choosing fertilizers - fir bark treatment

[shaelyn]

hi all,

I don't have any fertilizer yet for my orchids, and I've been reading up on what would be best. Ive been reading that high nitrogen is best for orchids in fir bark (such as mine are.) I'm looking at Jack's fertilizers right now, so I see 30-10-10 formula recommended.
I've also glanced at the bloom boosters...which are 10-30-20...eek, low nitrogen!
so I guess what I'm wondering is, when I'm ready to use a bloom booster...should I use the low-nitrogen stuff? should I mix it with my regular? if I did a half-and-half solution, that'd end up being a 20-20-15 ratio...right? 20-20-20 is all-purpose...would I be better off just getting the all-purpose as a substitute instead, when I want to use a bloom booster? is there something I'm missing, or is my mind running wild with stuff that's over my head right now? LOL

[Ray]

What you've been reading is rehash of old, outdated, and mostly incorrect information.

Yes, the micro organisms that break down bark consume nitrogen as they do. However, in fresh bark, their population is so low, that the need to supplement the nitrogen is unnecessary. Let the bark get to a serious state of decomposition, and that will change, although at that point, you will have suffocated the roots of your plants and killed them. That said, a 30-10-10 is not THAT high in nitrogen, so if you feed at low rates, it's fine.

Bloom booster do not boost blooming. The best blooming is a plant that has been given optimum culture, with feeding being a minor aspect of that. Back when it was normal to feed very heavily with very high nitrogen formulas the excess nitrogen stopped plants from blooming. If you dilute the nitrogen in the formula by adding cheap phosphorus compounds, the lessen the burden on the plant, allowing it to bloom. Then the marketing folks got hold of that, and "boosters" came into being.

[tucker85]

If you ask 10 orchid growers, what fertilizer to use, you'll get 10 different answers. You'll also get 10 different answers about how to use them. Jack's 30-10-10 is a perfectly good fertilizer for orchids in fir bark. You're correct that many experts recommend high nitrogen fertilizers for orchids grown in fir bark. It's a good idea to decrease the nitrogen in the fall. Bloom booster has been getting negative press for a few years now but I like to use it occasionally, starting in November. You probably want to fertilize once a week in the summer and decrease to once every two weeks in the fall and winter. Starting in November (or whenever it starts to get cool) you could alternate a bloom booster with a 50/50 mix of bloom booster and Jacks every two weeks. High nitrogen isn't good in the fall when the plants aren't growing much. It can keep them from blooming. This is just one suggestion. There are many ways of achieving good results. But the basic principle is more nitrogen in the spring and summer and less nitrogen in the fall and winter. Good luck.

---------- Post added at 01:43 PM ---------- Previous post was at 01:37 PM ----------

I posted my message at the same time that Ray posted his so I didn't get to read it before replying. He's made some excellent points and he's an expert when it come's to fertilizer. In fact I read an excellent article about fertilizers by Ray, last year, in the International Phalaenopsis Alliance newsletter.

[camille1585]

Or simply use a balanced fertilizer, year round. Basically any fertilizer (at an orchid friendly dosage) is better than no fertilizer at all, and as Tucker says, 10 different people will give you 10 different answers! I like balanced ones because I know there's not too much of anything, and there's no need to change fertilizers throughout the growing season. The only thing I do is add some epsom salts, since my tap water has really low magnesium levels.

[shaelyn]

I appreciate the help guys, thank you so much!

[Wild Orchid]

Originally Posted by camille1585

Or simply use a balanced fertilizer, year round. Basically any fertilizer (at an orchid friendly dosage) is better than no fertilizer at all, and as Tucker says, 10 different people will give you 10 different answers! I like balanced ones because I know there's not too much of anything, and there's no need to change fertilizers throughout the growing season. The only thing I do is add some epsom salts, since my tap water has really low magnesium levels.

Hi Camille,

Can you specify what you consider an "orchid friendly dosage"?

Thanks!

[Ray]

I hope she won't mind if I jump in on that question...

