Clippings by vanman23

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RE: greenhouse heating with hot water tubing (Follow-Up #20)

posted by: sunworksco on 08.20.2008 at 11:11 am in Greenhouses & Garden Structures Forum

The best way to heat your plant beds with warm water is to use 3/8" PEX pipe connected to a Noritz gas/lp instantaneous tankless water heater,circulate the water with a Taco pump using a Goldline thermostat control.Install the thermostat sensor in the plant bed soil.Make sure that the bottom of the beds are insulated with styrofoam and the top of the beds have sawdust or small wood chips.You can build yourself a passive water heater out of a couple of 50 gallon water heater tanks.Remove the tank shells and insulation from electric water heaters and install inside a concrete coffin crypt all painted with chassis black.The crypts can be mounted in the ground facing true south with the crypts tilted on angle to your geographical degree of latitude for the best solar exposure through the year.These passive solar heaters can preheat the Noritz heater.It is also very energy savings to build the greenhouse below the ground level for added thermal mass and insulation.

Here is a link that might be useful: INDEKSOLAR POOL HEATING


clipped on: 09.23.2014 at 08:49 am    last updated on: 09.23.2014 at 08:49 am

RE: Interior GH wall covering (Follow-Up #2)

posted by: birdwidow on 05.02.2009 at 06:47 am in Greenhouses & Garden Structures Forum

What about exterior MDF siding? It's rigid enough to be used with no backing, comes pre-primed, and a 4 x 8 ft. panel is usually priced under $25.00, give or take, and unlike OSB; has a smooth and easy to paint surface. We used it on our large garden shed 20 years ago and it's still solid. Of course it's been repainted several times since, but it's also exposed to the worst weather the Midwest can throw at it.

It would also allow you to drill into it to mount shelving, or hooks to hold tools, etc., and if/when you decide to change things about, the holes can be filled in and painted over.

The important thing is to seal it completely at all seams with a high quality, paintable, exterior grade caulk, and use only galvanized, exterior grade fasteners to mount it.

I found the Olympic acrylic soild stain to work best on it. It covers exceptionally well and dries to a soft, satin sheen, although for a solid, streak free finish, would likely require 2 coats for the initial application.


clipped on: 09.22.2014 at 08:51 am    last updated on: 09.22.2014 at 08:51 am

RE: help with misting/prop timer trouble (Follow-Up #3)

posted by: hex2006 on 07.15.2009 at 08:15 pm in Greenhouses & Garden Structures Forum

I guess it depends on the mist heads you have, i use netafim coolnet foggers and they have small ADV`s inline to each head, its an egg shaped unit with a spring inside that pushes on the internal tube.
They come in different pressure ratings, the ones i have open at 58psi and close at 26psi.
When the solenoid opens it pressurizes the line from ~26psi to 58psi at which point the heads instantly fire up (no ramping of the spray). When the solenoid closes, the line pressure drops to 26psi and the ADV automatically shuts off the drips.
With currency conversion the adv`s wouldnt cost more than $1 each. A 4 way cross head assembly,adv and hanger would probably be around $6. Good for a 5ft circle coverage
Cold water inlet solenoid valves from washing machines are very reliable (and sometimes cost nothing), they run on mains voltage though so you`d need to mount them indoors out of the weather for safety.
To run one with your timer you`d need probably need to use a 24v coil relay with mains rated contacts. Mine runs quite happily with cycle times of 1 second on/60 seconds off although i generally use 3 seconds on/3 minutes off to give the solenoid an easy life.

If you have broadband i`d recommend taking a look at the greenhouse misting video on the netafim website, its a 15MB wmv but shows you exactly what they do.


clipped on: 09.21.2014 at 11:47 am    last updated on: 09.21.2014 at 11:47 am

RE: Greenhouse Questions for beginner (Follow-Up #3)

posted by: bcfromfl on 07.02.2008 at 11:31 am in Greenhouses & Garden Structures Forum

If you're well-capitalized, the link below is to an article about a guy who has done what you suggest in a cool climate.

-Bruce C.

