Monthly Archives: May 2018

  • Grow the best Hydroponic Broccoli

    Broccoli is a nutritious winter vegetable and very well suited to grow in hydroponics. It can be started from seeds or plants.

    Media bed method is recommended because Broccoli grows into a large and heavy plant by harvest. Growing broccoli is moderately difficult because it is high nutrient demanding plant and also susceptible to warm temperature.








    Growing Conditions: -

    Broccoli grows best when the daytime temperature is at 14-17 °C. For head formation, winter varieties require a temperature of 10-15 °C. Hot temperatures cause premature bolting.

    Growing Instructions: -

    Transplant the seedlings into media beds once it has 4-5 true leaves. And seedlings should be positioned 450 cm apart as closer spacing will produce smaller central heads. Broccoli, like cabbage, is susceptible to cabbage worms and other persistent pests.

    Pests/Diseases: -

    • Aphids: Curling leaves may mean that the plant's sap is being sucked by insects. Apply soapy water to all sides of leaves whenever you see aphids.
    • Downy mildew: Yellow patches on leaves are usually caused by moist weather. Keep leaves as dry as possible with good air circulation. Buy resistant varieties.
    • Cabbage loopers: Small holes on the leaves between the veins might be because of green caterpillars. Look at the undersides of the leaves. Hand pick if the problem is small or control with Bacillus thuringiensis, a natural, bacterial pesticide.
    • Cabbageworms and other worm pests: Treat same as loopers.
    • Cabbage Root Maggots
    • Whiteflies
    • Nitrogen deficiency: If the bottom leaves turn yellow and the problem continues toward the top of the plant, the plants need a high nitrogen (but low phosphorus) fertilizer or blood meal. Blood meal is a quick nitrogen fix for yellowing leaves.
    • Clubroot: Quickly wilting plants may be due to this fungus. The entire plant, including all roots and root tendrils, must be gently dug up and removed. If the roots are gnarled and misshapen, then clubroot is the problem. Act quickly to remove the plants so that the fungus doesn't continue to live.

    Harvesting: -

    • In terms of timing: Harvest broccoli when the buds of the head are firm and tight before the heads flower. If you do see yellow petals, harvest immediately.
    • For best taste, harvest in the morning.
    • Cut heads from the plant, taking at least 6 inches of stem.
    • Cut the stalk of the main head at a slant, about 5 to 8 inches below the head.
    • Most varieties have side-shoots that will continue to develop after the main head is harvested. You can harvest from one plant for many weeks, in some cases, from winter to beginning of summer, if your summer isn’t too hot.
    • Store broccoli in the refrigerator for up to 5 days. If you wash before storing, make sure to dry it thoroughly.
    • Broccoli can be blanched and frozen for up to one year.

    Parameters for good yields: -

    PH: 6-7

    PPM: 1960-2450

    EC: 2.8-3.5

    Plant Spacing: 40-70 cm (3-5 plants/sqm)

    Germination time and temperature: 4-6 days with a temperature of 25°C

    Growth time: 60-100 days from transplant

    Average daily temperature: 13-18°C

    Light exposure: full sun; can tolerate partial shade but will mature slowly.

    Recommended method: Media bed

  • Understanding PH Control

    What is pH?

    pH is a measure of the relative concentration of hydrogen ions (H+) to hydroxide ions (OH-). The greater the number of H+ ions in relation to OH- the more acidic the solution becomes. The greater the ratio of OH- ions to H+, the more basic the solution becomes. PH is measured on a scale of 1-14. A reading below 7 means that there are more H+ ions and a reading above 7 indicates more OH- ions. At pH 7 there are the same number of H+ ions as OH- ions so the pH is neutral, neither acid nor base.










