Both are great additions but pound for pound, worm castings are superior. They are considered the Cadillac of composts - relatively high nutrient content, very high populations of beneficial microorganisms, a good source of humic acid and they contain beneficial plant growth hormones (auxins). They enhance seed germination. They also absorb 3-4 times their weight in moisture, contibuting significantly to soil moisture retention and they are heavily populated with both nitrogen fixing and anti-pathogenic bacteria. Although Al makes some very valid points, worms tend not to make great pets :-) I wouldn't trade my bunnies for worms but I would consider both. Since I have a source for as many worm castings as I can use, I opt to keep my bunnies both for their appeal and their poop output.

I can only speak from my experience but in the time Ive had a worm bin I havent harvested the castings, I leave them in the bin and only take some out as I need them so there's always been a high percentage of castings in there. Ive never noticed any problems, the worms are happy and healthy and seem to like it down in the castings where it's always nice and moist If the worms were unhappy or trying to leave then I would suspect a problem but it's never happened

I'm very skeptical that anyone sells pure worm castings. I define a casting as a particle that has actually passed through the digestive tract of a worm. Vermicompost or worm compost is a much more accurate description of what is probably in the bag. Your homegrown VC is probably different from stuff you buy for a number of reasons. I can't remember which forum this came from, but it was posted by: Kelly Slocum On: 2001-09-01. "the feedstocks chosen for producing maximum worm biomass are not always those chosen to produce the best castings for a particular situation, no. keep in mind that castings value is determined largely by the intended end use. if you want the castings to amend your soil for planting a fruit orchard, for instance, the castings you'd most want would be dominated by microscopic fungi, supported in castings produced by a feedstock with a high proportion of carbon material (leaves, wood, paper, cardboard, etc.). were you looking for castings with which to amend soil that will be growing annual flowers the product with the highest value to you would be dominated by bacteria. bacterial castings are produced with feedstocks higher in nitrogen (greenwastes, manures, etc.). castings that have the most generally diverse community of organisms possible are generated from feedstocks with a particular balance of carbon and nitrogen bearing materials. now, studies show that, provided appropriate moisture and aeration are maintained, manure is the material that produces the greatest worm biomass. manure alone is not going to produce castings with the most diverse numbe of organisms, however, needed for a high qualtiy general purpose product." Note the tacit implication that NPK is not what makes VC a valuable soil amendment. Search "soil food web" and you'll have plenty of reading material. Cheers, Andrew

One of my biggest Meyer growers fertilizes all his trees (in ground, of course) with a tea made from worm castings distributed through a drip irrigation system. I put worm castings on all my garden roses and citrus a couple of times per year, just as a bonus; when I create my container soil I also include worm castings. Worm castings and worm casting tea are excellent for citrus; but you have to put quite a lot; same with cow manure... excellent; but you have to put a lot.