Here is a link that might be useful: Joseph Orr's solar greenhouse


clipped on: 09.21.2014 at 01:25 am    last updated on: 09.21.2014 at 01:25 am

RE: Best Material to Weatherproof Wood (Follow-Up #3)

posted by: birdwidow on 05.01.2009 at 09:59 am in Greenhouses & Garden Structures Forum

Exterior grade penetrating oil stain wins, hands down. It will penetrate into the pores of the wood and when the resins in it dry, actually hardens the wood and while it may surface fade in time, it won't chip off.

With raw, untreated wood, lay on at least 3 coats. The first one will dry almost immediately, as the wood will literally suck it in.

Each sucessive coat with take a bit longer to dry, so keep coating until the stain seems to lay on the surface. Then, have some patience. Let it sit in a dry place until cured, at least 3 days- and the surface will have a soft sheen.

In fact, if you give it a very light sanding with a fine pad after each coat, then wipe it with a tack cloth before the next and repeat for each coat, you will end up with a satin smooth finish that will clean easily and look a lot nicer than most work benches. Mainly, it will last far longer while it pleases your eye. As a final finish on the top, lay on a coat of paste wax, buff it out, and you will be able to treat it as if it were formica.

Semi-transparent stain is best as it contains more oil than pigment as opposed to solid color stain and given enough coats, will end up with a pretty even color anyway, and if a wee bit of graining still shows through; would that be an issue for you?


clipped on: 09.11.2014 at 07:46 am    last updated on: 09.11.2014 at 07:46 am

RE: Greenhouse plumbing (Follow-Up #3)

posted by: fuzzymoto on 04.26.2010 at 11:01 am in Greenhouses & Garden Structures Forum

You can split hose outlets as many ways as you like, but we decided to start with 4 dedicated water outlets. One for misting, one for drip irrigation, one for a hose and an open one we use for a 2nd hose on the other side of the GH to prevent knocking over pants when we water.


clipped on: 09.11.2014 at 12:06 am    last updated on: 09.11.2014 at 12:06 am

RE: Soil Drench (Follow-Up #1)

posted by: bluebonsai101 on 10.02.2010 at 09:54 pm in Greenhouses & Garden Structures Forum

While I do not have a GH I do put a couple hundred plants under MH lights for the winter. I use two Bayer products before I bring them in for the winter. I use Bayer Tree and Shrub (or something like that) that has imidacloprid in it....the one I can buy is 1.47% and I use 2 TBSP/Gal for a soil drench and a leaf spray. This is great for bugs like Mealies, etc. I use this on all my plants which include various Amaryllids from South America and South Africa as well as my various caudiciforms. I also use the 3 in 1 product from bayer that not only has imidacloprid as well as other things like a miticide and a fungicide. I can only find this as a spray so it wastes a ton. By doing this I never have any bugs or mites over the winter. Best of luck :o) Dan


clipped on: 09.10.2014 at 07:27 am    last updated on: 09.10.2014 at 07:27 am

RE: Greenhouse base - novice needs help (Follow-Up #10)

posted by: birdwidow on 03.21.2007 at 03:10 pm in Greenhouses & Garden Structures Forum

Maryanne and Turquoise:

Again: everything depends on intended use. In any climate subjected to sub-freezing temps, let alone sub-zero, if a GH is to be heated and used year round, ground insulation is vital, presuming you don't want to spend more to heat the GH than you do your home.

But for only seasonal use, and it's not fall season extention that's the challenge, as by the time the leaves are falling after a hot midwestern summer, the ground inside a GH is nice and toasty and will stay warm for quite a while, even after after the first frost. It's bringing it back up after months of hard freeze, when you would presumably want to jump start seeding plants.

If I were planning only seasonal use and had no drains, I would still use foam insulating panels, but limit them to the perimiter and rent a Ditchwitch, to cut a deep, narrow trench all around the GH base and set them in upright.

Also, I would install a drywell into the center of the GH, as a simple yet effective way to get rid of excess water, especially when the surface of the ground outside of the GH is still either frozen, or already saturated from spring thaws.

