Foliar vs Root Fertilizing and other Fert Questions

[GreyThumb]

Hello everyone! I'm hoping you can help me out with some questions I have about fertilizing my orchids. I got my first orchid about 6 years ago. I really wasn't able to find any straight forward care information about orchids at the time. I'm sure there was some out there, it just wasn't something I found. The information I found then and what I find now still conflicts. There seem to be two opinions on the proper way to do something for every one person out there. That seems pretty standard with most things, though.

So I got my orchid and tried to cobble together some basic care instructions from what I could find. I shudder at some of the care tips I found back then, the same way I'll probably shudder in 10 years when I look back at the way I'm doing things now. At the time however, it came down to soaking my orchids pot in water once a week and fertilizing once a month or whenever I thought about it. It was a "Miltassia Shelob 'The Weed' " for anyone who was interested.

Of course I damaged it several times. It came to me in sad shape anyway. It was in rotten bark, in a pot, which was wrapped in plastic, with a rubber band around the base, and dropped the whole thing into a perforated plastic bag. This whole thing was allowed to hang on a shelf in a store for at least the 2 weeks that I walked by it, trying to make up my mind whether or not to shell out the $14-or-so out of my meager money, at the time. Who knows how long it had been bagged before that.

So I took it home and repotted it in straight orchid bark. I put it in a ceramic, glazed pot with a drain hole at the bottom. Orchid pot were impossible to find, where I live, at the time and I still don't see a lot of them. It took it 6 months to start showing any growth and 4 years to bloom. Of course this was with plain water and no fertilizer. Since it spiked the first time, it consistently grows a new bulb and spikes about 1-2 times a year. I tried to acclimate it to the shaded front porch once and burnt the crap out of it in the first day. I finally grew enough bulbs to cut off the damaged ones. It's just grown enough since then to divide it for the first time. I have two now.

It never occurred to me to fertilize it. I don't know why as I occasionally fertilize my regular house plants. I'd really like to start fertilizing it, along with my other orchids and start see better, more abundant, and faster growth.

This is where I'm stuck, though. There are so many options. From special orchid fertilizers, to standard fertilizers at a weaker concentration, to homemade brews. Then you have foliar feeding vs drenching vs pellets in the media. After scanning this site, I even see that certain orchids need less or more of certain elements, so you can't even have a basic fertilizer to use on all of them. That makes sense to me in hind site, but it wasn't something I'd thought about.

Currently, I have some 'Better-Grow Urea Free' fertilizer and bloom booster. I also have some Maxsea 16-16-16 that I just ordered -----------------------, some standard Miracle Grow Fertilizer, and an unopened bottle of Superthrive I picked up to try on some other plants.

I've been watching a good orchid channel -----and this guy said he does a foliar feed. He has a liquid seaweed fert. that he mixes in a pump up spray bottle. However, he tries to only spray at the base of the plant and doesn't spray much on the leaves. To me foliar has to do with foliage.

I recently bought a few orchids from a local hobby grower/dealer. He has a doctorate in something that applies to chemicals. I assume it has something to do with fertilizers. I asked him about care for the orchids I bought. He told me not to use bloom boosters. He said to just use a standard orchid fertilizer and mix it up in a spray bottle and spray the leaves/bulbs/etc... once every 2-3 weeks. He didn't say anything about getting it on the roots, minus the air roots of course.

I've seen another guy who mixes the fertilizer into the water and pours it directly onto the media and roots. However, he only does it after he's watered with straight water first. Supposedly so they won't overdose on the fertilizer. They'll absorb the straight water first and not have a lot of room left for the fert. water.

You can look at my grow list to see the majority of what I'm growing. I don't have my newest purchases on there yet, because I either don't have permission to edit my posts yet or I'm looking in the wrong place.

I'd just like to know what the best way to feed my orchids is; foliar spray or root feeding. Then I'd like to know which is the best out of the fertilizers I mentioned having above. Lastly, do any of my orchids stand out as needing a special fertilizer or more or less of the standard fertilizer.

I apologize for the info dump. I did search this site before posting. While I see a lot of fertilizer talk on this site, again, it's conflicting sometimes. I did see where one poster mentioned a study where they fertilized the tops of the leaves, the bottoms of the leaves, new roots, and old roots and found that you achieve best results by fertilizing the roots, specifically the young roots. The least effective was spraying the underside of the leaves. The looks to me like it would be best to fertilize the plants buy mixing water and fertilizer in a can and pouring it into the pots. The doctor who advised me to spray the leaves did have a thriving greenhouse, though.

