When top-up supplements are needed, a deficiency has been spotted or the root system is underperforming, a fast and effective way to get nutrients into the plant is as a foliar feed. With foliar applications, nutrients enter through the stomata or the cuticle and can get to work straight away. But, as basic plant biology reminds us, the opening and closing of stomata are affected by environmental conditions, hence it is best to make foliar applications during periods of high humidity and not when sunlight levels and temperature are high.
The nature of the leaf surface will affect penetration through the cuticle, with waxy upper surfaces making it difficult for the feed to pass through. Research shows that adjuvants can be used to help spread the fertiliser across the leaf, giving it a better chance of being absorbed than if it were in droplets. Increasing drying time can also help to boost penetration rates. New products introduced this year include Tip Top Turbo and PHC Organic from Solufeed as well as HortiKelp and HortiBoost from Hortifeeds.
Note: The following table includes many of the products suitable for foliar application. Omission of any company or product does not imply criticism
DOWNLOAD - table of liquid fertiliser products for foliar application