For that, either rent a post hole digger with the largest auger, or get onto the working end of an idiot stick and start digging. To line a drywell, just cut out the bottom of a very large, tall plastic garbage can, set it into the hole, fill it with rocks- 4-6" road base stone is good, then lay a piece of heavy vinyl or aluminum screening over it, to prevent small stones and dirt from draining into it and eventually cloging the spaces beteween the rocks. That also allows the use of small stone for the GH floor, such as pea gravel. The screening will prevent the pea gravel from falling into the drywell.

It also means a bit of grading inside of the GH foundation, but not much; just enough to aim excess water to the center. Then, lay heavy weed blocker fabric over floor, level with the top of the drywell, check the slope with a garden hose, and when it's all where you want it, fill in the entire space with small gravel. Road mix is easy to rake, and will pack down to a nice firm surface, but I prefer pea gravel myself. It's costlier, but also drains a lot better and is comfortable to walk on.

Either way; no weeds or puddles. You can then use patio blocks or brick for your walking paths if you want, or just lay more fabric down, to prevent disturbing the small gravel.

But for any drywell to be effective in cold country, it must be below frost line at the bottom. The deeper the better. If it's necessary to extend the length of the garbage can, just use two. Cut the bottoms out of both, then set the top one into into the bottom can to the desired height and run in a few bolts to hold them together. Once it's all in the ground and the outside has been packed in well and the center filled with rocks, it won't move or separate.

Also: I admit that I keep harping on it, and maybe it's just me, but I will NOT have mice in my GH... If you lay 2 ft wide, 1/2" mesh hardware cloth just under your timber base and out, then secure it down, no mouse will ever burrow under the base and into your GH.


clipped on: 09.10.2014 at 07:25 am    last updated on: 09.10.2014 at 07:25 am

RE: Greenhouse floor insulation (Follow-Up #7)

posted by: stressbaby on 11.08.2010 at 09:59 pm in Greenhouses & Garden Structures Forum

It depends upon the size of your greenhouse.
In university studies, about 2-3% of heat is lost through the perimeter. Here is a link: However, I believe that these studies are done on larger greenhouses or greenhouses in warmer climates or both.

I did some calculations using a smaller greenhouse in a colder climate here: I came to the conclusion that a 6x8 GH could loose up to 13% of its heat through the perimeter. That is significant and it would make sense to insulate the perimeter in some way.

You must distinguish perimeter loss from loss through the ground. Losses through the ground are essentially zero, which may not be intuitive, but is discussed in detail in one or more of the three links I've included.

Here is a link that might be useful: Another discussion


clipped on: 09.09.2014 at 03:58 am    last updated on: 09.09.2014 at 03:58 am

RE: Strawberries (Follow-Up #2)

posted by: web4deb on 11.09.2010 at 08:47 pm in Greenhouses & Garden Structures Forum

I grow strawberries in my greenhouse. You can look through my videos at and also my blog at There's some details about them that should be helpful.


clipped on: 09.09.2014 at 03:55 am    last updated on: 09.09.2014 at 03:55 am

RE: stawberry growing vertically in greenhouse (Follow-Up #1)

posted by: web4deb on 02.04.2011 at 02:10 pm in Greenhouses & Garden Structures Forum

Just about any type will grow good. Personally, I don't like the everbearing type. I like to get all my berries at once and freeze or process larger groups.

Here's a little video I put together about my verical growing:

Here is a link that might be useful: Build your own strawberry tower


clipped on: 09.09.2014 at 03:41 am    last updated on: 09.09.2014 at 03:41 am

RE: Greenhouses in China (Follow-Up #1)

posted by: jrslick on 03.09.2011 at 03:53 pm in Greenhouses & Garden Structures Forum

That is just simply amazing! They seem so simply built. I learned about these types of structures several years ago, I wish I could find a location to build one.


Here is a link that might be useful: More Chinese Greenhouses


clipped on: 09.09.2014 at 03:38 am    last updated on: 09.09.2014 at 03:38 am

Coaxing fruit from the lychee in the north

posted by: stressbaby on 04.17.2011 at 10:26 am in Tropical Fruits Forum

Hey all,

I have a couple of lychees in my GH, Sweetheart and Brewster. I have struggled in a couple of ways to coax fruit from these babies, but finally this year I think I've learned enough to get a little consistency. I thought I'd post this year's experience for some feedback.

