Depends on the fertilizer. In general nitrogen is the first nutrient to run out the drainage hole, but if you are using a water soluable fertilizer like Peters or Miracle Grow or anything you mix with water before using then it all runs out the drainage hole ;-)

You will have to experiment to find what works best for you, but a decent starting place is to use some slow release nutrient like osmocote mixed into the mix at planting time as kind of an insurance policy, but then pretend it isn't there and develop a fertilizing routine that works for you and the plants. This involves a water soluable fert of whatever kind is appropriate and either using it 1/4 strength or so with each watering or half strength once a week or full strength every other week or whatever. There are as many variations on the ferting routing as there are container growers.

For best performace either add a micronutrient source at planting time or use a 'complete' fertilizer that has the micronutrients in it as container mixes generally have little to no micronutrients in them and the plants will do best with them. Tomatos in particular are more susceptible to blossom end rot in containers. Part of this is probably due to inconsitent watering (try to keep them moist at all times), but some times it may be due to no calcium in the mix.

There are synthetic ferts that are 'complete', but you can also use a few organic ferts which naturally contain some or all of the minors like fish/seaweed products and others.

Thanks. I started off with Peter's starting mix and added generous amount of compost.
I have some seaweed emulsion...I'll give the pots a dose of that.
Thanks again.

I wouldnt worry about fertilizer now I would wait until the rain is over and the pot soil is dry enough to need water, then feed and water on your regular schedule.

you might want to worry about soil pH depending on where you live and the pH of your rain.

Just a couple of notes: You should not fertilize a dry plant. The salts in the fertilizer, combined with the salt residue in the container can osmotically "pull" water through cell membranes from the succulent parts of the plant (roots) and cause plasmolysis (fertilizer burn). Be sure the plant is well-hydrated and soil moist before applying fertilizer solutions

Chasing soil pH in container plantings, at least for the casual or hobby grower, is pretty much futile & largely unnecessary. The organic particulates we grow in hold nutrient ions very loosely, making them available over a much wider pH range than in naturally occurring soils.

Al

try growing blueberries in pots with a bad pH.

figtree, what Al says is true....for nearly all container plants that you may want to grow, pH will never be a consideration....so don't let the mention of that concern you. If you decide to get into some real acid loving plants (like blueberries), then you will have to address the pH.

pH wont be a problem unless you get 6 straight days of rain with a pH of 4.5 or lower. you people are crazy

Wow. I'm stepping over the gauntlet you dropped to get at your knowledge. I'm hoping you'll share all you know of managing container soil pH if no one takes exception to the inference of insanity. Let's cut him some slack & see what he has to say? Please, take all the time you need - you have a rapt audience.

BTW - I'm probably a little loony, so I can't take exception to your comment, but from what I've seen in hundreds of helpful comments by Rhizo, I'd have to say that you probably made your assessment too hastily. ;o)

Al

I would agree container ph isn't terribly important with the exception of plants like bluberries which require low ph.

Even then the mix in the container isn't important unless the mix is all lime or something.

What is important in a container is the water and the ph of the water after nutrients are added if nutrients are being added.

If the water carrying the nutrients is in a ph range appropriate for the plant it works out.

Now, Al, I am curious for more information on this statement "The organic particulates we grow in hold nutrient ions very loosely, making them available over a much wider pH range than in naturally occurring soils."

I would assume that in your mixes the organic matter is primarily bark pieces, but in a 'typical' mix the particulates would be peat and in some ppls mixes there would also be compost. Would the same hold true there?

I keep learning about ph and what it's effects are, but the more I learn the more I realize I have to learn.

if you honestly dont think that a weeks worth of acid rain isnt going to affect the pH of your soil then go right ahead and believe it.

as for me,i know it does and make amendments to my container plants when it does happen.

did i ever say you need to monitor pH like a hydro setup??NO, did i say you had to "chase" container pH?NO

i did say you might be concerned with your pH if you had excess rain on your pots depending on rain pH..SHEESH!!

What will impact any soil or mix would be what the buffering capacity is (in either direction - acidic or alkaline). If there's nothing in the mix to help stop the pH from moving out of a certain buffer's range, then the water can eventually impact the pH of the medium when aqueous. Usually it takes a strongly acidic or basic water over time to defeat whatever buffer compound is there in a commercial mix. Those who hand-water with alkaline-pH water (often those out west or down in TX, etc.) have a similar issue with the change in soil pH and often post about it.