I know this all depends on multiple variables, such as the individual plants, light, humidity, temp, etc... By the way, I'm growing most of them in my room with south and west facing windows, supplemented by a 6500k CFL and I water them with well water. I've only tested the water once with my new stick and found the water to have 115ppm in a glass of water I'd been drinking out of. (Being fair, there is a possibility of mild backwash).

I'd just like some help determining what my best course is to get robust orchids. I live in upper-SC and I'd like to be able to put some of my orchids out on a shaded front porch this summer. I think the warmth and humidity would do them good. As of right now and all winter for them, they'll be in the house till the glorious day I can settle on a plan and save the funds for a nice greenhouse. Thanks everyone.

GreyThumb

[Chris in Hamilton]

I've seen another guy who mixes the fertilizer into the water and pours it directly onto the media and roots. However, he only does it after he's watered with straight water first. Supposedly so they won't overdose on the fertilizer. They'll absorb the straight water first and not have a lot of room left for the fert. water.I've seen another guy who mixes the fertilizer into the water and pours it directly onto the media and roots. However, he only does it after he's watered with straight water first. Supposedly so they won't overdose on the fertilizer. They'll absorb the straight water first and not have a lot of room left for the fert. water.

This is about what I do. Working a shelf or two at a time I take them to the bathtub, run the shower for a minute or two so everything is a little wet, wait ten minutes then using a watering can, fertilize. Then I wait another ten minutes, carry those ones back and move on two next shelf. I do the wetting down thing because its really not a good idea to fertilize dry roots. It takes about 5 hours two or three times a week and is a total pain in the patootie. Lordy I need a greenhouse!!!

[raybark]

This can be a particularly complex subject, and there are more opinions than there are growers out there, but I believe that some scientific evaluation of plants' conditions in the wild can help simplify it. The following is my "take" on the subject, but keep in mind that everything (and I do mean everything) is not "black and white", but a matter of degree:

Foliar versus Root Feeding:

• Because many orchids have evolved to be very conservative with their water, they have developed thick, waxy, cuticle layers on their leaves to retard water loss. It's particularly evident in phalaenopsis, for example. Those layers tend to be very water repellent, so would prevent the rapid absorption of the aqueous solutions.
• The areas of the leaf surface that DO absorb are closely associated with stomata (which don't absorb liquids), but again, as a water conservation adaptation, they tend to be on the undersides of leaves, which tend to see less solution exposure.
• Orchids vary all over the map, so some plants may absorb better than others.

Water First, Then Feed:

• In nature, epiphytes attached to trees and shrubs basically only get fed only when it rains, and the exudates and collected detritus gets washed down to them out of the canopy.
• That happen almost immediately upon the commencement of rain, then it's nothing but pure water after that. The velamen on the roots has been shown to be particularly good at trapping the nutrient ions immediately, and holding onto them, so they won't be washed away by the continuing downpour - another evolutionary adaptation for their "niche" lives.
• If you water first, you saturate the velamen, and the plant can no longer absorb the nutrients from the later-applied solutions as well.

Urea versus Non-Urea Nitrogen Sources: There is a lot of discussion as to whether urea may be directly absorbed by orchid plants, and the "common knowledge" is that it must be decomposed into ammonium compounds for absorption, but that's not strictly true.

• Nitrates and ammonium compounds are poorly absorbed through the leaves, but are preferentially absorbed through the roots.
• Urea has just the opposite affinity, which is why many "Green Up" products sold for lawns are loaded with urea.

Formula & Concentration:

• Orchids are about 85% water, 14% carbon and nitrogen, and 1% everything else, combined.
• Analyses of the "throughfall" and "trunk flow" of water cascading from the leaf canopy and down branched to epiphytes has been shown to be <25 ppm total dissolved solids (TDS), with almost all of that being nitrogen.
• There is no such thing as a "bloom booster". A plant is genetically programmed to bloom to its maximum potential, and a well-grown plant will do so. The best we can try to attain is to not do something that detracts from that.
• Rotating fertilizer formulas - unless you have poor ones - is a waste of time. That plant in nature sees a nearly identical "diet" at every feeding for its entire life.

So summing all of that up, I have adopted the following regimen:

• Use a high-nitrogen fertilizer formula. I like K-Lite (12-1-1-10 Ca-3 Mg)
• Make sure the formula is complete, with all of the trace elements.
• Apply it at a very low concentration (I use 25 ppm N) at every watering.
• Select a potting medium and container that allows frequent watering without suffocating the roots.
• Flood the pot at each watering. Not only is it irrigation and feeding, but it aerates the pot and flushes away fertilizer residues and plant waste products.