First, it has tough to get consistent blooms and to get them at the right time. Too often, the growth flushes were ill-timed, and either they were too late (it was into June and too hot) or non-existent. This year looked like another poorly timed year. So I went with some advice from Lychees Online and pruned that new growth back. Twice. Hard. Sure enough, lateral buds flushed bloom spikes. This revelation has me optimistic for consistent flushes each year going forward.

But the bigger struggle has been pollination. NTM has more patience with his brush than I do apparently. My problems have been 1) speed and 2) identifying and collection good pollen. Over the years I've tried many methods, and most had some issue. Brushing pollen directly from males and onto females (brush gets sticky, slow, but it works); making a pollen slurry with water, brushing that on females (faster but poor pollination rates); making solution and spraying on the blooms (fast but poor pollination rates); picking off individual males, testing for pollen, and brushing those flowers by hand, one at a time, directly on the females with tweezers (painfully slow, and poor pollination rates, believe it or not).

Finally 2/3 of the way through this year's bloom cycle, I think I found a way that is fast and effective. What I did was to tap the spikes with male flowers over a piece of black plastic (actually a Folgers plastic coffee can lid). The flowers fall onto the lid and I could immediately see if there was the yellowish dusting on the lid that signalled good pollen. Then I dragged a small paintbrush across the surface to pick up the pollen. With a nice yellow dusting on the tip of the brush, I just touched each flower. This seems to have given me much better pollination rates so far, results in the brush getting sticky much less often, and is pretty fast, too.

Thoughts? If and when this crop gets big enough to be sure the fruit will make it to maturity, I'll post some pics.

You guys in the south don't know how lucky you are.


clipped on: 06.03.2014 at 02:55 pm    last updated on: 09.09.2014 at 03:35 am

RE: A few pics of my Emperor lychees (Follow-Up #41)

posted by: bloobeari on 05.17.2014 at 03:02 pm in Tropical Fruits Forum

Hi grandy3,

You might want to research "anthracnose" and "downy mildew" in lychee trees. You leaves look like it could be either and it would definitely affect the flowers and then the fruit. A product I have had great success with for both these conditions, plus it's organic, is Organocide Plant Doctor. They sell it at Home Depot so it's easy to find. The regular Organocide 3-in-1spray would also help. I spray it on all my citrus trees and it works great. Hope this helps. I have an Emperor as well.


clipped on: 05.31.2014 at 10:36 am    last updated on: 05.31.2014 at 10:36 am

RE: Gritty Mix + Citrus Plants + Foilage Pro - Questions (Follow-Up #20)

posted by: tapla on 02.20.2011 at 12:20 pm in Container Gardening Forum

Redshirt - you must have misunderstood about the Ca:Mg ratio of FP 9-3-6. It is perfect insofar as the Ca:Mg ratio goes, AND it is also perfect relative to the % of N supplied. The most important considerations for fertilizer from the plant's perspective is what is available and when, and how much of each nutrient is present in relation to other nutrients. I can see there was a lot of thought that went into developing the fertilizer because the 3:1:2 ratio is about as close as you can get to what plants actually use (a decided advantage when it comes to our trying to keep EC/TDS levels low and still not have our plants suffering deficiencies), and because all 12 nutrients plants take from the soil are present in a favorable ratio to each other.

The rule of thumb: Use dolomitic (garden) lime in the 5:1:1 soil except under unique & specific circumstances that are prolly not worth mentioning now. For the gritty mix, use gypsum as a Ca source IF your fertilizer does not contain Ca. Most soluble fertilizers do not, because they use urea as their N source. Ca nitrate is the only suitable soluble source of Ca and it is much more expensive than urea. Plus, most container soils are pH adjusted with dolomitic lime, which acts as a Ca source. The gritty mix would be too high in pH to be optimal if we added lime, so we limit the Ca source to something that is pH neutral - gypsum. Foliage pro does have Ca, and all the plants I've grown so far show no signs of Ca deficiencies if I use 9-3-6 and leave the gypsum out, but you DO need it if you're using MG, Schultz, Peter's ...

