FOLIAR fertilization

Foliar application of fertilizers provides a way of supplying nutrients directly to plants. All plants absorb nutrients to a limited extent through their leaves and stems, using stomata – little openings similar to the pores of our skin.

Plants absorb foliar fertilizers far more rapidly than soil-applied ones, up to 20 times faster, prompting a quick reaction in the plants.

The purpose of foliar feeding is not to replace soil fertilization. Supplying a plant’s major nutrient needs (nitrogen, phosphorus, potassium) is still most effective and economical via soil application (see adding soil amendments and fertilizers). But the foliar application is an excellent way of supplying plant requirements for secondary nutrients (calcium, magnesium, sulfur) and micronutrients (zinc, manganese, iron, copper, boron, and molybdenum).

Foliar fertilizers help plants compensate for soil deficiencies (soil chemistry imbalance, cold soils, or low soil fertility) during the growing season. Moreover, they help to fortify plants against other types of stress, such as drought, heat, cold, mechanical or insect damage or the onset of disease-susceptible periods.

Application Schedule: Begin your foliar fertilizer applications in early spring. Time the application to encourage and/or enhance critical points in the plant’s growth cycle, i.e. flowering, fruiting, and seed formation. Throughout the growing season, apply to improve nutrient balance as you see fit, during stressful periods and after traumatic events. In the fall, time the application in accordance with the leaf fall.


What you’ll need

  1. Foliar fertilizer – water-soluble powder or liquid form (see STEP 1. below)
  2. Spray tank/Backpack sprayer or bottle
  3. Safety glasses
  4. Water
  5. Spreader-sticker — optional
  6. pH meter – optional


How to Apply Foliar Fertilizers


STEP 1: Choose a fertilizer

Foliar fertilizers come in a water-soluble powder or liquid form. There is a wide variety of foliar feeds to choose from, but in a permaculture orchard/food forest we’ll focus only on the best natural solutions that not only feed the plants but are also beneficial microbes in the soil.


  • Seaweed has a wide range of naturally chelated nutrients, amino acids, and other growth-promoting substances.
  • When applied as a foliar spray it stimulates cell division and promotes larger, healthier root systems and feeds the plants with trace elements including boron, molybdenum, copper, iron, zinc, cobalt, manganese, and selenium in naturally balanced amounts. This, in turn, increases the plant’s resistance to environmental stresses and helps grow better quality fruit.
  • Seaweed extracts are bottled as a concentrated liquid or dried into a soluble powder for foliar application.
  • Application: best applied throughout the growing season starting after the foliage has emerged, stopping with the leaf fall.

Pure neem oil

  • Pure neem oil contains immune stimulants and the fatty acids that play a huge role in countering disease. Also, it has trace amounts of nitrogen, phosphorus, potassium, zinc, copper, iron, magnesium, and manganese.

  • When applied to the ground and major branch structure of the tree it provides food for the soil fungi and protection from the various borers looking to infiltrate the tree trunk. When applied to foliage it helps protect plants from climatic stresses.

  • Application: Start in early spring when the ground begins to warm, continue through the growing season and with a final application in the fall as leaves start to fall.

Liquid fish

  • Liquid fish fertilizer, sometimes called hydrolysate, is made from the fish parts that have not been pasteurized. As such, it contains the fatty acids and enzymes important to beneficial microbes. Besides this it’s also a source of nitrogen.

  • Similar to neem oil, when sprayed directly at the ground and the branches it helps to activate the ecosystem, provide food for the soil fungi, and encourages decomposition. Foliar application boosts the nitrogen, helps to prolong pollen viability, helps to ensure fruit set, and strengthens meristem development.

  • Application: Start in early spring (activates the ecosystem and boosts nitrogen supply) and immediately after fall harvest (boosts decomposition). Avoid spraying in the summer months as it will delay the hardening-off process of fruit trees.


  • Molasses contains all sorts of nutrients that help feed and stimulate beneficial microorganisms, promoting the decomposition and overall activity.
  • The complex sugars found in molasses have humic-like properties that fungi and bacteria readily consume. In addition, blackstrap molasses helps to increase the nutrient density of the fruit.
  • By its nature, it’s sticky, so added to the foliar fertilizer spray mix it will make any introduced microbes “stick” to the leaf surface!


  • Whey is a by-product of the cheese industry, and an excellent source of proteins, lactose, vitamins, and minerals.
  • It’s usually dried into whey powder, and you can add it to any foliar fertilizer spray mix to boost the nutrition of the plant and soil microbes.
  • It also contributes directly to disease suppression as calcium strengthens cell walls and inhibits fungal spore germination.

STEP 2: Prepare the foliar fertilizer spray (mix)

  • You can use single foliar fertilizer or make a mix depending on your needs.
  • Fill the spray tank/bottle – dilute the fertilizer with water according to manufacturer’s directions.
  • To increase the adhesion of the spray to the leaf surface, add a spreader-sticker – a biodegradable vegetable oil surfactant or horticultural oil.
  • Check the spray mixture pH using a pH meter, make sure it is between 5.5 and 6.5 for maximum effect. Apple cider vinegar is excellent for lowering a high pH level.

Recommended rates (Michael Phillips – Holistic Orchard)

Seaweed extract

  • Powder – 8 ounces/225 g (dry weight) per 100 gallons/3,80l per acre
  • Liquid – 2 quarts/2 liters per acre
  • Backpack sprayer – 5 tablespoons liquid kelp per 4 gallons/15 liters spray volume.

Neem oil

  • Early-season/summer months application – 1% concentration
    All other applications of during the growing season – 0.5% concentration.

Liquid Fish

  • Four gallons/15 liters per acre for ground application and 2 gallons/7.5 liters per acre for foliar application.
  • Backpack sprayer – for foliar application use 10 ounces/300 ml of liquid fish per tank.


  • Rates vary between 1 and 4 quarts/1 and 4 liters of blackstrap per acre for ground application.
  • Use 1–4 pints/0.5 – 2 liters per acre for foliar purposes, which translates to ¼ cup/60 ml of molasses in the standard backpack tank mix.

STEP 3: Apply the foliar fertilizer 

  • For maximum absorption, you’ll want slow-drying conditions, in which the dew stays on the leaf surface. Do not apply before or after rainfall or irrigation.
  • The best time to apply the foliar fertilizer is in the early mornings when the air is cool and still. This is preferably at temperatures below 24°C (75°F), since the leaf stomata (pores) close at temperatures above 30°C (85°F.)
  • Spray plants until you see the mixture dripping from the leaves. You’ll need to saturate both tops and bottoms of the leaves. The undersides of the leaves are where most stomata are located.



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