NPK ratios?

Alberto Castillo
Wed, 30 Jan 2008 05:33:19 PST
> Date: Tue, 29 Jan 2008 19:54:36 -0800> From:> To:> Subject: Re: [pbs] NPK ratios?> > Good questions, Robert. I will share a few things I have learned over the> years and hopefully you can apply some of them to your situation.> A few years ago a friend told me that his agriculture advisor told him that> unless you are growing turf or bedding plants the ratio should be about> 1:2:2 or 1:2:3. Otherwise you are wasting the N or possibly risking> toxicity-- in your case it could be that there would have been plenty of N> for your Hipps if you used half the ratio amount of your formulation,> increasing the dilution rate as necessary. Since I learned this and also> observed the results my friend got using such a formula with his orchids,> succulents, etc., I have switched to a rather strange-sounding 5-11-26> hydroponic formula made by Grow More. A bag of about 40 lbs costs about> 25.00. Since using it on a very wide range of plants, including aroids,> orchids, amaryllids, succulents, ferns, etc., I am very happy with the> results. Plants bloom better than before and growth is strong and never> lush. I don't grow commercially so am not concerned with "pushing growth".> > Yes, there is something to the ratio situation that is important here but I> don't know how it works exactly. The three major components work together> chemically to some extent (versus independently), along with the minors, and> the interrelationships between them and with the soil (pH, cation exchange> capacity, etc.) are complex. If you are blessed with good water quality you> have already cleared some major hurdles.> > As far as rates I apply N at between 150 and 200 ppm or a little higher; I> think it could go quite a bit higher, at least occasionally, without any> harm. I fertilize with nearly every watering and so keep the concentrations> low generally-- but note that at 200 ppm N for this formula the K is over> 1000 ppm! Once in a while I apply calcium nitrate separately to supply> calcium, especially to epiphytes.> > A word about nitrogen. Many years ago Fred Meyer told me that amaryllids> like Hippeastrum and many others (but not so much hardier fare like Crinum> or Narcissus) resent N in the form it typically appears in fertilizers: as> ammonia or urea nitrogen. I made the switch to orchid fertilizers such as> Dyna-Grow years ago just to get N comprised of mostly nitrate nitrogen, with> a small percentage of ammonia nitrogen. I bloomed some difficult bulbs when> I did this, plants that had not flowered for 10+ years previously> (Hippeastrum parodii, Paramongaia, etc.). Nitrate nitrogen is worth the> moderate extra cost in my view and it is not difficult to find brands that> use it.> > You should not have to worry about any salt build-up unless you are not> watering thoroughly or your fertilizer is too concentrated and applied too> often. I try to double water plants every time I water and have very little> problems with excess salts.> > Dylan> > On Jan 28, 2008 9:21 PM, rdjenkins <> wrote:> > > I have been wondering about the various ratios of the three main> > nutritional elements in prepared fertilizers and have a few questions that I> > hope someone can help me answer or point me to where I may find them.> >> > This past summer, I switched to a brand-name product to feed my> > Hippeastrums. The ratio I chose was 24-8-16. I had excellent results.> >> > I have two H. papilios in bloom just now: one has three scapes and the> > other has two. I have had both bulbs for just over two years and they are> > the common Dutch run. Both have a scape with three (yes!) blooms in the> > peduncle.> >> > Obviously, the lower proportion of P has had no negative effect and the> > higher N content only helped grow the great foliage and size up the bulbs.> > Contrary to some warnings I received, the foliage wasn't unnaturally lush,> > tender or weak, but was as healthy and as strong as I have ever seen it. And> > contrary to what is often promoted for other non-bulbous plants (higher P> > percentage) and might seem to be called for in Hippis in what seems to be a> > logical and sensible way, my plants had everything they needed to flower> > better than ever with the higher N and lower P ratio.> >> > I know that applying N alone can "push" green growth to the expense of> > floral production in many annuals. One question I have about blooming> > annuals is how much "pushing" occurs as a result of a higher proportion of P> > on the blossoming of annuals? This is more for general interest, since I am> > really more concerned with Hippis.> >> > For instance: If I am feeding a plant 5-15-5, is there something in the> > 1-3-1 *ratio* that "pushes" flowering more than 15-15-15, since the plant is> > getting the same amount of P in both cases? Would it be a matter of the> > plant making use of the more abundant element in the 5-15-5 feed, whereas> > with the 15-15-15, the plant's energy is divided between green and flower,> > so it might have less abundant flowers?> >> > Back to bulbs: As I understand it, the various ratios for blooming plants> > comes out of chemical analysis of the entire plant to find out where the> > N-P-K ends up (as well as observations of differences in color, strength,> > and quality of different plant parts.So, blooms showed higher P content> > and for better blooms more P was prescribed.> >> > How much is "too much"? That is, from this past season's results, 24-8-16> > at a constant dilute feed was obviously good enough to supply what my bulbs> > needed to grow and produce buds, could it still make use of more of any> > element? When is a plant's mouth full and unused elements just stay in the> > soil unused and possibly building up to toxic levels?> >> > Another question: Do the different proportions make a chemical difference> > in the bulb itself or is it all one form that ends up in different> > concentrations depending on target?> >> > I hope you can understand, perhaps between the lines, what I am wondering> > about. Since all the different ratios of NPK cost the same by-the-box for> > me, it isn't a matter of paying for something my plant can't use, but if I> > was preparing my own, cost might or might not be a factor in adding> > essentially unused levels of nutrients.> >> > Robert.> >> >> >> > _______________________________________________> > pbs mailing list> >> >> >> >> _______________________________________________> pbs mailing list>>>
Express yourself instantly with MSN Messenger! Download today it's FREE!…

More information about the pbs mailing list