My understanding is plants *generally* have difficulty absorbing nutrients when pH is high. But if you lower pH, e.g. by adding vinegar to water or by other means, then nutrient absorption becomes better. Not sure if or how this is applicable to flowering plants and no-nitrogen fertilizers specifically.

But lowering the pH of the water may not be necessary if the soil pH is already somewhat acidic. I add extra peat to the potting mix in my containers for this reason. Plus, I occasionally water with distilled water (neutral pH).

I can't recall where I read it. There was something supposedly "bad" about using these fertilizers with no nitrogen in them formulated to supposedly make a plant bloom better. So I haven't used it yet. But now that the end of the summer is nearing I'm tempted, but I don't want to screw up the plants even if there's no blooms.

Soil PH and water PH are interrelated but not the same thing.

Soil PH can definitely affect nutrient availability and uptake.

Also keep in mind that hard water and high PH water are not really synonymous.

My reco would be to google the topic as best you can to see if there's some reasonably credible advice out there. Either way, the only sure way to know is to give your flowers a weak, but steady supply of the fert in question (assuming your sail drains well) and have patience. This experiment might yield better results in the spring instead of going into fall. GL

I know for sure that I've got hard water with lots of minerals like calcium in it that causes plenty of scale if you don't wipe it off surfaces. The pH is higher than 7.0, and that's because it comes from an aquifer. It's just not worth it to test the soil pH in these containers. I don't know how accurate a store bought test device would be.

If you don't use a fertilizer at the recommended dilution it may not work for this reason alone.

If it is cut and dry that when you have hard water you shouldn't use fertilizers that have only phosphorous (phosphates) and potassium, which pretty much covers these "Morbloom" type products, there is NOT good information about it available on the Internet. That's why I'm asking here.

I don't see anybody on these forums advocating 0-10-10 ratios so you might not find too much familiarity, sorry to say.

Why don't you simply use the distilled exclusively or add the vinegar each time you water so you can sleep at night? Seems all plants appreciate sub 7 PH water with 5.5-6.0 being the sweet spot.

I know you already have the 0-10-10 and are anxious to use it, but those ratios are not recommended any where on these forums. I find even my legume shrubs need a fair amt of nitrogen and they're not supposed to need any.

Hope you get the answer you're looking for from someplace.

To use distilled water all the time is too expensive. I only use it exclusively for gardenias.

One tablespoon vinegar (apple cider or plain white, both are 5% acidity) per gallon of water?

Here's a quote I found from a respected article on this forum:

"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."

http://forums2.gardenweb.com/forums/load/contain/msg0323131520631.html?88

But does this suggest you should stick with the regular fertilizer (like a 24:8:16) in low continuous dosages, or isn't it the case that if a 0:10:10 fertilizer is indeed low in nitrogen (none in fact) then the plant wouldn't receive any for a brief period, which creates the low nitrogen condition described above? But I guess you also risk increasing phosphorous too much. NO easy answer here when you're looking to increase bloom.

This post was edited by peterk312 on Wed, Aug 28, 13 at 22:48

I hope your petunias appreciate all this effort you're going through. :) My annuals are always low man on the totem pole in terms of my time and energy.

Here's a relevant excerpt from an old thread (linked below) that I found very informative:

"...there is no plant that uses P at the same rate as it uses N and K therefore a fertilizer that contains more P than N or K is useless and wasteful."

As for the vinegar issue, I strongly advise that you buy some pH strips or a simple test kit (like this one) before proceeding. Test your water, then determine the amount of vinegar that's required to lower the pH to the desired point. Otherwise, you're just guessing, and the buffering capacity of water sources varies tremendously.

Here is a link that might be useful: The uselessness of high P fertilizers

Okay. Okay. The "Morbloom" is out. Funny thing. Since I started this post I stopped fertilizing the petunias and I've got new buds on some of the plants. It's also true though that I had cut them back, as is suggested.

Where do you get that pH kit from generalhydroponics ?

This post was edited by peterk312 on Fri, Aug 30, 13 at 12:38

A Google search will turn up a variety of online retailers. If you want to pinch pennies, you'll probably find the best prices on eBay.

The link below from this forum says it all about the danger of using high phosphorous fertilizers. Good thing I decided not to use it.

Here is a link that might be useful: Don't use

the "expert" quotes above have some validity...but not entirely correct. While it is true that increasing a specific nutrient will make that nutrient more available....plants always uplift nutrients in a ratio of 3-1-2. Therefore, most quality "complete" fertilizers have the three major nutrients in that ratio...along with the other 8 or 9 minor components (zinc, calc.,etc).

I wouldn't go so far as to say that plants always use nutrients in a 3-1-2 ratio. In contrast, I think it's safe to say that plant tissue, regardless of species, usually has an npk ratio of approximately 3-1-2. They might take those nutrients up in slightly different ratios at different times, but, on average, a 3-1-2 ratio fertilizer provides a nutrient balance that meets the needs of most types of plants throughout their life cycles.