I have not been happy with blood meal as a soil amendment. The quick
breakdown creates a short-term oxygen demand in the soil. If sufficient
oxygen cannot be supplied, the breakdown becomes anerobic, usually
producing ammonia rather than nitrate. The lack of oxygen alone can be
toxic to roots and the ammonia and PH swings exacerbate the problem. I've
killed a few plants with blood meal.
In addition, the nitrogen is gone in a few weeks. One might just as well
have used urea or (better yet) an encapsulated product like osmocote.
I disperse a little blood meal in the solution that I use for watering.
It is a very week (1/4 tsp per gal) solution of General Hydroponics
"Floragro". That product is low in nitrogen and an added 1/4 tsp of blood
meal evens it out without an instant spurt of nitrogen every time that I
water.
One problem with the dust-fine forms of blood meal is difficult wetting.
The powder may float on the surface and never disperse. A small amount of
soap or detergent cures the problem but I was not sure that cp and other
tender plants would tolerate it. My current method is to pre-mix the
blood meal with the floragro and disperse both in very hot water before
diluting the rest of the way with cool.
If you have cats, they will dig into a pot which has been amended with
blood meal. They knock over my watering can out of curiousity.
I do wonder whether a little bit of blood meal would be appropriate in a
bromeliad or in a pitcher.
Bob Cruder - bcruder@miaco.com