Foliar feeding is a cultivation technique that takes advantage of a plant's ability to absorb nutrients through its leaves. This technique offers a simple way to maximise yields, speed growth, and help your plants recover from disease or weakness.

 Foliar Feeding

What is foliar feeding exactly?

Plants generally absorb nutrients through their roots, which is then transported to various areas on the plant where it is can be used to create energy, or is used to create the plants structure like leaves or stems. 

Foliar feeding on the other hand, takes advantage of the ability for leaves to absorb nutrients and water through small pores on the leaf surface. This allows the nutrients to reach the leaves quickly and effectively. Delivering the nutrients exactly where it needs to go quickly and effectively.

Some plants, such as Tillandsia (otherwise known as air plants), do not have functional roots, and instead obtain all of their nutrition this way. They are specialists in absorbing nutrients through their leaves, but are definitely not the only plants that can do this. Many herbs and trees can also do this. In fact they thrive from it.

Foliar feeding is as easy as mixing a nutrient solution with water and misting it all over the plants leaves. You can purchase special blends designed for foliar feeding, or mix your own using a nutrient formula of your choice. Just be sure to dilute these nutrients to about 10% of the recommended dosage and use filtered water. Organic fertilizers can also be used and make great foliar feeds.

The benefits of Foliar Feeding

Foliar feeding, although generally not the main source of nutrition for a plant. Has some marked benefits on the health of a plant.

1. Helps weak or damaged plants recover

Foliar feeding is highly beneficial for weak or sick plants, such as after the invasion of a pest or disease. When a large portion of the plants roots have been damaged by the pest, it can be hard to maintain the energy requirements of the plants leaves and foliage. These plant structures have a high demand for nutrition and water which the roots may no longer be able to keep up with until after they have had a chance to grow and recover.

Foliar feeding can be a great benefit to these plants because it allows you to deliver the nutrients directly to the leaves. This helps to buy the plant time and gives it the opportunity to grow new roots to sustain its growth on its own again.

Even in plants that have not been damaged that badly, foliar feeding can help to ease the plant back into proper health once again.

2. Speeds growth

For many growers, achieving optimal growth and yield are of the utmost importance. Foliar feeding can make that extra level of optimization for achieving the best results possible from your plants. It allows your plants to absorb the maximum amount of nutrition possible, even if the regular feeding cycle has been maxed out. This simple technique can have profound implications on both the speed of growth and the yield.

3. It has some mild insecticidal activity as well

This is especially true with synthetic foliar feeds which may deliver the mineral salts directly onto the leaf surface. Some organic fertilizers like bat guano or kelp can directly inhibit spider mites ability to thrive as well. This is only an added bonus however and should not be relied on for large spider mite infestations.

Tips For Foliar Feeding

1. Don’t Over do it

Make sure to follow the directions on the label of your foliar feed. Overdoing it can burn the leaves in the same way that adding too much fertilizer to the water can damage the roots. These fertilizers usually come in the form of a mineral salt, which can build up over time, and if in too high of a concentration can actually destroy the cells of your plants rather than nourish them. Just as with all things, it's possible to have too much of a good thing.

2. Keep the air circulation moving

Adding nutrition to your plant's leaves can provide them with a good source of food to drive growth. Unfortunately this means an added level of nutrition for bacteria and fungi as well. Minimize the risk of this occurring by ensuring the air is continually moving within your grow room. When the air becomes stagnant, it is all too easy for organisms like fungi and bacteria to thrive and grow.

3. Mist, not soak

You want to mist your plants, and apply an even coat of foliar feed to the leaves, but you don't want to completely drown your leaves. This will only promote bacteria and mold growth and can actually damage the leaves on your plants.

4. Be careful with lighting

The fertilizer salts contained in foliar feeds, have a tendency of amplifying the light energy from the sun or your grow lamps. If these lights are beaming down high intensity light energy on your freshly foliar fed plants, it can actually cause sun burns on your plants leaves. Avoid this by moving your lights further away from the surface of the leaves for a few hours after foliar feeding, or turn them off completely.

5. Limit to once or twice a week

As mentioned earlier, it is possible to have too much of a good thing. Foliar feeds contain dissolved mineral salts, which can build up on the leaves and cause damage to the leaf surface. This is avoided easily by giving the plants plenty of time to absorb these nutrients. After about a week's time, there will be only trace amounts of these nutrients left on the leaves if any at all, thus avoiding the buildup of these chemicals.