Foliar feeding enables plants to absorb nutrients directly through the leaves, so it’s a particularly useful method of nutrient application. Once the plants have absorbed the nutrients through the leaves, the minerals can then be translocated by the plant within the plants tissue. Foliar feeding has been found to be quite effective in ensuring reliable nutrient uptake and healthy plant growth. This also helps protect your crops yield, and quality because the healthier the plant, the better it can resist against disease.
Nutrient uptake by plants is a very complex process
The stomata normally function to enable gas exchange for photosynthesis and releasing water vapor in transpiration. But the leaf can also work as an organ for absorption, and is effective in excreting water and substances that were dissolved in that water. There are many things about foliar fertilization that are not really understood yet, therefor it’s not an exact science, but quite helpful. One way to tell if a fertilizer has been effective is to squeeze juice from the leaves of plant and to test it with a refractometer.
If after spraying with foliar fertilizer the amount of light refracted significantly rises, then foliar application has worked. To increase effectiveness of foliar fertilizers, it’s usually recommended to use a spray enhancer to help the nutrients stick to the leaf and to penetrate the waxy sheen of most leaves. For the best results, foliar feeding should be carried out on a regular and/or weekly basis. Foliar feeding is particularly beneficial in times of high nutrient demands like during fruiting, and heavy flowering or foliage growth.
Organic gardeners sometimes use foliar feeding. Because in their effort to replenish the nutrients with organic nutrients, and keeping in line with natural and healthy, they often find themselves unable to provide trace elements to plants in sufficient quantity, especially with what’s available to them in a form that is organic. Feeding through the leaves can sometimes allow these gardeners to add some of these nutrients directly to the plant as well as the soil, for stronger healthier plants.
Applying Foliar Fertilizers
The effectiveness of foliar feeding can be a controversial subject, and has many factors. It’s just as complex as the nutrient uptake from the root system., if not more so But complexities aside, foliar fertilization is becoming more and more commonly used as a way to enhance plant nutrition, even for the home hydroponics gardener. It would be impossible to give exact foliar feeding requirements for any plant type, as well as all the complex variables, there are a few important things to consider that will affect the rate and effectiveness of the foliar fertilizers that are applied. These will have a big effect on the way the nutrients are absorbed by the leaves and then translocated within the plant.
- The finer the mist droplets the better. A real fine mist using a hydroponic fogger will give good coverage of the surface area. The foliar fertilizer solution should then be applied as a fine mist until it begins to run off the leaves, and the entire leaf surface is wetted.
- Both the top and bottoms sides of the foliage should be sprayed. Both sides of the leaves will be able to absorb the nutrients. some more than others.
- The use of a good quality, non ionic wetting or sticking agent is important for good foliar feedings. Wetting agents are important in the aiding of the adherence of the water droplets when applied by the hydroponic mister. Especially on difficult to wet leaves, as well as assisting with the absorption of the fertilizer solution into the plant leaves. It wont be able to do much good if it just slides off.
- The time of day when the solution is applied is also important. Spraying in early morning is best while it’s light, but temperatures are still cool. Also in the evening, but the conditions allow the leaves to dry off rather than stay wet for an extended length of time. That can lead to fungal infections from constant moisture on leaves.
- Foliar solutions should not be applied during hot, bright conditions. If the plants are wilting or under water stress, the plants stomata are likely to be closed as a survival instinct. Trying to conserve moisture, making the application ineffective.
- Often the greatest response to foliar feeding will occur during high active growth phases of plants like fruiting, and heavy flowering or foliage growth. During these periods of exceptional active growth, leaves are likely, and are generally most effective in absorbing nutrients.