    Acids and Bases

    Any substance that increases the concentration of hydrogen ions (lowers the pH) when added to water is called an acid. A substance that reduces the concentration of hydrogen ions (raises the pH) when added to water is called a base or an alkali. Some substances enable solutions to resist pH changes when an acid or base is added. These substances are called buffers. Buffers are very important in helping to maintain a relatively constant pH in a feeding solution and in the root zone after the water has been applied to the crop. Most greenhouse water supplies have sufficient alkalinity that they require routine acid addition to correct the pH to the normal 5.8-6.2 feeding range. At this level, the irrigation water tends to have a neutral effect on media pH, although this depends on the buffering capacity of the media. Some growers use very pure water from rain and surface sources. In these situations, they may need to apply a combination of acid and base materials to stabilize and buffer the pH.

    Why does pH Matter?

    Improper management of media pH can result in poor growth and reduced plant quality in greenhouses and nurseries. The pH or soil reaction has a primary influence on the solubility and availability of plant nutrients. Many crops have a narrow range of pH tolerance. If the pH of the soil medium falls above or below this tolerance zone, they may not grow properly due to nutrient deficiency or toxicity.

    The availability of most fertilizer elements is affected to some extent by the media pH. Calcium and magnesium become more available as the pH increases, while iron, manganese, and phosphorus become less available. A one-unit pH drop can increase the solubility of manganese by as much as 100 times, and the solubility of iron by as much as 1000 times.

    Why Adjust Irrigation pH?

    By carefully modifying the pH and alkalinity of your irrigation and feed solutions, you can help maintain the desired plant growth and quality. There are other reasons to monitor and control pH in your irrigation water and nutrient solutions: 1) Solution pH affects the availability of nutrients. 2) Correct pH helps ensure dissolved fertilizer concentrates remain in solution when mixed in the water supply. 3) Acid injection can be used to neutralize excess alkalinity in water supplies.

    Understanding The pH Scale

    The pH scale measures the relative concentration of Hydrogen Ions (H+) and Hydroxyl ions (OH-) in a solution. Technically, the pH of a solution is defined as a negative logarithm of the hydrogen ion concentration. The "P" is the mathematical symbol for a negative logarithm and the "H" is the symbol for hydrogen. The pH scale measures this, and places a value on it ranging from 0 to 14. Since it is a log scale, each number on the scale is 10 times greater (or smaller) than the next. A lower pH number corresponds to a higher concentration of hydrogen ions (H+) relative to hydroxyl ions (OH-). A higher pH number corresponds to a relatively lower concentration of hydrogen ions

    Measuring pH

    There are several methods available for measuring pH, but the most useful and practical is an accurate pH meter. Follow the instructions included to preserve the accuracy and life of your instrument. These meters typically use a liquid filled glass probe, although some are now using flat sensor technology.

    Water and nutrient solution samples can be measured directly or preferably after a few hours of settling time. Dissolved CO2 in water supplies can cause slightly lower readings until the sample has come to equilibrium with the air. When testing media, freshly mixed samples of media should be watered and allowed to stand for 24 hours before a reading is taken to release some of the lime and fertilizers. The preferred method for testing media pH is to obtain several representative samples of a crop and to measure each separately. Multiple measurements give greater accuracy in reading, and shows the degree of variability of pH across several locations. A saturated media extract or a 1:1 soil to distilled water ratio is fine for measuring media pH.

    Factors Affecting pH

    These variables can affect the final pH, the rate of pH change, and the amount of modifying action required. They include the effects of:

    • Soil temperature
    • Fertilizer materials (may raise, lower or buffer pH)
    • Soil amendments such as gypsum, sulfur and lime
    • Root volume & metabolic activity
    • Soil microorganisms
    • pH and alkalinity of the irrigation water
    • Leaching fraction
    • Buffering capacity of both the soil medium and the irrigation source
    • Media cation exchange capacity
  • Know your water

    Know your water to know your best water soluble fertilizer options.

