All plants require a range of different minerals for healthy growth. Usually, a plant absorbs the minerals it needs from the soil in which it is growing. However, with hydroponics you need to provide your plants with the minerals they require in the form of a nutrient solution. This allows you tight control over the minerals your plants receive.
Nutrients contain essential elements that are vital for plant growth. If these essential elements, as well as carbon dioxide (CO²) and light, are made available to a plant, they can produce the compounds (food) the plant needs for normal growth. The most important elements are known as the ‘macro elements’. These consist of:
- Nitrogen (N) - A plant uses Nitrogen for rapid growth and the development of foliage, leaves, flowers/fruit and seeds.
- Phosphorus (P) - Phosphorus plays a major role in transporting glucose (plant food), stimulating root development, and promoting flower/fruit and seed production.
- Potassium (K) - Like Phosphorus, Potassium promotes flower/fruit and seed production. It also helps to protect a plant from disease.
All plants require large quantities of the macro elements. During the vegetative cycle your plants will benefit from extra nitrogen, while more phosphorus and potassium is beneficial in the flowering stage. Different nutrients are used to ensure that your plants receive all the minerals they need in the right proportions at the correct stage of their lifecycle. There are two types of nutrient solutions available:
A ‘Grow’ mix contains high levels of nitrogen; you should, therefore, use this nutrient solution during your plant’s vegetative cycle.
A ‘bloom’ mix contains high levels of potassium and phosphorus, so change to this solution when your plants start flowering.
Plants also require other elements known as ‘secondary macro elements’ and ‘micro elements’.
Secondary macro elements are magnesium, calcium and sulphur. Micro elements (also known as ‘micronutrients’) are manganese, boron, copper, zinc and molybdenum. The table at the end of this document highlights why a plant needs each of these minerals.
Nutrient solutions are available in one, two and three-part packs. They are normally in concentrate form:
One-part nutrient solutions
One-part nutrient solutions are very easy to use and popular with beginners or growers who prefer the simpler method of feeding. The one-part removes the chance of incorrectly measuring the components of the two-part and three-part.
Two-part nutrient solutions
Two-part nutrient solutions consist of two bottles which are added (in equal amounts) to water in order to supply a full spectrum of elements to your plants. As the nutrients are more concentrated and specific, you can achieve very accurate feed levels for your plants at all stages of their life cycle. This helps to improve plant growth and health. Two-part feeds are the most popular nutrients as they are easy to use whilst delivering good nutrient levels.
Three-part nutrient solutions
Three-part nutrient solutions require three bottles to complete the nutrient formulation and are generally more suited to the professional grower. A three-part solution enables you to provide your plants with the most precise nutrient management throughout their life cycle– even more so than a two-part. It allows maximum control over the nutrient delivered to your plants. Due to its more complex nature, three-parts are not suitable for beginners.
Maintaining the nutrient solution
Maintaining the nutrient solution involves keeping adequate nutrient strength, pH levels and optimum temperatures.
The strength of nutrient is the amount of dissolved salts that a nutrient contains. Nutrient strength plays an important role in maintaining the health of a plant. If the nutrient is too strong, the leaves of the plant can become leathery, curl downwards or even burn at the tips. If the nutrient strength is too low, then the plant will turn yellow, stretch and become susceptible to disease. The strength of a nutrient solution is known as the ‘Parts per Million’ (PPM) or ‘electrical conductivity’ (EC). These can be measured with a PPM/EC meter, which allows you to maintain the required level for the stage of your plants life cycle.
The pH is the measure of the acidity or alkalinity of a nutrient solution. A pH value of 0 to 6.9 indicates the nutrient solution is acidic, 7.1 to 14.0 alkaline. While a reading of 7 shows the nutrient solution is neutral. Ideally, the pH level should range between 5.5 and 6.5. If you allow the pH level to fall outside of this scope, it will affect your plant’s ability to absorb nutrients. This results in poor yields and slow growth rates.
A good temperature around the roots can encourage root growth and nutrient uptake. Never let the temperature of your nutrient solution drop below 60°F, as cold water will limit the ability of roots to absorb water and minerals, and drastically reduce yields. Similarly, a temperature too high – above 85°F – will starve your plants of the oxygen they need for healthy growth. Ideally, you should aim for a temperature of approximately 70°F.
Additives are extra supplements that can be added to nutrient solutions to help the plant use nutrients more effectively.
This can promote growth and improve the general health of your plants. Additives can also encourage specific processes, such as rooting and flowering. Although they’re not essential, additives can be very beneficial in achieving the most from your plants.
Maintaining all of the factors discussed in this article should help your plants to grow strong and healthy. If you require any more information, please don’t hesitate to contact us.
Please see below for a list of essential elements a plant requires:
|Symbol||Type||Symptoms of deficiency|
|Nitrogen||N||Macronutrient||Stunted growth and/or yellow leaves. Purpling along the veins on the underside of larger leaves.|
|Phosphorus||P||Macronutrient||Growth stunted, very dark green plant, leaves develop grey to purple dead patches.|
|K||Macronutrient||Slow growth and /or yellow to brown margins on older leaves|
|Mg||Secondary||Older leaves yellow; as the deficiency progresses, small brown patches develop in the yellow areas.|
|Ca||Secondary||Yellow/brown spots appear on the edge of leaves. These spots can also be surrounded by a sharp brown outlined edge. This often affects the older leaves first.|
|S||Secondary||Small growth, all leaves turn yellow, reddening of the veins on the underside of leaves.|
|Fe||Micronutrient||Uniform yellowing of young leaves, while the veins remain green. Eventually, the whole leaf becomes bleached.|
|Mn||Micronutrient||Yellowing between veins on young leaves, with brown patches forming along the veins.|
Younger leaves show a light yellowing/browning. A cluster of leaves develop in the same place. Leaf margins twist and leaves become brittle.
|Cu||Micronutrient||Young leaves drooping, a wilted appearance, yellow to brown patches. Mature leaves may become bleached between the veins.|
|Zn||Micronutrient||Older leaves develop brown patches in between the veins. Young leaves very small and/develop in a cluster in the same space.|
|Mo||Micronutrient||Upward cupping of the leaves with mottling. Looks like nitrogen deficiency without the reddening on underside of the leaves.|