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INDOOR PLANT FERTILIZING

BY BRUCE ZIMMERMAN

The demand for fertilizer by an indoor plant starts with where it evolved. An indoor plant that evolved in the thin poor soils of the tropics with their heavy leaching by the large volume rainfalls and the constant rapid decomposition of plant and animal litter will not have the same fertilizer demand as that of an indoor plant that evolved in a xerophytic environment of poor sandy soils and low rainfalls.

 The light levels that a plant is growing in will affect the demand by the indoor plant for both the quantity and frequency of fertilizer. Light is the energy that drives the plants engine that converts Carbon (45%), Hydrogen (6%), and Oxygen (43%) into usable simple sugars. The remaining 6% is made up by all the other nutrients.  Without light there is less demand for all of these elements.  This understanding is important when moving plants into lower light (acclimation) or when the light levels drop due to seasonal changes.

 Since light plays such a large role in a plants growth and it’s fertilizer demand the first step in successful fertilizing is to dust and clean the leaves. Then the pH of the water and the growing medium should be correct.  The usual range for both is between 6.0 and 7.0 while a pH below 6.0 will increase the availability of both the essential micronutrients

(Manganese, Good Long Term Indoor Fertilizer iron, copper, zinc, and the ten others) as well as the toxic micronutrients such as fluoride, boron, and sodium.  The application of excess fertilizer will increase the unusable nutrients in the growing medium and these salts burn the root hairs causing a reduction of water and nutrient uptake.  So learn this truth: fertilizer is not a medicine to cure what ills a plant. Fertilizer will not fix such environmental stresses as incorrect watering, light levels, insects and diseases.

 Plants use the macronutrients in the ratio of 3 (N) : 1 (P) :  2 (K).  The manipulation of these numbers can help a plant produce more foliage, flowers and roots.  Excessive use of plant nutrients Varigated Weeping Figcan also kill. So tread lightly.

 

 General Plant Appearances:

 Low Nutrient levels:

  • Slow growth
  • Leaves are pale with chlorotic spots
  • Flowers are absent or small and of poor colour

 High Nutrient Levels 

  • Leaves are wilted
  • Whitish salts buildup on soil surface and/or pot
  • Growth is lanky
  • Necrotic areas on the leaves with brown edges (dead spots).

Approximate ppm /gal using 24-8-16 water soluble fertilizer:
1/4 teaspoon = 75ppm N

LOW LIGHT CONDITIONS:   50-150 foot candlesLow Demand Fertilizing for Peace Lily

 Low Demand Plants Use    75ppm                        

Medium Demand Plants Use    150ppm

High Demand Plants Use      225ppm

 MEDIUM LIGHT CONDITIONS:   100-200 foot-candles

 Low Demand Plants Use    100ppm

Medium Demand Plants Use     225ppm

High Demand Plants Use   300ppm

 HIGH LIGHT CONDITIONS:    200-500 foot candlesLow Demand Fertilizing Calathea

 

Low Demand Plants Use    150ppm

Medium Demand Plants Use    250ppm

High Demand Plants Use    350ppm

 

 VERY HIGH LIGHT CONDITIONS:    500-1000 plus  foot candles

 Low Demand Plants     Not Applicable

Medium Demand Plants   300ppm

High Demand Plants    375ppm

 

Common Name

Botanical Name

Fertilizer Demand

Alexander Palm   Ptychosperma elegans   High  
Anthurium

Anthurium Spp. ‘Kingston’

Low
Anthurium Anthurium Spp. ‘Crystal Hope’   Low
Anthurium   Anthurium Spp. ‘Nicoya’   Low  
Aralia ‘Fabian’   Polyscias scutellaria ‘Fabian’   Medium
Black Aralia   Polyscias guilfoylei   Medium 
Black Olive ‘Shady Lady’   Bucida bucerus ‘Shady Lady’   Medium
Cast-Iron Plant   Aspidistra elatior Low  
Chicken Gizzard Aralia   Polyscias crispate ‘Chicken’   Medium  
Chinese Evergreen   Aglaonema hybrid ‘Green Lady’   Low  
Chinese Evergreen   Aglaonema hybrid ‘Royal Ripple’   Low  
Chinese Evergreen   Aglaonema hybrid ‘Queen of Siam’   Low  
Chinese Evergreen   Aglaonema hybrid ‘Jewel of India’   Low  
Chrysanthemum   Chrysanthemum spp. Medium
Common Oleander   Nerium oleander Medium
Corn Plant   Dracaena fragrans ‘Massangeana’   Low
Croton   Codiaeum variegatum ‘Petra’   High
Devil’s Ivy   Epipremnum aureum ‘Golden Pothos’  

Medium

Dracaena ‘Lemon Lime’ Dracaena deremensis ‘Lemon-Lime’   Low

Dracaena ‘Janet Craig’

Dracaena deremensis ‘Janet Craig’   Low  
Dracaena Reflexa   Dracaena reflexa ‘Song of India’   Low  
Dumb Cane   Dieffenbachia hybrid ‘Camille’   Medium  
Elephants Ear Alocasia amazonica Medium
Fern   Nephrolepsis Spp. Medium  
Ficus ‘Alii’   Ficus maclellandii ‘Alii’   High  
Ficus ‘Amstel King’   Ficus maclellandii ‘Amstel King’ High  
Gardenia   Gardenia jasminoides Medium
Hawaiian Schefflera Schefflera arboricola Medium
Hibiscus   Hibiscus spp. High
Ivy   Hedera helix Medium
Kentia Palm Howeia forsteriana Medium
Lady Palm Raphis excelsa Medium
Madagascar Dragon   Dracaena marginata ‘Tri-Colour’   Very High
Madagascar Dragon Tree Dracaena marginata ‘Magenta’   Very High
Mandevilla   Mandevilla amabilis (hybrid)   Medium
Ming Aralia   Polyscias fruiticosa ‘Ming’   High
Nephthytis

Syngonium podophyllum ‘White Butterfly’  

Medium
Norfolk Island Pine   Araucaria excelsa   Low 
Peace Lily   Spathiphyllum Spp. ‘Sonya’   Low
Peruvian Cactus   Cerecus peruvianus Low
Poinsettia Euphorbia pulcherrima Low  
Prayer Plant Maranta leuconeura Low  
Rubber Plant   Ficus elastica ‘Melany’ High
Satin Leaf   Chrysophyllum oliviforme ‘SatinLeaf’    Medium
Snake Plant Sansevieria zeylanica   Low  
Spider Plant Chlorophytum comosum   Medium
Tupidanthus   Tupidanthus calyptratus Medium
Umbrella Tree   Brassaia actinophylla   High
Var. Hawaiian Schefflera   Schefflera arboricola ‘Goldfinger’   Medium
Var. Weeping Fig   Ficus benjamina ‘Snow’   High
Washingtonia Palm   Washingtonia robusta Medium
Wax Plant Hoya carnosa Low
Yucca   Yucca elephantipes Medium

Remember that more indoor plants are killed by over fertilizing than by under fertilizing.

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