Hydroponic Nutrients with Soilless Medium

It's quite difficult for me here in Vietnam to buy fertilizer product, but I did manage to buy some Dutch Master Potash+, only later to find out it was for use hydroponically. Will this be OK to use in my soiless potting mix? I grow fancy Hibiscus on my roof top in Nha Trang; or should hydroponic products only be used in a water growing medium?

In fact, I am a little confused as to what hydroponic means. I think it means growing plants in water and not soil. I hope I have not wasted my money, and thanks for any advise you can give me.

Answer: When people mention hydroponics, they are referring to any system (or method) by which plants can be grown in which they receive all of their nutrients through the supplied water (including hand watering a soilless medium with hydroponic nutrients). This makes it very important to know the nutritional requirements of your plants, as well as how to maintain your nutrient solution properly.

All plants require water, proper nutrients, and the presence of Oxygen at the root level. In a hydroponic system the growing medium contains no nutrients, and is there mostly for physical support and for its ability to keep the roots moist. So, the short answer to your question is that it should be perfectly fine to use hydroponic nutrients with your soilless mix....as long as the nutrients satisfy ALL of your plants nutritional needs.

Mostly, plants require Nitrogen, Phosphorus, and Potassium. These are the three major nutrients that make up the N-P-K numbers displayed on any fertilizer. In addition, most plants require the presence of secondary nutrients (Calcium, Magnesium, Sulfur, and Iron) and very small amounts of many micro-nutrients (possibly as many as 42 different micro-nutrients!).

To complicate things a little more, the nutritional requirements of many plants change as the grow older, and as they switch from vegetative growth (in the Summer) to flowering (in the fall, usually). More specifically, plants require more Nitrogen during the vegetative stage and more Phosphorus and Potassium during flowering. This means (for most hydroponic gardeners) they need some way of adjusting the N-P-K ratio of their fertilizer. The way this is done is by using "two part" or "three part" hydroponic fertilizer programs, where the ratio of the different parts can be changed as needed.

Another way is to use one fertilizer as a "base" fertilizer and use a fertilizer additive (nutrient additive) to increase the Phosphorus and Potassium content as needed (for example). This brings me to your hydroponic nutrient, the Dutch Master Potash+. This is a product that is designed to be used as a nutrient additive to boost Phosphorus and Potassium levels in your fertilizer recipe. Unfortunately, it does not contain any Nitrogen. Also, I don't believe it contains any of the secondary nutrients or micro-nutrients (I could be wrong- you will need to read the bottle carefully and determine this).

If fertilizer purchases are hard to come by, than you may want to consider trying to make your own recipe. Properly made compost makes an excellent compost tea fertilizer. While the exact nutrients in compost tea will vary depending on how the compost was made, it will very likely contain some amount of each of the secondary nutrients and many of the micro-nutrients that your current fertilizer is missing. Aged cow or horse manure can be added to the compost tea to add the very much needed Nitrogen that your fertilizer is missing. Soaking alfalfa hay in water also produces a solution high in Nitrogen, but it stinks....I mean REALLY stinks (just a fair warning).

The compost, manure, and any other products your want to try in your tea (such as liquid seaweed or kelp meal- both packed with micro-nutrients) should be placed in a sock or pillow case and suspended in a 5 gallon bucket of water. Jiggle the sock every once in a while to help the nutrients into the water. Allow 24 to 48 hours to brew. When your plants begin flowering, a small amount of the Dutch Master Potash+ can be added to the solution to ensure heavy flowering. You will have to experiment a little to get your dose right and to make sure there are no nutrient deficiencies, but this method can be both simple and very effective (not to mention inexpensive).

The only thing I would be concerned about would be the pH of the solution before you water it in. Having the pH wrong can produce symptoms in your plants that appear to be nutrient deficiencies even though all of the required nutrients may be present (but unavailable at that pH). PH test kits can be purchased quite cheaply (around $4.00 for the cheap kind here in the US), although this may be another hard-to-get item where you are located.

The ideal pH for most plants is around 6.2. This is the pH at which the greatest number of nutrients are available to the plants. If the pH of your solution is off, you will either need to try a slightly different fertilizer recipe or else purchase a bottle of pH UP or pH DOWN (depending on your needs). I sure hope this helps you out, and Happy Growing!

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May 11, 2010
Gardening in Vietnam.
by: Anonymous

Thank you so much, especially your very clear information as to what Hydroponic actually means. I just need to find somewhere buy those pH strips now and I will be all set. Thank You.

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Hi everyone, Jason from Jason's Indoor Guide here. When I got started with hydroponic gardening more than 24 years ago, my first garden used rockwool cubes and B.C. Nutrients....and I remember thinking to myself yeah, sure, there may be a lot of advantages to gardening with hydroponics, for example there are very few pest problems, therefore very little pest control, no weeding, no plowing or tilling the soil, no soil testing or having to add things into the garden soil, no watering the garden....but for someone who just wants to grow their own vegetables and have more control over their food supply and the quality of the food that they eat, the cost of constantly having to buy grow media and hydroponic nutrients makes this an expensive hobby for most people...

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I suppose when you take into consideration how much money you save NOT having to buy food at the grocery store, it is surely cheaper to grow your own food hydroponically even with the cost of high quality nutrients. Nevertheless, I didn't have a whole lot of money to work with and I needed to make my efforts as affordable and effective as possible....and in the last 24 years I HAVE learned a thing or two!

As you browse through Jason's Indoor Guide, you will notice all of the systems that I use personally are homemade systems. As I got 3 or 4 years of experience under my belt, I quickly adopted a preference to standing water systems and systems that use expanded clay pellets or lava rock, because the media is re-usable and it eliminates a huge operating expense. So once a hydroponic system is built, garden maintenance is minimal- check and adjust the nutrient solution daily, and to change it completely every 2 weeks....and the biggest operating cost is the hydroponic nutrients. (and the electric bill, lol)...

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And, regarding the cost of the nutrients....I experimented for about 3 years with making different compost teas and nutrient teas, but there is still a lot of expense $$$ associated with making high quality nutrient teas....like kelp meal, liquid seaweed, rock dust, bat guano, un-Sulfured molasses, worm castings. You can eliminate a lot of this expense by becoming an expert at making high-quality colloidal humus compost, and use your properly made compost as the basis of your hydroponic nutrient solution.

Unfortunately, I have been gardening for over 24 years and I have only just recently mastered this difficult skill....and even then, only because I happened to find a very easy to follow, high quality technique and decided to follow the instructions to the letter. I produced more high quality compost in just one week than I was able to use in a whole year! If you can master the technique, I highly recommend it. It is one of the top 3 things you can do to increase the productivity of your food production efforts, while at the same time decreasing the amount of effort required to grow all of your own food, and decreasing the total cost of operating your food production system.

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