I have been doing a lot of research into orchid nutrition lately, looking at it from the role of the individual nutrients, how they interact within the plant, how well they are stored by the plant for redistribution to other parts of the growing tissues, and how available they are in the ecosystems in nature.

To summarize - most plant nutrient research has been done on food crops like rice and corn, which grow orders-of-magnitude faster than orchids, and originate in totally different natural ecosystems, so have different (much greater) nutrient demands. The fact that the vascular fluids of orchids tend to be much more dilute (on the order of 25%) is another indicator that the nutritional demand ought to be lower.

The extremely small amount of research on epiphytes suggests that the nutrient supplies in their natural environments are 1) meager, 2) more-or-less constant, 3) far less balanced than that terrestrial plants see, favoring N over P & K, and 4) calcium and magnesium - taken together - are very important. There is supposed to be an article in the March AOS magazine on this subject - not mine, but I have contributed.

So based upon that, I have surmised - and am using fertilizer almost every time I water, but at a concentration of at most, 50 ppm N. I have been feeding my plants at that rate for over a year now ( K-Lite formula), and am quite pleased.

If you divide 4 by the %N on your fertilizer label, the result is the teaspoons per gallon to mix for 50 ppm N. for you metricated folks, 5.2 / %N = ml/L.

[james mickelso]

Ray, let me get this straight. 4/.2=20. So you say to mix 20 teaspoons of a 20/20/20 balanced fertilizer in a gallon of water and fertilize with that? Seems awefully high a dosage to me. Is this for any 20/20/20 fertilizer such as one like Growmore? Or should the formula be 4/20=.2 teaspoons? Please clarify for those of us who are math deficient. A long time ago I read a book on orchids (brazilian laelias) by someone (a doctoral student I believe) who described how orchids in the jungles of Brazil got their nutrition. During the rainy season, when there was a lot of rainfall, the orchids had all the nitrogen they wanted but little phosphorus or potassium due to it being leached out of the environment by the high rainfall. Then when the rainfall lessened the orchids started getting less nitrogen but as a ratio more phosphorus and potassium which was released slowly from the decaying leaf litter (and dust from across the atlantic) and guano in their environment. This the author stated was why a switch to a higher p and k as a ratio to n was needed and the plant was genetically designed to switch. Once the pseudobulbs had matured and stored up all their fat (nitrogen/starches) they needed then they used the increasing availablity of p and k to initiate inflorescence.The dry season being when the moths and flies and bees became abundant. Any new research on this topic? I'm pretty sure this was funded in part by AOS and if my feeble brain is correct, this was in the late 80's or early 90's. I think he stated that without the increasing ratio of p/k to n the plant hadn't a mechanisim to initiate inflorescence and this was why a high ratio of n to p/k would keep the plant from initiating inflorescence. Your thoughts on this please.

[rangiku]

I'm thinking Ray wants you to do the latter: divide 4 into 20 for a 1/5 of a teaspoon. 1/4 of a teaspoon would be 75 ppm.

[Ray]

Rangiku is correct. Divide by the percentage as stated on the label, not the decimal equivalent.

I guess that the issue I have with the conclusion of that study comes from the assumption that the nitrogen comes from the canopy during rainfall, while the other nutrients are from other sources, and are available at all times.

First of all, we should consider that plants only take up nutrients when they are aqueous ions. If there is no rain and everything is dry - as does happen in habitats that no so coincidentally are the indigenous homes of plants needing a "winter rest" - there is no mineral availability for the plants. (I think the fact that those plants can bloom if kept wet but unfed in S/H culture proves it is the stoppage of nutrition, not water, that is the key to them).

While it is correct that the drainage from the canopy contains nitrogen, that is not all it contains. Pretty much all of the nutrients in the forest are exuded by the trees, so drain to the orchids. Sure, there may be some in the collected detritus, animal droppings and fungi around the root system, but that is not their sole source, and as I mentioned above, if they are dry, they are not providing any nutritional value.