ROCKWOOL: As Potting Medium

It is inert, a spun rock, like fiberglass, it comes in three grades -- fine, medium, coarse -- and in both absorbent and non-absorbent types, including Grodan horticultural grade, available in 3 or 4-inch growing blocks which are absorbent; the advantages claimed for it include -- sterility, inertness, ease of repotting, its maintenance of a 15% air space, it provi des for fertilizer control; its disadvantages are its high cost originally and the care required to achieve correct fertilizer levels; it has to be kept wet; for odontoglossums it requires a 20-20-20 fertilizer. RMH

It is used for growing cymbidiums. A85-841

It is volcanic rock melted down into cot tony fibers, it is inert, sterile and does not decompose; po11 ing-on is possible without di sturbing the root ball; the pH is perfect when watering with commercial 20-30-20 fertilizer; advt. A88-332

This is the name given to several commercial insulating materials on which orchids can be grown by adjusting the watering and fertilizing practices. A86-923

Use a fine absorbent type and make sure it never dries out because the salt concentration buildup can lead to leaf scorch; it must be watered well. RMH

Rockwool	Comments
ROCKWOOL: Absorbs Fertilizers During a dark winter the Electric Conductivity can double in the nutrient solution, so make it half normal strength; urea fertilizer applied to it hardly has a chance to be used before it is washed out again, before bacterial action can make it available to the roots. OA87-163; 201	0
ROCKWOOL: With Perlite as Potting Mix A two year commercial experiment growing in a mix of water-repellent rockwool and perlite, with trial balances of nutrients and trace elements was termed a success; advt. A87-Jy-xiv	0

Rockwool

Comments

ROCKWOOL: Absorbs Fertilizers During a dark winter the Electric Conductivity can double in the nutrient solution, so make it half normal strength; urea fertilizer applied to it hardly has a chance to be used before it is washed out again, before bacterial action can make it available to the roots. OA87-163; 201

ROCKWOOL: With Perlite as Potting Mix A two year commercial experiment growing in a mix of water-repellent rockwool and perlite, with trial balances of nutrients and trace elements was termed a success; advt. A87-Jy-xiv

ROCKWOOL: As Potting Medium

by Robert M. [Bert] Hamilton (Compiler)

Originally published in The Orchid Doctor in 1980 and 1988

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