In fact, many people are unaware of foliar feeding, and it is a wonderful way to ensure that plants receive extra nutrition. Rather than feeding a plant directly, it is possible to feed through its leaves. The effect is particularly pronounced in stressed plants or those deficient in a given nutrient. Let’s take a closer look to see what all the fuss is about, and see what you can do about it.
What is Foliar Feeding?
Foliar feeding can be explained by comparing it to skincare. We know that healthy skin comes from eating the right foods and drinking plenty of water. Additionally, moisturizing regularly will make it even healthier, balanced, and happier overall.
Our skin also absorbs any substance that we apply. It then travels to our bloodstream, and then on to our gut, bones, cartilage and so on. The same is true for plants as well.
It is true that plants absorb plenty of nutrients through root systems, which then pass those nutrients through the xylem and phloem. However, roots aren’t their only way to draw them in. Much like skin absorbs nutrients, plant foliage does as well.
Plants will be nourished from top to bottom and all the way through if you feed them aerial parts and roots.
How Does it Work?
It is well known that plant leaves have pores that allow them to absorb nutrients in the same way our skin does. Another way to think about it is that we dissolve our medications under our tongues instead of swallowing them.
Many medications can enter our bodies quickly rather than sinking out of our digestive tracts and then circulating throughout our bodies. These include sedatives and anxiolytics like benzodiazepines, as well as nervines, heart medications, and others.
Nitrogen, phosphorous, and potassium make up three of the most important nutrients plants need. This is why most commercial fertilizers state their N-P-K ratio on the label. These components form the building blocks for plant health and are essential for various species.
Magnesium is a critical element for plants as well. If they have yellowed badly, check the soil’s magnesium levels. You may need to supplement with Epsom salts to make sure that they receive enough magnesium.
Additional Nom Noms are Needed
All of this said, your plants need other nutrients to stay healthy, including zinc, calcium, and iron.
However, the complex part is that nitrogen, phosphorus, and potassium are best absorbed by plants by means of their roots, while iron, zinc, and calcium are best absorbed through their leaves. Since trace minerals are much lower in concentration in soil and in conventional fertilizers, they will be absorbed well through foliar feeding. By foliar feeding, you apply these nutrients to your plants’ leaves.
What Should I Use for Foliar Feeding?
It’s better to use a liquid fertilizer since you’ll be applying it as a mist or in liquid form. You can use commercial liquid fertilizer or make up a batch of your own.
In my experience, one of the best foliar feeds available is a mix of compost tea made with vermicompost (worm!) castings, water, and molasses. Fortunately, if my worms have not created enough poop to make fertilizer, then I can buy a good liquid fertilizer instead.
The liquid fertilizers are specifically designed for foliar feeding. If you can find one of these, fantastic! If not, you can dilute the fertilizer with water in a ratio of one part liquid fertilizers to ten parts water.
Similarly to diluted green smoothies, comfrey tea can help prevent nitrogen deficiency in your plants. Think of it as a diluted green smoothie-for-plants. The process is as follows: take a couple of handfuls of fresh, healthy comfrey, toss them in the blender, fill the remaining space with water, and liquefy everything.
Once you have strained out the chunky bits, dilute the mixture at the same 1:10 ratio to create an ideal foliar feeding shower.
Tools Needed for Foliar Feeding
Specifically, here’s a tip that’s unlikely to be mentioned in other blogs about foliar feeding: use a paint sprayer. No really.
Hand-held pump sprayers are nice, but can only be used when you have a small garden space to nurture. If your garden space is large, try a paint sprayer instead.
The gloves will protect your hands when hosing down large plants and areas without resulting in aching or numbness.
A mist sprayer is ideal for fine particle distribution, plus you can add a few drops of horticultural soap or oil to the spray you’re using to hydrate your plants. This will help the liquid adhere to the leaves for better absorption of nutrients.
*Note: Remember to get the undersides of the leaves too!
When and How to Feed This Way
In addition to knowing what nutrients to apply topically, it is equally critical to know when to feed your plants. For example, flowering plants should only receive nutrition while they are in their vegetative stage. Once the buds form, these nutrients actually do more harm than good.
Likewise, if you want to prevent blossom end rot on tomato or squash plants, sprinkle foliar nitrogen when the fruit is tiny. After that, water the roots daily with calcium solution.
In the early morning or in the late afternoon/early evening, spray directly into the sun before the light has completely risen, or after it’s set. Liquid droplets may act as little magnifiers.
It is vital for plant growth that the sun’s rays penetrate all those tiny droplets, but they can cause unbelievable burn damage to leaves and fruits when magnified.
How Often to Feed
It depends on the type of plant you are growing, its general health, and ideal growing conditions.
For example, when my partner and I were cultivating a garden in the hot, dry Sierra Nevada Mountains we gave the plants foliar feeds every other day. We also watered them daily at the root level and gave them root-level fertilizer every week.
Often, the plants did not have enough time to saturate themselves in all of the nutrients offered because the arid environment caused liquids to evaporate quickly.
Compared to that, the environment where I am homesteading is very different, being cool and damp. The plants that live well here, in these conditions, are very hardy, and I only apply foliar feeds when necessary if they seem to be doing poorly.
Make a note of the following factors:
- General daily temperatures
- Arid or damp conditions
- Species being grown
- Whether foliar issues need to be addressed (such as deficiencies or insect damage)
- Then gauge your feeding cycle accordingly.
In hot and dry climates, apply foliar feeding every four days or so if your plants are susceptible to wilting. In cool and moist climates, you may only need to apply foliar feeding if your plants come to peak.
Potential Problems
It has been mentioned that some people make the mistake of feeding once blossoms are open. This can result in flower buds getting damp inside, and they may rot or fall off instead of turning into fruit. That will undo all the hard work; it’s not even something I enjoy thinking about.
It’s common for people to get overly excited about hosing down their plants. Aim for a light misting and stop once you notice the liquid particles start to edge together and dribble. It shouldn’t be so heavy that the plants’ roots are submerged.
You don’t want to drown them with water, which can create the types of soil-borne pathogens that thrive. This method should be compared to drying out your own skin slowly and gently; aim for a healthy glow instead of slathering with a trowel.
If you’re offering too much nutrients to your plants, you may also overwhelm them with too much good stuff.
In the case of fertilized fruit trees, nitrogen-rich liquid fertilizer may cause your plants to focus all their energy on growing foliage instead of fruit. If you have nice, lush tomato plants, but only produce a few edible ones, then you’re doing your plants no good.
Trying to fertilize spinach, chard, or kale with phosphorus-rich fertilizer will also not do much good.
If you’re feeding several species, determine what they need the most, and feed them accordingly.