Understanding how leaves function is essential to becoming a skilled plant parent and garden steward. To keep your plants thriving year-round, it’s important to nurture them through the various challenges they face. In this guide, we’ll explore foliar feeding, stomata, and leaf cuticles—key elements that will support your plants’ health and longevity.
photo credit Science Photo Library
The term "foliar" comes from the Latin word folium, meaning "leaf." In the plant world, providing nutrients through the leaves is known as "foliar feeding." This method helps address nutrient deficiencies, promotes plant growth, and doubles as a way to clean leaves while preventing and treating pests. There's like spraying your plants and being rewarded with that radiant, healthy shine for a plant parent!
While the vast majority of nutrients (80-90%) of plants, needed to thrive and grow, are taken up through the roots, foliar feeding is an effective method of treating nutrient deficiencies while boosting plant growth, especially during times of stress (pest infestations, disease, moving, etc.).
How does it work?
Foliar feeding occurs throughout the leaf cuticle where the stomata (aka stoma and stomate) are located. Stomata are tiny openings (pores) composed of living cells on the epidermis of leaves, just like the pores on our own skin! These pores look like tiny mouths opening and closing to allow for gas exchange and micronutrients.
Generally located on the bottom side of the leaf and on some plants, stomata also appear along the stems of some plants. Being located on the underside of the leaves protects them from extreme heat (sun) or from extreme airflow (wind). These pores are surrounded by guard cells which contain chloroplasts that are responsible for photosynthesis, the life giving energy of the plant– a vital function. The guard cells are also responsible for opening and closing the stomata, an important role for regulating hydration and gas exchange.
photo credit Science Photo Library
Foliar Feeding vs. Fertilization
To be clear, foliar feeding does not replace fertilization through the soil by any means, however it can supplement nourishment to your plant. Stoma are able to absorb dissolved micronutrients and minerals that can be translocated throughout the plant where extra nutrition is most needed. Many farmers apply a dose of fertilizier by foliar feeding to boost crop yield and overall plant health, especially to heavy feeders like tomatoes and melons.
The leaf cuticle is the outermost layer of a leaf. This layer contains a pathway of micro pores. It's important to note that all plants are not receptive to foliar feeding the same way. Each species has a varying number of stoma on their leaf cuticle and a unique thickness to their leaf cuticle and therefore foliar feeding efficacy varies from plant to plant.
The Double Whammy
When it comes to plant care, we don’t take shortcuts. Plants deserve more than just a healthy glow and pest protection—they deserve molecular health from the inside out. That’s where our plant care duo comes in to address plant health from all angles, helping you keep your plants thriving while avoiding toxins and harmful chemicals.
When showering your plants and cleaning their leaves and stems, you can use either of our tonics. Sacred Soil Tonic (formulated for soil applications) also serves as a foliar feed for all plants, including those with epicuticular waxes like staghorn ferns and air plants. Sacred Leaf Tonic not only nourishes your plants but also treats pests like thrips, aphids, scale, mealybugs, and spider mites naturally and effectively. Be sure to check out our blog posts covering pest care.
Sending love and warm wishes for a healthy new year of growth. 🌱
Karina and Team SE