Hydroponics Tutorial: Grow your own food easily

Anyone in New Zealand can grow delicious courgettes, tomatoes, cucumbers, capsicum, strawberries and more, even in the tiniest backyard. Growing hydroponic fruit and veggies can be simple – requiring little-to-no maintenance, or back-breaking weeding.

You’ll need:

Cucumber do very well in Hydroponics
Preparing courgette eedlings to move into the drums


Inside a greenhouse or outside on a deck: Ideally you need a spot that’s covered from direct rainfall, sheltered from strong winds, and gets at least 6 hours of direct sunshine.

What you need to know:

We use a hydroponics method developed by Bernard Kratky – the Kratky method*.

Kratky method: The plant takes up water and nutrients through the roots in the nutrient-water solution. Above the water, the plant develops air roots to take up oxygen. IMPORTANT: the roots should not be entirely covered or the plant will drown.

As the plant grows it absorbs water and nutrients, which will fall as it’s used. As the nutrient and water solution falls, the plant develops air roots which will provide the plant with oxygen.


  1. Rinse out the drum, but avoid any drum/container that previously held harmful ingredients i.e chemicals/poison.
  2. Drill a hole in the top of the drum, which is the right size to fit your netting cup.
  3. Place the drum in the location you’ve selected to grow your plants.
  4. Fill the drum with water so the plant’s roots have contact but are not totally covered. Rainwater is best, but if you use tap water let it sit for two days so most of the chlorine evaporates.
  5. Dissolve/dilute your hydroponic nutrients in a separate bucket, before filling into the drum – follow the dosage instructions on the packaging of Herbi’s hydroponic nutrients, or Herbi’s website
  6. It’s not necessary, but you could check the nutrient levels in the water with a ppm meter (this measures the parts per million of nutrient concentration in water. You can get one for approx $7 on Trademe). Let your mix sit for a day and measure a second time as values can increase overnight. However, If you follow the instructions and recommended dosage on Herbi’s packaging then you don’t need to use a ppm meter, although it can be nice to double check.
  7. Fruiting plants like strawberries, tomatoes and particularly capsicums love high nutrient concentrations. Please google for i.e. “EC ppm hydroponic tomatoes” for details, or contact Herbi.nz for individual feeding charts: chat with the Herbi team here
  8. Before planting your seedling, rinse out the roots very intensively so any soil is removed, but without harming the roots! Ideally, your seedling would be germinated in a hydroponic medium.
  9. Place your seedling into the netcup taking care that the roots reach the water surface. If needed, you can cut a wider opening in the drum and pull the roots through until they are touching the water. We like to have the net cup 1-2 fingers high in the water. This way the germination medium touches the water and gets soaked. Fill up the net cup with clay pebbles. The clay pebbles will give the plant stability but also covers the water from direct sunlight. This is important to avoid algae growth.

IMPORTANT (1): If you need to add more water to the drum while the plant is growing, only add a little amount at a time. If you fill the container to the top then the plant would drown. The air roots need to stay above water to uptake the necessary oxygen.

IMPORTANT (2): Hydroponic plants can be more susceptible to pests and disease as they don’t have the natural resilience cover that they’d have if grown in chemical-free living soil. Monitor your hydroponic plants regularly for possible infections, particularly white flies and aphids which can occur, as well as fungal diseases like powdery mildew, especially at the end of the season. Please avoid any chemical pesticides and fungicides – you want to grow healthy food to eat! Look online for homemade harmless pest mixes, or use our all-natural Herbi ZYMES – Pest Control All Natural. Spray your plants once a week in the evening hours for prevention or follow the instructions to remove an existing infestation. Herbi ZYMES Pest Control is all-natural, but kills all soft-bodied insects and is harmless to bees and ladybirds.

Which fruit and vegetables to grow in hydroponics?

Courgettes, Tomatoes, Capsicums and Strawberries have grown amazing for us in hydroponics – surprisingly one of our best fruits has been Cape Gooseberries. They grow vigorously and are constantly delivering delicious and healthy superfood fruits.

The same system also works for lettuce, although you don’t need a blue drum. A little (light-tight) 20L container with a lid would do the job. Unfortunately, in summer it gets too hot for lettuce – particularly because the nutrient solution heats up and gets too hot.
If you want to grow tomatoes please decide before planting if you want to grow a determinate or indeterminate kind. The indeterminate kind will require constant pruning and space to grow the stem, or it will turn your hydroponics into a tomato jungle.

What you don’t need:

  • More water: the water in the drum usually lasts for the entire season.
  • Additional hydroponic nutrients: 200l hydroponic solution in a drum usually lasts for the entire season and is simple – just pour the recommended dosage and add water.
  • Lots of space: You only need the space the blue drum takes up, inside or outside.

Happy Growing! 🙂

*Kratky Method on Wikipedia: “The Kratky method is a passive hydroponic technique for growing plants suspended above a reservoir of nutrient-rich water.Because it is a non-circulating technique, no additional inputs of water or nutrients are needed after the original application, and no electricity, pumps, or water and oxygen circulation systems are required. The Kratky method has applications both for commercial food production and as a small-scale and low-maintenance technique for home growers. It has been described as “the simplest hydroponic system.”


  1. Makere Aroha

    Ive just watched your interview on Breakfast. I just want to know what the net cup is and where you get one of those please.
    Thank you for your gift. I am sure many youong people will be interested. I will be forwarding your website on.

    Warm regards

    1. Frank (Herbi.nz)

      Hi Makere,
      thank you so much. We are glad that you liked it.
      The pots are indeed currently hard to get. I’ve had a look online and on several shops the 3-inch pots were sold out. However, sometimes the wicked pots work too. You just need to take care that the pots enable enough water flow and the holes are big enough to let the roots grow through them. In times I ran out of net cups I just used common party cups and melted holes with a soldering iron into it. 😉
      Good luck, and feel free to get in touch using our chat on the website if you have any other questions.
      Happy Growing 🙂

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