    Water quality is the single most important factor in determining solubility and nutrient availability for plants. It's especially important that you test for the key parameters like pH, TDS and EC if you have one of the following factors:

    •  Borewell water
    • Change in irrigation water source
    •  Multiple sources of irrigation water
    •  Recent flooding or droughts

    The primary considerations when formulating and evaluating your plant nutrition program are:

    1. Nutritional content of the water
    2. Its effect on growing media pH
    3. Its content of potentially toxic components

    With today's soilless growing media, water's alkalinity is the main area of focus. Alkalinity is a measure of how much buffering the water will provide to the given growing media.
    If alkalinity is too low, the growing media pH can plunge due to acidic influences like fertilizer, growing media components and plant root exudates. If this happens micronutrient toxicities can occur. Conversely, if alkalinity is too high, growing media pH can soar, leading to deficiencies in micronutrients, such as iron. In this case, you may be applying plenty of iron, but it becomes unavailable to the plant at higher growing media pH.
    A thorough water analysis will measure the alkalinity of your irrigation water as well as many other elements. Having your water tested can make the difference between growing a good crop and growing a great crop!

    The four main water types:

    While it's important to get complete water analysis of your irrigation supply, you can base your fertilizer choices on your water type category and the plants you're growing.

  • Calcium - An essential plant nutrient

    With all of the emphasis on N-P-K in agriculture, calcium and magnesium are sometimes overlooked. Calcium and magnesium are essential macro-elements, used in relatively large quantities. In fact, plants take up more calcium than phosphorus!


    • Calcium is much needed in plant growth for below reasons:
    • Participates in metabolic processes of other nutrients uptake.
    • Promotes proper plant cell elongation.
    • Calcium is required for the stability and function of cell membranes and acts as a type of `cementing agent ' in the cell walls in the form of `calcium pectate'.
    • Participates in enzymatic and hormonal processes.
    • Helps in protecting the plant against heat stress - calcium improves stomata function and participates in the induction of heat shock proteins.
    • Helps in protecting the plant against diseases - numerous fungi and bacteria secret enzymes which impair plant cell wall. Stronger Cell walls, induced by calcium, can avoid the invasion.
    • Affects fruit quality.
    • Has a role in the regulation of the stomata.


    In hydroponic systems, adequate levels of calcium are usually maintained with calcium nitrate or other calcium salts. Therefore the lowering of calcium levels in the plant tissue and the occurrence of deficiency symptoms usually result from the influence of other factors which impede either calcium uptake or its distribution within the plant. Calcium uptake may be reduced by the competitive effects of a high concentration of other cations such a potassium, sodium, magnesium or ammonium in the solution. And since calcium moves in the xylem tissue, its uptake is also affected by low root temperature and by restricted water movement through the plant caused by high salinity in the media or excessive humidity in the atmosphere.

    Higher EC levels in the nutrient solution reduce the uptake of calcium, unlike nitrogen and potassium which increase in concentration in leaf tissue with higher EC levels. Reducing the EC of the nutrient enhances water uptake and with this, more calcium can be taken up and transported within the plant to developing tissue.


    • Calcium deficiency results in marginal yellowing, tiny and deformed leaflets, curled up margins in Tomatoes.
    • White spots form on edges and veins of upper leaves in Cucumbers.
    • Growing point region of youngest leaves remains small, later the leaves shrivel and growing point dies.
    • Blossom end rot is observed in tomatoes while Cucumber buds might abort and finally, plant dies back from the apex.


    The simplest means of preventing calcium deficiency disorders such as tipburn and blossom end rot is to maintain adequate calcium levels in a balanced nutritional solution with the correct EC level. Use 0.75% - 1.0% calcium nitrate solution as foliar spray in acute cases. As always, moderation is always recommended when using additives. Start with very low dosages, see how the plants respond and add more if necessary. Keeping the plants stress free, providing gentle air movement across the leaf source to encourage transpiration and preventing excessive temperatures all help drive calcium into leaf tips and developing fruits.

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