When you’re growing plants in a hydroponic setup, you have to pay special attention to providing the necessary nutrients for your plants to thrive. Unlike plants growing outside, indoor growers cannot depend on nutrients in the soil. And unless you are using soil as a growing medium, you cannot simply mix nutrients in to be absorbed through the roots. That’s where foliar spray comes in.

What is foliar spray?

Foliar spray is simply a liquid fertilizer that is sprayed directly onto the leaves of your plants. Depending on what types of plants you are growing and what stage they are in, you may want to try different foliar sprays. Each has their own nutrient blend with various amounts of different ingredients. They are an ideal way to deliver extra nutrients to your hydroponic garden in an easy and inexpensive way.

You can purchase foliar spray in two formats—a powder that dissolves in water or a prepared liquid. Either way, the method for applying the spray to your plants is the same. You can also make your own foliar spray from compost. The decomposition of the compost generates nitrogen that is needed for healthy plant growth.

Why would you need foliar spray?

If your plants seem to be suffering from a nutrient deficiency, foliar spray is the most efficient want to boost their health quickly. That’s because plants actually absorb nutrients more quickly through the leaves than through their root and stem system. Think of it like this. The root and stems are much like your digestive system. It takes time for medicine to be absorbed fully when you ingest it. But sublingual medications (those that are placed under the tongue) are actually absorbed more quickly into your body.

Foliar spray is not typically used as a primary fertilizer but as a nutrient boost for plants already being fertilized in another way. Even if your plants are not growing in soil, you will need to supply some nutrition through the root system for the best results. Remember, foliar feeding is like giving your plants a multivitamin—even if you do it regularly, they are going to need root feeding for their main sustenance. Foliar spray is less concentrated than fertilizers that are applied to soil or growing media, so you should spray the leaves until they are dripping wet. For maximum benefit, spray both the top and underside of the leaves.

The three primary nutrients to look for in a foliar spray are nitrogen, potassium, and phosphorous. But you also want to check that the fertilizer you use provides many other trace nutrients as well to have the healthiest yields possible. A high quality foliar spray is good to keep around. You can apply it as needed when your plants appear to be growing slowly. And many plants grown for harvest provide larger, healthier harvests when misted often with a fertilizer spray. The most important time to mist is during the growth period leading up to the flowering stage of your plants.

Reach out to the Indoor Cultivator team for specific tips on the best foliar sprays and spraying schedules for the plants in your hydroponic garden.