that you have the fertilizers measured and in the tank, you are ready to finish setting up your hydroponic system and transplant the seedlings.

Nutrients are mixed and poured into the large bucket.


     Place the cover with the plastic planting cones on the container and secure with duct tape. Place a root cube with the seedling into the cones. You will have to wait 4 to 5 weeks to harvest the lettuce.

Step 1: Place the root cube into a planting cone and secure with duct tape. Then put a seedling into the root cube of the planting cone.


Step 2: Place the planting cone into the holes of the cover.


Step 3: Put a planting cone in each of the holes in the cover.


When you are done, this is how it might look like.


     Keep your plants in an area where they will receive lots of sunlight. The lettuce prefers about equal amounts of direct sunlight and indirect sunlight. Keep your hydroponic system out of heavy rains. Water will get into the bucket and dilute the nutrient water.

Sample Hydroponic Lettuce Garden


As your lettuce is growing, you will need to watch for insects which will love to eat your lettuce before you do. Some of the insects include: grasshoppers, caterpillars, aphids, and slugs. You may need to watch for them and pick them off the plants by hand. Dealing with these pests will be focused on in another session.

Assignment #3:  

Setting Up Your Garden
  • Set up your 5-gallon bucket system with your lettuce plants.
  • Keep a journal of a typical plant in your hydroponic system. Your journal should include dates, growth (height and width of the plant) and detailed written observations. Drawing or photograph observations may also be included. Post your journal to your web site and keep updating it. Keep the journal going until time of harvesting (about 4-6 weeks).


Learner Outcomes
Student Template

Unit 1

What is Hydroponics?

Unit 2

History of Hydroponics

Unit 3

Starting a Simple Hydroponic Garden

Unit 4

Care and Maintenance

Unit 5

Pest and Diseases

Unit 6

Explorations into Plant Research

Unit 7

Independent Study:

Explorations in Hydroponic Gardening

Assessment Rubric


T3 Participants

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