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Any of these factors, if neglected, could become the weak link in the chain.
Read the article Creating Your Own Grow Room for information on these subjects.
These are the most common problems people encounter growing hydroponically:
Yellowing bottom leaves/older growth
The Nitrogen story:
Nitrogen is a transferable element (this means the
plant can move it around as needed). If a plant is not receiving enough
Nitrogen from the
roots then it will rob Nitrogen from the older growth. In Hydroponics,
usually the pH is too high and has locked out the available Nitrogen.
Always check the pH before increasing nutrient level.
Save the plant: Leach! Check the pH, and adjust if
necessary to 5.8 - 6.3. Check and maintain nutrient level. You may foliar
feed (spray)
with a pinch of CaNO3 (Calcium Nitrate) in a Liter of pH balanced water
for quick results.
Leaf tips curl up
This is usually a Magnesium deficiency caused by a too low pH level.
Save the plant: Leach, check and adjust the pH level.
You also may foliar feed (spray) with a pinch of MgSO4 (Magnesium Sulphate - #5 of our Six Pack)
in a Liter of
pH balanced water for quick results.
Rapid Defoliation (lower leaves on the plant yellow and fall)
Under or Over Watering
Over Watering
Plants are stunted and wilt or droop. As the problem gets more severe, the foliage becomes spotted as roots become brown and mushy. Gray fuzzy mould accumulates on the flowers, stem and leaves. Roots are brown and mushy.
Save the plant: You may need to increase oxygenation and/or lower the amount of times you flood depending on which growing system you are using.
Under Watering
Plants are stunted and wilt or droop. Leaves become dry and brittle.
Save the plant: Leach plants. Increase amount of water or how often you water depending on which growing system you are using.
Gradual Defoliation (lower leaves on the plant yellow and fall)
1. Rapid changes in room temperature
Save the plant: Invest in a minimum maximum thermometer to keep track of temperature fluctuations in your grow room. Raise or lower the temperature depending on which is occuring. Ideal temperatures for the grow room are 18 to 25 degrees Celsius during the light cycle and 12 to 18 degrees Celsius during the night cycle.
2. Insufficient light
New foliage is pale, stunted and spindly.
Save the plant: Add more light.
3. Nutrient Deficiency
Plant looks unhealthy and pale. Leaves and/or stems show signs of yellowing, purpling, reddening or browning depending on which specific nutrient deficiency.
Save the plant: Consult the chart below to diagnose which deficiency you may have. Then click here for a remedy.
| Plant Nutrient |
Type |
Visual symptoms |
| Nitrogen |
Deficiency |
Light green to yellow appearance of leaves, especially older leaves; stunted growth; poor fruit development. |
| Excess |
Dark green foliage which may be susceptible to lodging, drought, disease and insect invasion. Fruit and seed crops may fail to yield. |
| Phosphorus |
Deficiency |
Leaves may develop purple coloration; stunted plant growth and delay in plant development. |
| Excess |
Excess phosphorus may cause micronutrient deficiencies, especially iron or zinc. |
| Potassium |
Deficiency |
Older leaves turn yellow initially around margins and die; irregular fruit development. |
| Excess |
Excess potassium may cause deficiencies in magnesium and possibly calcium. |
| Calcium |
Deficiency |
Reduced growth or death of growing tips; blossom-end rot of tomato; poor fruit development and appearance. |
| Excess |
Excess calcium may cause deficiency in either magnesium or potassium |
| Magnesium |
Deficiency |
Initial yellowing of older leaves between leaf veins spreading to younger leaves; poor fruit development and production. |
| Excess |
High concentration tolerated in plant; however, imbalance with calcium and potassium may reduce growth. |
| Sulfur |
Deficiency |
Initial yellowing of young leaves spreading to whole plant; similar symptoms to nitrogen deficiency but occurs on new growth. |
| Excess |
Excess of sulfur may cause premature dropping of leaves. |
| Iron |
Deficiency |
Initial distinct yellow or white areas between veins of young leaves leading to spots of dead leaf tissue. |
| Excess |
Possible bronzing of leaves with tiny brown spots. |
| Manganese |
Deficiency |
Interveinal yellowing or mottling of young leaves. |
| Excess |
Older leaves have brown spots surrounded by a chlorotic circle or zone. |
| Zinc |
Deficiency |
Interveinal yellowing on young leaves; reduced leaf size. |
| Excess |
Excess zinc may cause iron deficiency in some plants. |
| Boron |
Deficiency |
Death of growing points and deformation of leaves with areas of discoloration. |
| Excess |
Leaf tips become yellow followed by necrosis. Leaves get a scorched appearance and later fall off. |
1. Adapted from: W.F. Bennett (editor), 1993. Nutrient Deficiencies & Toxicities in Crop Plants, APS Press, St. Paul, Minnesota.
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Information provided by: http://www.uog.edu
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Leaves of plants are burnt and dry
Nutrient Toxicity
Leaf tips curl under / leaf tip burn
(browning). Consult the chart above to diagnose which toxicity you may have.
Save the plant:The Nutrient level is too high. Leach and decrease the nutrient level. You can also use DNF Clear as a flush. Check the pH, and adjust if
necessary to 5.8 - 6.3.
Small, light flecks, giving the plant a somewhat speckled appearance and webbing
Spider Mite Infestation: Spider mites are common pest problems on many plants around yards and gardens. Injury is caused as they feed, bruising the cells with their small, whiplike mouthparts.
Following severe infestations, leaves become discolored, producing a gray or bronze look to the plant. Leaves and needles may ultimately become scorched and drop prematurely. Spider mites frequently kill plants or cause serious stress to them.
Save the plant: Introduce a Spider Mite Predator such as Phytoseiulus persimilis New Zealand Strain.These are bright orange mites (0.5 mm./1/20 in.), and larger than two-spotted mites. Persimilis breeds twice as fast as the spider mites to provide a fast knock down. These mites do not form webs, but use webbing to move along the plant to capture the spider mites. Optimum Conditions, 22-35C (72-100F), 60-80% humidity. There are also Natural Sprays available. Enhance should be used on a regular basis to keep plants healthy and pest resistant.
Leaching
Leaching should be done at every reservoir change and before countering
any problem. This will rid the medium and root zone of toxic salt build
up.
To leach, rinse the root zone with straight pH balanced water.
Use twice as much liquid as
the hydroponic container would have held when empty.
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