IF you use gypsum and your fertilizer does NOT have Mg, you need to supplement the Mg by adding Epsom salts each time you fertilize. Do this by including 1/8 - 1/4 tsp of Epsom salts per gallon of water each time you fertilize.

FP sometimes shows a tendency for the Ca to precipitate out of solution at times - especially when it gets cold. Warming the fertilizer before using it, and diluting it 1:1 with water before using it in your injector system will ensure the Ca stays in solution. It will also ensure the added MgSO4 (Epsom salts) you add to your fertilizer solution will dissolve properly and not cause additional Ca to precipitate out of solution.

I really need to get an injector system to both acidify my irrigation water (mine comes in at a pH of about 8.5-8.8) and to speed the fertilizing process. I actually fertilize 300+ containers in the summer by hand (2-1/2 gallon watering can) on pretty much a weekly basis. It's a drag ..... but a good thing I love being outdoors. I could probably spend the 3+ hours it takes to fertilize every weekend doing something not so tedious. Note: I could easily take the easier road & fertilize at a higher, instead of at a reduced rate, & extend the interval to 2 weeks instead of weekly, but the plants keep telling me they like the more frequent low doses (especially when it's rather hot or quite cool), so .....



clipped on: 02.06.2014 at 09:59 am    last updated on: 02.06.2014 at 09:59 am

RE: Grape propagation? (Follow-Up #12)

posted by: capt44 on 07.14.2009 at 02:06 am in Plant Propagation Forum

To propagate muscadines, take several cuttings with at least 3 leaf nodes.
Bundle them together, all in the same direction.
Dig a hole and place the bundle in the hole upside down.
cover with soil and mark the location.
Next spring dig up the cuttings and they will be calloused.
Place the calloused cuttings, callous down in a bed of damp sand in a shaded area.
The callouse is where the roots will form in a few days.
It is a pretty good way to root muscadines.


clipped on: 01.23.2014 at 10:56 am    last updated on: 01.23.2014 at 10:56 am

Fertilizering Containerized Plants IV

posted by: tapla on 04.06.2012 at 04:30 pm in Container Gardening Forum

This topic has proven to be a fairly popular addition to the Container Gardening forum, having reached the maximum number of posts allowed on three previous occasions, so I'll post it for its fourth go-round. Nutrient supplementation has been discussed frequently, but usually in piecemeal fashion, on this forum and forums related. Prompted originally by a question about fertilizers in another thread, I decided to collect a few thoughts & present an overview that will hopefully be seen as a simplification and found to be helpful.

Fertilizing Containerized Plants IV

Let me begin with a brief and hopefully not too technical explanation of how plants absorb water from the soil and how they obtain the nutrients/solutes that are dissolved in that water. Most of us remember from our biology classes that cells have membranes that are semi-permeable. That is, they allow some things to pass through the walls, like water and select elements in ionic form dissolved in the water, while excluding other materials like large organic molecules. Osmosis is a natural phenomenon that is nature's attempt at creating a balance (isotonicity) in the concentration of solutes in water inside and outside of cells. Water and ionic solutes will pass in and out of cell walls until an equilibrium is reached and the level of solutes in the water surrounding the cell is the same as the level of solutes in the cell.

This process begins when the finest roots absorb water molecule by molecule at the cellular level from colloidal surfaces and water vapor in soil gasses, along with the nutrient load dissolved in that water, and distribute water and nutrients throughout the plant. I want to keep this simple, so I'll just say that the best water absorption occurs when the level of solutes in soil water is lowest, and in the presence of good amounts of oxygen (this is where I get to plug a well-aerated and free-draining soil). Deionized (distilled) water contains no solutes, and is easiest for plants to absorb. Of course, since distilled water contains no nutrients, using it alone practically guarantees deficiencies of multiple nutrients as the plant is shorted the building materials (nutrients) it needs to manufacture food, keep its systems orderly, and keep its metabolism running smoothly.

