Garden & Greenhouse


Nutritional Supplements for Hydroponics and Soil Based Gardens

Posted March 21st, 2008 by Garden & Greenhouse in

Just like animals, plants require a wide variety of nutrients, in addition to pure water, to function at their best. For soil based gardens the goal should be to have soil that not only performs the mechanical functions of providing gas exchange, drainage and support, but that helps to provide the nutrients needed for healthy plants. Well developed compost can provide nutrients that are hard to replicate with other fertilizers and supplements. That said, regular fertilization with quality products can certainly increase plant growth and production. With hydroponics, all plant nutrients must be supplied in the nutrient solution or through foliar feeding. This article will discuss some promising nutritional supplements for plants that go beyond the primary nutrients and list a few recommended products in each category.

Micronutrient Supplements

Fortunately, the better fertilizer companies have added micronutrients to their products in addition to the three primary plant nutrients: nitrogen, phosphorous and potassium. For those not using fertilizer, or using a blend that does not contain micronutrients, there are some good products formulated to prevent and correct micronutrient deficiencies. Micronutrients can do some great things for the soil including influencing proper soil pH, improving soil structure and water retention and positively influencing the level and activity of beneficial soil microorganisms. They also aid plants to better use primary nutrients. Because of these benefits, and particularly if one has experienced problems associated with micronutrient deficiencies like blossom end rot or tip burn, it may be good insurance to experiment with micronutrient supplements.


B Complex vitamins have been shown to help plants overcome stressful growing conditions, increase nutrient uptake and increase disease resistance. Some formulations may also contain other vitamins, amino acids and minerals. The use of B vitamins may be of most benefit when transplanting and/or during early season root formation.


Silicon (Si) is abundant in most soils. It is readily taken up by plants and is often present in relatively high concentrations in plant tissues. The beneficial effects of adequate Silicon may include decreased susceptibility to fungal pathogens (and insects), increased stress resistance, improved nutrient uptake and increased growth. One possible product to consider is:

Kelp (Seaweed)

In addition to being a good source of organic nitrogen and potassium, kelp contains vitamins, minerals, carbohydrates, enzymes, amino acids and growth hormones necessary for optimum plant growth. Kelp stimulates soil bacteria to release plant nutrients already found in the soil and contain cytokinins which directly affect the ability of plant roots to absorb nutrients. It is believed to increase a plant’s stem strength helping the plant handle the stress of wind, rain, drought, high temperatures, and frost.

Humic and Fulvic Acids

This is a big part of the good stuff that composting aims to develop. These complex molecules are formed as organic matter decays, and occur naturally in soils, peat, oceans and fresh waters. Humic acids are the primary extractable component of humic substances. Fulvic acids are also extracted from humic substances and may be more plant active than humic acids due to their higher oxygen content and abundance of carboxyl groups. Humic acids enhance the nutrient richness of soil and they are believed to increases the permeability of plant membranes promoting the uptake of nutrients resulting in stronger, healthier, better producing plants. For more information on applicable products visit these websites:

The field of human health supplementation is full of products and claims of increased performance and plant nutritional supplementation is not far behind. With the supplements discussed in this article and others, it may be worth a side-by-side experiment to see if the addition to ones individual soil or nutrient solution has a positive impact on plant growth and performance.

Dr. Christopher J. Kline is a Garden & Greenhouse contributing editor.

Want more information? Read these articles:

Amino Acids for Hard Water

How to Improve Garden Soil with Cover Crops

The Good and Not so Good of Synthetic and Organic Plant Food

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