I have been growing orchids for over 40 years, and my regimen evolved to that about 5-6 years ago, and I have never seen my plants do better.

[JDT]

Ray posted some good information. Personally I never water my orchids first before fertilizing for the exact reason Ray gave, if you do that you are pretty much pouring your fertilizer down the drain. I use a irrigation system on my orchids and they all get watered, if you are ever at a nursery when they water all the plants get watered leaves and all, but with only a few orchids I would only water the roots as I have killed many a new growth by getting water into the top of that new growth which eventually dies off unless you remove the water from the top crown. I am sure that those who put theirs into the bathtub and turn the shower on them will check the top of those crowns when they move them back to the spot they keep them in. During the growing season I fertilize once a week then during their down time of growth I will fertilize every 2 weeks those that do not require a winter rest. I use a time release fertilizer plus I use organic products for fertilizer.

You need to decide which technique works best for you, it is a hit and miss process but once you come up with your best method you stick with it.

[sciencegal]

I adopted Ray's protocol because it makes sense - biologically speaking - and I see the orchids looking better and happier, and I am getting blooms. I think that the roots get fertilizer burn when the salts build up in the media, not because there is fertilizer in the water, or if high concentrate fertilizer is poured on the roots then allowed to dry without being flushed off with lots of water. I use plain water about once out of every three or four waterings or actually soakings which is how I water, sometimes just because I am in a hurry and do not want to take the time to make up the fertilizer.

I have been using K-lite at 25 ppm N on African violets on a wicking system with a plain water flush once in a while. They grow and bloom really well. That tells me they do not need the high P bloom booster that some recommend.

[raybark]

Another thing to consider is the importance of watering, as that is well above feeding in the plants' "Maslow's heirarchy" of needs.

Growth of a plant is more about fixing carbon than anything else. That primarily comes from CO₂ in the air, but watering affects that capture.

There is an enzyme within plants that can react either with oxygen or carbon dioxide. When the water supply is readily available, hormones send signals upward telling the leaf stomata to open, which allows the "inhaling" of more fresh air, containing roughly 4% CO₂ at this point, and the "exhaling" of the O₂ freed during carbon fixing. If the water supply is lacking, as happens when we water infrequently, those hormone signals are not sent, the stomata stay closed, and the CO₂/O₂ ratio decreases, lessening the probability of that enzyme to fix nitrogen, hence slowing growth.

If one does the calculations associated with carbon fixing, in order for a plant to gain 1 kilogram of mass, it must process roughly 210 liters of water, and only 10 grams of fertilizer elements.

[Chris in Hamilton]

Dang! Now I have to change the plan again!

[sciencegal]

Then there is the symbionic relationship between orchids and fungi to take into account.

The authors found that all four orchids had higher N15 compared to their neighbors, indicating that these orchids do depend on their fungal symbionts for a substantial amount of nutrition. Moreover, the orchid with the highest fungal specificity, Orchis purpurea had the highest N15 and C13 gain, and was thus partly dependant on its fungal partners for organic carbon.

[KC Kam]

Hi All,

I have something that I need you all to help to clarify abit. Previously I've been using 21-21-21 fertilizer with 1/4 strength dilute in water and water directly. Everything seems fine for few months.

Until recently I got a new fertilizer known as orchid booster. I also use 1/4 strength and after 3-6 application over the span of 2 weeks some of my orchid root tips turn brown. I stop fertilizing and has been flushing with plain water for 2 days nw. It happen mostly on hanging root tips and those that dry up slower due to recent cooling days in my area where water evaporate slower.

I have a friend that uses the same fertilizer but he fertilize almost 1/3 of the strength yet nothing happen to his orchids. He did mentioned his place has strong wind and he only fertilize once a week. I believe his environment is more windy, that why he does not have such problem? Does the orchid really absorb more fert compare to mine 1/4 strength?

I saw this post where sciencegal mentioned that over fertilize is due to the media? If this is the case does it mean that after flushing I should continue with 1/4 strength? or reduce the strength furthermore? When should I continue fertilizing?

Pls advice..
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[ksriramkumar]

Well...one important difference between your friend (1/3rd strength) and yours (1/4) is quality of water and pH of the media+fertilizer solution. Check the overall TDS of fertilizer solution of yours and your friend and can decide based on that.