S/H, Urea and Micronutrients

[krpot]

I eventually would like to switch every houseplant I have to s/h. I've been reading up on it and it seems like the best way to grow indoors. I have a few questions.

I bought a urea fertilizer a while back and have yet to use it because urea is not good for orchids because it takes a long time to convert to a form of nitrogen able to be absorbed by orchid roots. Is this true? And second question: If that's the only reason why one's not supposed to use it, would that mean it would be ok for orchids grown in s/h? Because the nutrient solution is available to the plant constantly... Sorry if this is a silly question, I'm new to this.

Sorry, question two: I went to the local hydro store (I know I'm lucky I have one in town) and they kept telling me I need a micronutrient solution to grow anything in s/h and that simply NPK is not all plants need. What exactly are these micronutrients that my plants need? And aren't they in all orchid fertilizer?

I'm trying to switch a couple houseplants to s/h at the moment and I was wondering if any of these current fertilizers I have would work for them. The hydro fert is expensive and I really would not prefer to buy another type of fertilizer if I have something that would suffice.

[kmarch]

krpot, can you please clarify something? Are you talking about orchids in this post or other house plants?

[Phalcycle]

Ferts. that contain urea are not used on orchids, because like you said, they dont have the time to actually use it. It would wash away, and be a waste. Its not bad for it, but just a waste because it can't be used.

I dont grow much in S/H, (only to test expereriments)
and the way I grow them is I have a resevoir on bottom, and it is always filled with water, to the holes on side. I flush every other feeding.
I dont't recommend a constant nutrient because too much fert can be problem

[JLu]

Urea fertilizer is no more useful for SH than for any other medium. Used correctly SH pots are flushed completely every few days with water. Even if that is not done (and it should be done), each watering displaces the liquid in the pot. Urea is fine outdoors on dirt, not for potted plants.

Your hydro store is correct. There are many (13-16 depending on the source) nutrients required by plants beyond N-P-K. I suggest you do some reading on the subject of plant nutrition. First Rays web site is a good place to start since you are interested in SH also. Two notes of caution...SH is a legitimate method, but it is not a panacea nor without pitfalls. It works very well with some stuff and not so well with others. You still need to understand what the heck you're doing. There is no substitute for knowledge. Second note ....be sure you know exactly what SH is. It is a method that uses a small liquid reservoir at the bottom of the container and usually a LECA medium. It is not growing in LECA without a reservoir (which BTW I have found more useful that strict SH). Bonus note...if you have no fertilizer of choice try MSU from Ray...get the right one.....pure water or tap water formula. I have NO financial interest in either First Rays or Green Care. I just use MSU fertilizer which I actually buy directly from Greencare (but in small quantities Ray is a better source).

I know that I probably irritate some people by saying this over and over, but internet forums should not be your first resource for information. There is to much uninformed BS. For example, some lady just informed me seriously that her watering habits were the result of her work schedule and sleep habits, as if that had any relevance to the subject of growing plants correctly. Try books to learn the basics of what you want to know and then discuss the issues with others on the internet if you wish. If you understand the basic stuff, you can then sort out the ideas you see on the forums and make use of the experiences of others who have tried whatever you are interested in doing.

[-k-]

Originally Posted by JLu

I know that I probably irritate some people by saying this over and over, but internet forums should not be your first resource for information. There is to much uninformed BS. For example, some lady just informed me seriously that her watering habits were the result of her work schedule and sleep habits, as if that had any relevance to the subject of growing plants correctly.

JLu: Understanding ones audiance is something that should be decerned when providing advice, lest we forget the obstacles of daily life and the balance we work to achieve.

[krpot]

kmarch- I apologize for being vague. I was talking about both, well plants in general in s/h.

Phalcycle- Thanks I'm going to give that urea fert away or something then, because I don't have a garden. I'd read on this site before that in s/h that orchids don't need constant nutrient, then the woman at the hydro store said differently. I'm assuming because orchids store food in their roots.

JLu- Thanks, I'll check out that website and check out some books at the library before diving into this. I was wondering about watering in s/h whether you're supposed to wait until the water in the reservoir evaporates or to flush out the pot more frequently. Yeah, all this macro/micro nutrient stuff is complicated. My orchid fert (Better Gro) has I think 9 ingredients listed.

I agree about internet sources. I was on a hydroculture(s/h) website that I think it quite popular(not going to name it) and the site owner said she uses NPK fert (no micronutrients) for everything she has in s/h. It threw me for a loop because I had the understanding that micronutrients had to be provided.

[krpot]

I haven't been able to find any books on hydroculture alone, but plenty on hydroponics with chapters on macro & micro nutrients. Learned today that pH is waaaayyyyy more important than I had realized. After that I tested my tap water's pH and what do you know IT'S AT 8.4!! it's my understanding that orchids (well phals and dens at least) need around 4.5-6.0 right?

[Ray]

A JLu mentioned, spend some time at my website. Yes, it is a commercial site, but more than 90% of the content is intended to be a free education to folks who want to use it. The "Free Information" page contains over 100 articles.

I strongly recommend Bill Argo's 5-part series on plant nutrition (the "primer" on that free info page). It may be more than you want to know, but will leave you with a good understanding of what's important, even if you don't necessarily grasp the "why" part.

Yes, pH is important, but HOW important will depend upon many things. The term "alkalinity" is used to describe the solution's resistance to pH change by the addition of acids. Your tapwater may have a pH of 8.4, but what is it after the addition of fertilizer or once it is in contact with your potting medium? It might come into the preferred zone easily - or not. I'll give you an example of a common mistake folks make about pH:

Like many, I use pure water (via reverse osmosis) for my orchids. As-produced, it has a pH of 7.00000. Upon exposure to the atmosphere in my storage tank, carbon dioxide dissolves in it forming carbonic acid, which causes the pH to plummet to the upper 4's or low 5's. Folks freak out because they "know" that's just way too acidic for the plants. What they fail to realize is that carbonic acid is so weak that almost anything will overwhelm its effect on pH - a tiny amount of fertilizer is far stronger than the H2CO3.

Semi-hydroponics is just one form of hydroponics - in this case, single-pot hydro. The LECA potting medium plays essentially no role in nutrition or pH, so you need to manage that through the solutions you apply.

[krpot]

Ray, Thank you for the informative post. So, if I measure the pH after adding fert to the water that's been sitting out for a while to come to room temp that would be a more accurate reading? I don't know how much the bark mix would alter the pH. Woah, this is so complicated. Will read that article.