I recently heard about spraying fertilizers on leaves. I was wondering what kind vegetables and plants need fertilizer to be sprayed on their leaves? How often should fertilizer be applied to leaves? Can leaves absorb the nutrients like roots?
Thank you for your help.
Foliar fertilizers are sprayed as liquids directly onto the leaves of a plant, They are absorbed through the leaves, which contain tiny pores on their surfaces. These fertilizers are sometimes used to supplement plants’ nutrient needs, but are not a substitute for traditional fertilizers that are applied to the soil.
Roots are much superior to leaves in absorbing large amounts of nutrients. Major nutrients needed by plants (called macronutrients) are nitrogen, phosphorus and potassium, and fertilizers containing these nutrients should be applied to the soil, for best absorption.
However, foliar fertilization is useful in certain situations, like where a plant is deficient in micronutrients. For example, if soil has a high pH (i.e., is alkaline), sufficient iron may not be available for absorption by plant roots. The long-term solution for this issue is to lower soil pH, but a temporary fix might be to apply iron salts directly to the plant leaves – which can absorb this micronutrient. Foliar fertilizers can also be used when young plants are being transplanted into soils that are too cold for plants to absorb nutrients from that soil.
Some issues to consider: Foliar fertilizers are usually less concentrated than traditional ones, as higher concentrations can damage leaves or even kill the plant. Leaves may have waxy coatings that will decrease or prevent the absorption of water and other substances (including foliar fertilizers) by the plant. And there is often a lot of runoff following leaf spray, with the foliar fertilizer ending up on the soil, to be absorbed in the usual way – by the plant roots. If it rains soon after application of foliar spray, as most of the spray may be washed off the leaves, another application may be necessary.
There are no particular plants that “need” foliar fertilizers – deciding to use them would depend on several factors. If you do decide your plants would benefit from application of a foliar fertilizer, check with your local nursery to make sure that this would help your plant and also to review directions for dilution and application of the product.
Note that foliar fertilizers are not the same as traditional liquid fertilizers, which are applied to the soil.
I’d suggest that you consider which fertilizer to use based on the types of vegetables and other plants you will be growing. For example, tomatoes are heavy feeders and need regular fertilizer. Other plants may just require good, rich soil — by adding organic matter like manure and compost to your garden soil every year, you can improve both soil structure and the level of nutrients in the soil, decreasing the need for fertilizers.
June 3 2021