I am trying to grow honey dew at my balcony using the Kratky method. I have been using A&B solutions for the nutrients. It doesn't seem to work as the flower after being pollinated has small fruits. But it never grows any further. What type of nutrients should I use? And how much water? – Best regards, Ann P.

By Lynette Morgan | Last updated: March 10, 2022

hydroponic melons

If you are using a good quality A and B nutrient product, then it is unlikely the nutrients are the cause of the lack of fruit set and development, unless you are also seeing major deficiency symptoms such as leaf yellowing, chlorosis, leaf burn, etc. at the same time. Melons are notorious for failing to set early fruit, particularly on young plants, even after you have carefully pollinated the flowers and this is not usually a nutritional issue. The first step with identifying the problem would be to check your pollination method.

Melon flowers need to be hand pollinated to ensure fruit set. This process involves collecting pollen grains from the male flowers and brushing these on the insides of the open female flowers. Female flowers can be identified by the small green melon at the base of the flower. Pollination should be carried out daily and each flower pollinated two to three times. It’s normal for not all hand-pollinated flowers to set fruit, when this occurs the young melon will yellow and drop from the plant. Also check your growing conditions are suitable for pollination and fruit set; temperature, humidity, air flow, and most importantly dissolved oxygen in the nutrient solution all play a role in this process.

With melon nutrition the reason why the ratio of nutrient elements — in particular nitrogen and potassium ratios — change through the plant development stages to is simply provide what the plant wants to take up (melon fruit contain a lot of potassium, so this needs to be supplied during the fruit expansion stage after fruit set has occurred). The ratio or concentrations of elements and changes to these do not trigger or cause fruit set — these are much more influenced by the environment and general plant health.

An example of general-purpose melon nutrient formulation is given below. This is made up into two A and B stock solutions of 2.6 gallons (10 liters) each, which are then diluted 1 in 100 with water to give the working strength nutrient solution. You would need to obtain all the fertilizers given below and weigh them out to make up your own A and B concentrates.

Melon Fruiting Formulation (RO water)

Part A — 10 litres of water

  • Calcium nitrate 571 grams
  • Potassium nitrate 414 grams
  • Iron chelate (10% Fe) 50 grams

Part B — 10 litres of water

  • Potassium nitrate 414 grams
  • MonoPotassium phosphate 350 grams
  • Magnesium sulphate 976 grams
  • Manganese sulphate 8 grams
  • Zinc sulphate 1.1 grams
  • Boric acid/Solubor 3.9 grams
  • Copper sulphate 0.3 grams
  • Ammonium molybdate 0.1 grams

Dilute equal amounts of A and B at a rate of 1 in 100 with water, this will give an EC of 2.4 for fruiting melons.

Lynette Morgan
Suntec International Hydroponic Consultants

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Hydroponics Plant Types Fruit

Written by Lynette Morgan | Author, Partner at SUNTEC International Hydroponic Consultants

Profile Picture of Lynette Morgan

Dr. Lynette Morgan holds a B. Hort. Tech. degree and a PhD in hydroponic greenhouse production from Massey University, New Zealand. A partner with SUNTEC International Hydroponic Consultants, Lynette is involved in remote and on-site consultancy services for new and existing commercial greenhouse growers worldwide as well as research trials and product development for manufacturers of hydroponic products. Lynette has authored five hydroponic technical books and is working on her sixth.

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