We already learned that if the dissolved solutes in soil water are low, the plant may be well-hydrated, but starving; however, if they are too high, the plant may have a large store of nutrients in the soil but because of osmotic interference the plant may be unable to absorb the water and could die of thirst in a sea of plenty. When this condition occurs, and is severe enough (high concentrations of solutes in soil water), it causes fertilizer burn (plasmolysis), a condition seen when plasma is torn from cell walls as the water inside the cell exits to maintain solute equilibrium with the water surrounding the cell.

Our job, because we cannot depend on an adequate supply of nutrients being supplied by the organic component of a container soil as it breaks down, is to provide a solution of dissolved nutrients in a concentration high enough that the supply remains in the adequate to luxury range, yet still low enough that it remains easy for the plant to take up enough water to be well-hydrated and free of drought stress. Electrical conductivity (EC) of, and the level of TDS (total dissolved solids) in the soil solution is a reliable way to judge the adequacy of solute concentrations and the plant's ability to take up water. There are meters that measure these concentrations, and for most plants the ideal range of conductivity is from 1.5 - 3.5 mS, with some, like tomatoes, being as high as 4.5 mS. This is more technical than I wanted to be, but I added it in case someone wanted to search 'mS' or 'TDS' or 'EC'. Most of us, including me, will have to be satisfied with simply guessing at concentrations, but understanding how plants take up water and fertilizer, as well as the effects of solute concentrations in soil water is an important piece of the fertilizing puzzle.

Now, some disconcerting news - you have listened to all this talk about nutrient concentrations, but what do we supply, when, and how do we supply them? We have to decide what nutrients are appropriate to add to our supplementation program, but how? Most of us are just hobby growers and cannot do tissue analysis to determine what is lacking. We CAN be observant tough, and learn the symptoms of various nutrient deficiencies - and we CAN make some surprising generalizations.

What if I said that the nutritional needs of all plants is basically the same and that one fertilizer could suit almost all the plants we grow in containers - that by increasing/decreasing the dosage as we water, we could even manipulate plants to bloom and fruit more abundantly? It's really quite logical, so please let me explain.

Tissue analysis of plants will nearly always show NPK %s to be very close to an average ratio of approximately 10:1.5:7. If we assign N the constant of 100, P and K will range from 13-19 and 45-70 respectively. (I'll try to remember to make a chart showing the relative ratios of all the other essential nutrients plants normally take from the soil at the end of what I write.) All we need to do is supply nutrients in approximately the same ratio as plants use them, and at concentrations sufficient to keep them in the adequate to luxury range at all times.

Remember that we can maximize water uptake by keeping the concentrations of solutes low, so a continual supply of a weak solution is best. Nutrients don't often just suddenly appear in large quantities in nature, so the low and continual dose method most closely mimics the nutritional supply Mother Nature offers. If you decide to adopt a "fertilize every time you water" approach, most liquid fertilizers can be applied at 3/4 to 1 tsp per gallon for best results. If you decide that is too much work, try halving the dose recommended & cutting the interval in half. You can work out the math for granular soluble fertilizers and apply at a similar rate.

The system is rather self regulating if fertilizer is applied in low concentrations each time you water, even with houseplants in winter. As the plant's growth slows, so does its need for both water and nutrients. Larger plants and plants that are growing robustly will need more water and nutrients, so linking nutrient supply to the water supply is a win/win situation all around.

Another advantage to supplying a continual low concentration of fertilizer is, it eliminates the tendency of plants to show symptoms of nutrient deficiencies after they have received high doses of fertilizer and then been allowed to return to a more favorable level of soil solute concentrations. Even at perfectly acceptable concentrations of nutrients in the soil, plants previously exposed to high concentrations of nutrients readily display deficiency symptoms, even at normal nutrient loads.

You will still need to guard against watering in sips, and that habit's accompanying tendency to ensure solute (salt) accumulation in soils. Remember that as salts accumulate, both water and nutrient uptake is made more difficult and finally impaired or made impossible in severe cases. Your soils should always allow you to water so that at least 10-15% of the total volume of water applied passes through the soil and out the drain hole to be discarded. This flushes the soil and carries accumulating solutes out the drain hole.

