Articles
PHALAENOPSIS MINERAL NUTRITION
Article number
878_41
Pages
321 – 333
Language
English
Abstract
Phalaenopsis is the most important potted orchid around the world.
It has a long juvenile period.
High fertilizer concentrations in general accelerate vegetative growth and fast accumulation of the total leaf area to have plants mature quickly.
In most bark mixes, fertilizers providing 200 mg/L nitrogen (N) promote growth over lower concentrations.
High fertilizer concentrations ensure high flower count but do not always increase flower size. Phalaenopsis needs at least 50% of the N in the nitrate form for improved growth and flowering, regardless of being planted in a bark mix or in sphagnum moss.
N concentration close to 300 mg/L, particularly in the ammonium form, has been reported to delay spiking and flowering to a certain extent.
Phosphorus (P) at 25 to 50 mg/L is adequate for optimum growth.
P concentration in the nutrient solution does not affect flower size.
Starting to apply high levels of P one month before spiking does not further enhance flowering.
Fertilization may be terminated completely when the inflorescence has reached 10 cm in length or at first flower opening without affecting flower count.
Fast-growing larger plants in a bark/peat mix have lower P concentration in their leaves than the slow-growing smaller plants in pure bark, but the entire plants in both media have similar total amounts of P. When using high N levels (200 mg/L or higher), potassium (K) must be at 200 mg/L or higher for obtaining healthy foliage, increased flower count, and larger flowers than lower concentrations.
Plants under low K (0 to 100 mg/L) appear healthy when vegetative; but, as soon as being induced to enter the reproductive phase, yellowing and abscission of the lower leaves occur.
Foliar feed alone does not provide adequate amounts of nutrients for Phalaenopsis. Moisture tension of the tightly packed sphagnum moss remains at or higher than -20 kPa until 90% of the water is lost, compare with 55% water loss in a peat/diatomite mix; thereby, providing higher amount of available water to roots.
The pH of the sphagnum moss in growing containers is often between 3.0 and 3.5. Yet, this low pH does not seem to negatively affect plant growth or cause apparent toxicity from the accumulation of certain micronutrients in plants.
It has a long juvenile period.
High fertilizer concentrations in general accelerate vegetative growth and fast accumulation of the total leaf area to have plants mature quickly.
In most bark mixes, fertilizers providing 200 mg/L nitrogen (N) promote growth over lower concentrations.
High fertilizer concentrations ensure high flower count but do not always increase flower size. Phalaenopsis needs at least 50% of the N in the nitrate form for improved growth and flowering, regardless of being planted in a bark mix or in sphagnum moss.
N concentration close to 300 mg/L, particularly in the ammonium form, has been reported to delay spiking and flowering to a certain extent.
Phosphorus (P) at 25 to 50 mg/L is adequate for optimum growth.
P concentration in the nutrient solution does not affect flower size.
Starting to apply high levels of P one month before spiking does not further enhance flowering.
Fertilization may be terminated completely when the inflorescence has reached 10 cm in length or at first flower opening without affecting flower count.
Fast-growing larger plants in a bark/peat mix have lower P concentration in their leaves than the slow-growing smaller plants in pure bark, but the entire plants in both media have similar total amounts of P. When using high N levels (200 mg/L or higher), potassium (K) must be at 200 mg/L or higher for obtaining healthy foliage, increased flower count, and larger flowers than lower concentrations.
Plants under low K (0 to 100 mg/L) appear healthy when vegetative; but, as soon as being induced to enter the reproductive phase, yellowing and abscission of the lower leaves occur.
Foliar feed alone does not provide adequate amounts of nutrients for Phalaenopsis. Moisture tension of the tightly packed sphagnum moss remains at or higher than -20 kPa until 90% of the water is lost, compare with 55% water loss in a peat/diatomite mix; thereby, providing higher amount of available water to roots.
The pH of the sphagnum moss in growing containers is often between 3.0 and 3.5. Yet, this low pH does not seem to negatively affect plant growth or cause apparent toxicity from the accumulation of certain micronutrients in plants.
Publication
Authors
Y.-T. Wang
Keywords
fertilizer, nitrogen, moth orchid, phosphorus, potassium, root substrate, water relations
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