Hydroponics PERLITE

Orchid Culture
PLANT GUIDE
The Schundler Company
150 Whitman Avenue
Edison, New Jersey 08817
732-287-2244 www.schundler.com



GROWING ORCHIDS IN PERLITE

by
Dr. Wally Thomas
and Barb Thomas
Charles Island Gardens
West Vancouver
Canada


Odontioda SEA NYMPH Odontioda SEA NYMPH 'Island Rainbow', H.C.C. A.O.S, hydroponically grown in 100% perlite.
This Plant Guide summarizes 5 years of outstanding success in growing orchids at Charles Island Gardens using the perlite reservoir technique with intermediate size perlite. This method, by which all major genera of orchids can be grown, allows for a constant supply of nutrient to the plant by taking advantage of the unique capillary action of perlite. An outstanding characteristic of this method of culture is that one cannot over water and that there is always excellent aeration. Table 1 compares the excellent properties of perlile with those of other commonly used growing media.

Additionally, perlite is a naturally occuring material. Horticultural perlite (about 1/8 inch, 3 mm in diameter) is pretreated by pouring perlite into a tub of water and fertilizer solution. The perlite is pushed into the water several times and the floating perlite is skimmed off. This wet perlite is a wonderfully easy material with which to pot. Such pretreated perlite shows no evidence of compaction after three years.



TABLE 1 - COMPARATIVE PROPERTIES OF GROWING MEDIA COMMONLY USED WITH ORCHIDS
  BARK PEAT ROCKWOOL PERLITE
Ph of Medium
Fertilizer Control
Leaching
Aeration
Disposal
Health Hazard
Sterility
Management
Simplicity
Weeding
Availability
Cost
Ease of Potting
Repotting Time
Nutrient
Overwatering
Rewetting
Cation Exchange
Buffering
Slightly Acid
Good
Easy
Good
Easy
Care
No
Fairly Easy
Fair
Fairly Easy
Good
Varies
Good
1-2 Years
Minimum
Yes
Fair
Yes
Slight
Acid
Good
Fair
Fair
Easy
Care
No
Fairly Easy
Fair
Fairly Easy
Very Good
Varies
Good
1-2 Years
Minimum
Yes
Fair
Yes
Acid
Slightly Alk.
Good
Fair
Fair
Problem
Care
Yes
Fairly Easy
Fair
Fairly Easy
Fair
Varies
Good
1-2 Years
Nil
Yes
Poor
No
No
Neutral
Very Good
Very Easy
Very Good
Easy
Care
Yes
Very Easy
Very Simple
Very Easy
Very Good
Competitive
Very Good
2 Years+
Nil
No
Easy
No
No

Potting and Repotting

Ordinary pots may be converted for reservoir use by inserting a cup in the bottom. Specific reservoir pots and saucerless hanging baskets are excellent. To plant a 10 inch (25 cm) sauce rless basket, the basket is filled to 2 inches (5 cm) from the top with perlite. Thirty to forty seedlings are planted and the surface covered with pea gravel. To ease the transition, cling wrap material is wrapped around the hanging wires leaving an opening at the top. The plants are bottom watered for the first six weeks, after which time the wrap is removed and the plants treated normally. Mature plants are best repotted when new growth has just started. Plants are set a little deeper than with other media and pea gravel is used to hold the plant firmly in place as well as to decrease evaporation. Repotting is only required when space for new growth is needed. There is no plant setback when repotting from perlite to perlite.

Bed Growing

Eight inch (20 cm) deep beds are constructed of wood, lined with 6 mil. black polyethylene with an overflow outlet at 1-1/2 inches (4 cms) from the bottom to provide a reservoir. Overflow solution is collected for recycling.

Watering/Fertilizer

Pots should be heavily watered before they dry. One cannot overwater with the perlite system. Charles Island Gardens has experienced no disease in 5 years and the system offers the potential for simple and inexpensive automation. A complete hydroponic fertilizer suitable for most orchids is shown in Table 2.

TABLE 2 - CHEMICAL COMPOSITION OF FERTILIZER SOLUTION
N
P
K
Ca
Mg
SO4
49 ppm
18 ppm
76 ppm
42 ppm
14 ppm
18 ppm
Fe
Cu
Mo
Zn
Mn
B
0.37 ppm
0.0035 ppm
0.05 ppm
0.11 ppm
0.33 ppm
0.10 ppm
These levels may be achieved by using, by weight, one part Ca(NO3)2 to 2 parts 7-11-27 (Plant Prod*) or 2 parts 5-11-26 (Peters), diluted according to your proportioner to yield an E.C. of 600 µmhos. 7-9-5 (Dyna-Gro) at an E.C. of 600, although low in calcium and magnesium, provides satisfactory growth. For most orchids, the final diluted fertilizer solutions should have a pH of 5.8 to 6.4.

* Registered trademark of Plant Products Co., Ltd.
Registered trademark of W.R. Grace Co., Ltd.
Registered trademark of Dyna-Gro Corporation

Photos
Odm. crispum 'Island Shirley'


For more information about these uses of perlite and vermiculite, please call or contact us at:

The Schundler Company
150 Whitman Avenue
Edison, New Jersey 08817
(ph)732-287-2244 (fax) 732-287-4185
www.schundler.com
email: info@schundler.com

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