I use a liquid fertilizer with a full compliment of nutrients and micronutrients in a 3:1:2 ratio. Note that 'RATIO' is different than NPK %s. Also note how closely the 3:1:2 ratio fits the average ratio of NPK content in plant tissues, noted above (10:1.5:7). If the P looks a little high at 4, consider that in container soils, P begins to be more tightly held as pH goes from 6.5 to below 6.0, which is on the high side of most container soil's pH, so the manufacturer probably gave this some careful consideration. Also, P and K percentages shown on fertilizer packages are not the actual amount of P or K in the blend. The percentage of P on the package is the percentage of P2O5 (phosphorous pentoxide) and you need to multiply the percentage shown by .43 to get the actual amount of P in the fertilizer. Similarly, the K level percentage shown is actually the level of K2O ( potassium oxide) and must be multiplied by .83 to arrive at the actual amount of K supplied.

To answer the inevitable questions about specialty fertilizers and "special" plant nutritional requirements, let me repeat that plants need nutrients in roughly the same ratio. 'RATIO' is also an entirely a separate consideration from dosage. You'll need to adjust the dosage to fit the plant and perhaps strike a happy medium in containers that have a diversity of material.

If nutrient availability is unbalanced - if plants are getting more than they need of certain nutrients, but less than they need of others, the nutrient they need the most will be the one that limits growth. There are 6 factors that affect plant growth, vitality and yield; they are: air, water, light, temperature, soil or media and nutrients. Liebig's Law of Limiting Factors states the most deficient factor limits plant growth, and increasing the supply of non-limiting factors will not increase plant growth. Only by increasing most deficient nutrient will the plant growth increase. There is also an optimum combination/ratio of nutrients, and increasing them, individually or in various combinations can lead to toxicities and be as limiting as deficiencies.

When individual nutrients are available in excess, it not only unnecessarily contributes to the total volume of solutes in the soil solution, which makes it more difficult for the plant to absorb water and nutrients, it can also create an antagonistic deficiency of other nutrients as toxicity levels block a plant's ability to take them up. E.g., too much Fe (iron) can cause a Mn (manganese) deficiency, with the converse also true, Too much Ca (calcium) can cause a Mg (magnesium) deficiency. Too much P (phosphorous) can cause an insoluble precipitate with Fe and make Fe unavailable. It also interferes with the uptake of several other micro-nutrients. You can see why it is advantageous to supply nutrients in as close to the same ratio in which plants use them and at levels not so high that they interfere with water uptake. I know I'm repeating myself here, but this is an important point.

What about the high-P "Bloom Booster" fertilizers you might ask? To induce more prolific flowering, a reduced N supply will have more and better effect than the high P bloom formulas. When N is reduced, it slows vegetative growth without reducing photosynthesis. Since vegetative growth is limited by a lack of N, and the photosynthetic machinery continues to turn out food, it leaves an expendable surplus for the plant to spend on flowers and fruit. Plants use about 6 times more N than P, so fertilizers that supply more P than N are wasteful and more likely to inhibit blooms (remember that too much P inhibits uptake of Fe and many micro-nutrients - it raises pH unnecessarily as well, which could also be problematic). Popular "bloom-booster" fertilizers like 10-52-10 actually supply about 32x more P than your plant could ever use (in relationship to how much N it uses) and has the potential to wreak all kinds of havoc with your plants.

In a recent conversation with the CEO of Dyna-Gro, he confirmed my long held belief that circumstances would have to be very highly unusual for it to be ever beneficial to use a fertilizer in containers that supplies as much or more P than either N or K. This means that even commonly found 1:1:1 ratios like 20-20-20 or 14-14-14 supply more P than is necessary for best results.

The fact that different species of plants grow in different types of soil where they are naturally found, does not mean that one needs more of a certain nutrient than the other. It just means that the plants have developed strategies to adapt to certain conditions, like excesses and deficiencies of particular nutrients.

