J.E. Shields jshields104@insightbb.com
Tue, 21 Oct 2003 10:36:48 PDT
Hi all,

My basic premise is that facts are vastly superior in practical value to 
old wifes' tales.  So I based my Hippeastrum culture on advice from Len 
Doran back in the 1970s.  Beyond that, I consult the book by de Hertogh and 
Le Nard, "The Physiology of Flower Bulbs."

Len said to avoid bone meal because most of these exotic bulbs are very 
prone to rotting, and bone meal encourages the growth of fungi and 
bacteria.  Gordon Summerfield is quite right, bone meal is to be avoided if 
you value your bulbs.  Organic potting mixtures and plant foods are to be 
avoided when growing bulbs like Hippeastrum, since these bulbs are so 
easily attacked by bacteria or fungi.  Organic plant foods require 
bacterial or fungal digestion to become available to plant roots.

Len further recommended that all nitrogen be in the form of nitrate, also 
to discourage fungal growth.  Potassium nitrate, calcium nitrate, and 
magnesium nitrate would all be quite good sources of nitrogen.

De Hertogh and Le Nard make the point that most bulbs need much more 
nitrogen and potassium than phosphate. Based on this, I suspect that 
potassium nitrate probably comes very close to being an ideal bulb 
fertilizer.  Summerfield is again right, bulbs need relatively little 

Since I use soilless mixtures based on Promix and amended with sand and 
granite chick starter grit, I think my bulbs can tolerate the soluble 
Peters 20-20-20 (with micronutrients) that I currently use.  However, I 
think I could probably shift to something like 20-5-20 and still have 
healthy, vigorous bulbs.

Just my 2 cents' worth.

Jim Shields
in central Indiana (USA)

At 08:49 AM 10/20/2003 -0700, Mary Sue wrote:
>Dear All,
>The topic of the week this week is fertilizers. In my Gordon Summerfield 
>summary I included his prescription for fertilizing and am repeating it 
>here as a starting point:
>"He advised avoiding super phosphates which he says many of the bulbs hate 
>and feels bone meal has no value at all. Also he doesn't think foliar 
>feeding is helpful. Here is his formula for feeding:
>Magnesium sulfate--If leaves are yellow or the tips brown need this
>Ammonium sulfate--Provides nitrogen. He says contrary to opinion bulbs 
>need nitrogen
>Potassium sulfate--Helps the new leaves, if they are purplish they need this
>Kelp--This helps with formation of the bulb for the next season. He adds 1 
>Tablespoon to a gallon of water in the middle of the growing season.
>Both he and Henry Pauw add small amounts of these and dissolve them in 
>water instead of mixing them in the soil."

Jim Shields             USDA Zone 5             Shields Gardens, Ltd.
P.O. Box 92              WWW:    http://www.shieldsgardens.com/
Westfield, Indiana 46074, USA
Tel. ++1-317-867-3344     or      toll-free 1-866-449-3344 in USA

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