Wednesday, July 3, 2013

Fast-acting, Foliar Feeding

Royal Standard Hosta
in bloom

Crabapple LandscapExperts point out that plants are able to absorb nutrients directly through their leaf surfaces; the epidermis and stomata. Foliar feeding is the term used for applying water-soluble liquid fertilizer directly to the leaves of a plant.

Although Foliar Feeding will never take the place of soil application of fertilizers, and in some cases, claims for the effectiveness of foliar feeding have been exaggerated, it is especially useful in cases of deficient soils or in extremes of soil pH that limit nutrient availability and uptake. Foliar feeding is also ideal for supplying the plants with trace elements, the essential nutrients that are required in very tiny amounts, as well as for a temporary or targeted spot-fix for the fast uptake of nutrients. This quick-action is the most widely agreed upon benefit, that nutrients can more quickly reach all parts of the plant than by root feeding. Noted Michigan State Horticulturist H.B. Tukey performed a landmark experiment in the 1950s using radioisotopes to trace the movement of nutrients through plants.

A classic use for foliar feeding is the application of Iron Chelate to pinpoint iron-deficieny in plants.

Fruiting plants such as tomatoes and blueberries can benefit from foliar feeding during the flowering stage, feeding when the flowers first appear and again when tiny fruits begin to form, as well as a few more times during the growing season.

  • Often, organic fertilizers such as compost tea, diluted worm compost or seaweed tea are used. Try making Compost Tea by soaking a shovel-ful of rich, homemade compost in a couple of gallons of water, then straining out the compost (and returning it to the compost pile), and using the "tea" as a foliar spray.
  • Diluted concentrations of chemical fertilizers like Rapid-gro or Miracle-Gro(R) fertilizers can also be sprayed directly on the leaves to add micronutrients and for a boost in fertility. .   
Woody ornamentals benefit
from foliar feeding

Digging Deeper
Extension Horticulturist and UW Associate Prof Dr. Linda Chalker-Scott points out that while foliar feeding does not take the place of soil applications, it is useful in several ways. 

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