Plants that "love" acid soils, e.g., have simply developed strategies to cope with those soils. Their calcium needs are still the same as any other plant and no different from the nutrient requirements of plants that thrive in alkaline soils. The problem for acid-loving plants is that they are unable to adequately limit their calcium uptake, and will absorb too much of it when available, resulting in cellular pH-values that are too high. Some acid-loving plants also have difficulties absorbing Fe, Mn, Cu, or Zn, which is more tightly held in alkaline soils, another reason why they thrive in low pH (acid) soils.

So, If you select a fertilizer that is close in ratio to the concentration of major elements in plant tissues, you are going to be in good shape. Whether the fertilizer is furnished in chemical or organic form matters not a whit to the plant. Ions are ions, but there is one major consideration. Chemical fertilizers are available for immediate uptake while organic fertilizers must be acted on by passing through the gut of micro-organisms to break them down into usable elemental form. Since microorganism populations are affected by cultural conditions like moisture/air levels in the soil, soil pH, fertility levels, temperature, etc., they tend to follow a boom/bust cycle that has an impact on the reliability and timing of delivery of nutrients supplied in organic form, in container culture. Nutrients locked in hydrocarbon chains cannot be relied upon to be available when the plant needs them. This is a particular issue with the immobile nutrients that must be present in the nutrient stream at all times for the plant to grow normally.

What is my approach? I have been very happy with Foliage-Pro 9-3-6 liquid fertilizer. It has all the essential elements in a favorable ratio, and even includes Ca and Mg, which is unusual in soluble fertilizers. Miracle-Gro granular all-purpose fertilizer in 24-8-16 or liquid 12-4-8 are both close seconds and completely soluble, though they do lack Ca and Mg, which you can supply by incorporating lime or by including gypsum and Epsom salts in your fertilizer supplementation program. Ask if you need clarification on this point.

I often incorporate a granular micro-nutrient supplement in my soils when I make them (Micromax) or use a soluble micro-nutrient blend (STEM). I would encourage you to make sure your plants are getting all the micro-nutrients. More readily available than the supplements I use is Earth Juice's 'Microblast'.

When plants are growing robustly, I try to fertilize my plants weakly (pun intended) with a half recommended dose of the concentrate at half the suggested intervals. When plants are growing slowly, I still fertilize often, but with considerably reduced doses. It is important to realize your soil must drain freely and you must water so a fair amount of water drains from your container each time you water to fertilize this way. Last year, my display containers performed better than they ever have in years past & they were still all looking amazingly attractive at the beginning of Oct when I finally decided to dismantle them because of imminent cold weather. I attribute results primarily to a good soil and a healthy nutrient supplementation program.

What would I recommend to someone who asked what to use as an all-purpose fertilizer for nearly all their container plantings? If you can find it, a 3:1:2 ratio soluble liquid fertilizer (24-8-16, 12-4-8, 9-3-6 are all 3:1:2 ratio fertilizers) that contains all the minor elements would great.

How plants use nutrients - the chart I promised:

I gave Nitrogen, because it is the largest nutrient component, the value of 100. Other nutrients are listed as a weight percentage of N.
N 100
P 13-19 (16) 1/6
K 45-80 (62) 3/5
S 6-9 (8) 1/12
Mg 5-15 (10) 1/10
Ca 5-15 (10) 1/10
Fe 0.7
Mn 0.4
B(oron) 0.2
Zn 0.06
Cu 0.03
Cl 0.03
M(olybden) 0.003
To read the chart: P - plants use 13-19 parts of P or an average of about 16 parts for every 100 parts of N, or 6 times more N than P. Plants use about 45-80 parts of K or an average of about 62 parts for every 100 parts of N, or about 3/5 as much K as N, and so on.

If you're still with me - thanks for reading. It makes me feel like the effort was worth it. Let me know what you think - please.

Here is a link to the previous posting of A Fertilizer Program for Containerized Plants, in case you'd like to review some of the exchanges.

Another thread that has proven very helpful to a goodly number of forum participants can be found by following this link to information about How Water Behaves in Container Media. You'll find it a fairly detailed discussion about container soils.

Take care. Good luck and good growing!



clipped on: 01.16.2014 at 08:12 am    last updated on: 01.16.2014 at 08:12 am