Why the foliar fertilization if the plants are predisposed to feed naturally through the roots? Because a part of water and mineral salts can also be absorbed through the leaves, in lower quantities but more quickly and effectively than root absorption.
There foliar fertilization in short, it is suitable for emergency therapies in the event of a lack of one or more elements, more than for ordinary plant nutrition. To feed the plants regularly, when they are healthy, it is preferable to use traditional fertilization which fattens and renews the soil, preventing it from drying up, turning into a mere support.
Watch out for phosphorus!
With the foliar fertilization both the main elements and the microelements can be administered to the plants. Except for one, phosphorus, which together with nitrogen and potassium is one of the main elements for plant nutrition. No plant can absorb phosphorus through the leaves, therefore a true foliar fertilizer should not contain it as it would be useless.
Many liquid fertilizers are suitable for both types of fertilization, root and foliar, but if you already have a product with high amounts of phosphorus at home, know that it is not suitable for foliar fertilization.
Specific products for the foliar fertilization they usually contain iron, zinc, copper, boron… that is, those microelements which plants can suffer from temporary deficiencies and which are better if they are absorbed quickly. Or they are products that provide stimulating and strengthening substances, also these to be rapidly absorbed.
The most frequent case in which the foliar fertilization it is that of ferric chlorosis, that is the lack of iron that leads to yellowing of the leaves. Iron can also be administered by roots, but the action is faster and more effective through the leaves.
Liquid supplement based on iron
Organic foliar reinforcer
When and how
There foliar fertilization it is more effective on young leaves, which have a better absorption capacity. The absorbency improves when the leaves are slightly wet, but not dripping. Before any intervention, a good irrigation of the soil is also useful.
The foliar fertilizer however, it should not be sprayed during the hottest hours of the day or under the sun's rays. The best time to make the foliar fertilization it is late afternoon, preferably on an overcast and not too hot day. If it is a generic fertilization, the most favorable period coincides with the vegetative restart. The single elements, iron etc ..., can always be administered when necessary.
Sprayer pump for foliar fertilization