fertilizing bulbs

J.E. Shields jshields@indy.net
Fri, 08 Apr 2005 13:46:50 PDT
Hi all,

I suggest we consult the following:

A.R. Rees, "The Growth of Bulbs" Academic Press, London & New York, 1972, 
311 pp.

A. De Hertogh & M. Le Nard, "The Physiology of Flower Bulbs" Elsevier, 
Amsterdam, London, New York, Tokyo, 1993, 811 pp.

This was gleaned from de Hertogh & Le Nard:

For Narcissus, phosphate and potassium are applied at planting and then 
nitrogen later as a top dressing just before plant emergence.  Dutch usage 
seemed to average 50-75 kg/hectare ( 1 kg = ca. 2.2 pounds; 1 hectare (ha) 
= about 2.5 acres) nitrogen in winter; 75-125 kg/ha nitrogen in spring; 100 
kg/ha phosphate (as P2O5), and 220 kg/ha potassium (as K2O), and 40-60 
kg/ha magnesium.

Tulips are given fall and spring fertilizer applications:  Ammonium in 
fall; a small but measurable uptake of nitrogen occurred in winter.  The 
spring application is nitrate (NO3-) applied at leaf emergence; uptake was 
rapid.  Excessive nitrogen (more than 250 kg/ha) caused a decrease in bulb 
yield.  Potassium and phosphate fertilizers have not be studies so thoroughly

Lilium were fed with 75-150 kg/ha nitrogen in mid-May or split between 
mid-May and mid-June applications.  The split applications yielded large bulbs.

Use of potassium fertilizer in magnesium-deficient soils will exaggerate 
the magnesium deficiency.

Unless you are doing a large scale study of bulb yields, it probably won't 
matter what you use or when you use it to feed bulbs.  It is in the tricky 
ones where you need to experiment and to be aware of what you are 
doing.  Field trials do not have much relevance to pot culture, in my own 

Jim Shields
in spring-like central Indiana

At 11:59 AM 4/8/2005 -0400, you wrote:
>But here's another thought: I've been thinking about this question of
>fertilizing bulbs a bit lately, and this idea popped up: why not see what
>the experts, the real experts whose livelihood depend on the results, have
>to say about it.
>I have not yet tracked down the experts, but for starters I'm considering
>USDA publications on onion culture and Easter lily culture. Those are both
>bulbs, and in the case of onions, bulbs in the big business sense. I'll bet
>there are plenty of studies which have determined precisely when those bulbs
>need fertilization and just what nutrients they need when.
>Jim McKenney

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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