Wow! As always, thanks for the illumination. I'm a casual gardener who is always interested in relevant info, however, not (yet) such an enthusiast as to test conatiner PH.
I did add lime and compost before planting. Our water is 'hard' and I'm not yet realizing the effects of this on my vegetables. Would 'hard water' lean toward acidity or alkaline?

pH meters cost 5 bucks and take 2 seconds to check pH. you dont have to do it everyday, i dont know where the people on here got that idea.

fig, 'as a general rule of thumb', hard water tends to be alkaline. It's not always the case, but typical. I've never in my life tested the pH in my container medium, by the way. But I do believe that it is important to have a good idea of the pH of your in in situ soil. That way you won't be applying lime or other pH alterning amendments when you shouldn't.

ut, I 'think' you're over reacting just a tad, don't you? ;-) We're all pals, here. Good points made by ALL!!!

rhiz,

im not overreacting, just dont like when i see "bad" advice.

and ive noticed you come in behind me on multiple threads and do just that, so i have to clean up the "trash"

Let it go Dorie. This guy has contributed nothing to the conversation in the way of enlightenment - he obviously has nothing to offer but opinions he's reluctant to provide substance to support. Intercourse with him is bound to produce more heat than light. Use of the sites search function with his forum handle as the searchword will lend more insight.

Al

water your containers with water that has a pH of 4 for a week and tell me your pH doesnt change.

how much more substance do you need?

LOL,

tapla i just searched your name and found countless posts where you just type so you can hear yourself. you seem to like to tell people when and why they are wrong.LOL, you even made a point to say just because someone has done something for 90 years and had no problems doesnt make it right,oh the irony!!! you seem to like to say to others when they disagree that they arent "backing" up their words, then you type about 4 pages of BS. LOL!!!

TALPA,

you might want to read this thread.not only does it back up what i was saying about low pH of water causing soil pH to drop but also gives another reason. 2 GOOD reasons to have a pH meter to occasionally check soil pH, especially if your plants are showing neg signs.

http://forums2.gardenweb.com/forums/load/soil/msg072327022059.html?10

peace out!! this place is chopped full of pompous haters!!

figtreeundrgrnd - "hard" water generally means it has a higher "alkalinity" than normal and the minerals in that "hard" water tend to help the solution self-buffer in the more alkaline range, even with the addition of weak acid. However in the presence of a strongly acidic environment (whether through substances in the soil or acidic water), the buffering that is going on eventually begins to break down and the carbonates and/or bicarbonates further disassociate in solution with the excess H+ ion present (often coming from sulfuric or nitric acid - components often found in acid rain). The U.S. has regulations to reduce acid rain by requiring scrubbers in industrial smoke stacks but unfortunately we can't filter out emissions that swirl around the globe from other places.

Geez! I didn't mean to start world war three!
utsharpie, I'm no expert (hence my innocent request) but I'm sure if I pour vinagar in those two dinky containers the PH would change!
I have a PH tester as I'm growing blueberries (in-grnd), but, again, my post concerned fertilizer and depleted nutrients. Yes, I have learned that PH effects how nutrients are taken up... I'm sure I could also sent a soil sample to my local extension service...but really!
Thanks to all?

correct fig, my point wasnt that pH is hard to figure out or even to correct but it is important and very EASY to test.and is very pertinent to your question.

no need for a PhD or soil sample sent in.

Is there any statistics on the pH of rainwater in different areas of the U.S.? Are any particular areas known to have more acidic rainfall, and if so, what pH ranges are we talking about? I'm curious about what the worst areas are, and how container gardeners in those areas deal with it.

I've seen pretty versions of the map, but here it is : http://water.usgs.gov/nwc/NWC/pH/html/ph.html

In container media, pH increase results from neutralization of H+ in solution by the supply of usually either HCO3- or OH-, depending on the source of liming material (In the case of most container gardeners this will be fertilizer, though some that make their own soils are now using dolomite or other sources). Changes in pH subsequently affect a soil's cation exchange capacity (CEC). Changes in CEC affect a substrateÂs capacity for binding nutrient cations, with an increase in CEC allowing more cations to adsorb to the substrate particles (not a good thing). As a result, an increase in pH associated with lime additions often results in decreased macro-nutrient and micro-nutrient availability in both bark and peat-based media. A study by Haynes and Swift (1985), and by Peterson (1982) listed pH 4.0 to 5.2 as the optimal pH range for nutrient availability in soilless substrates. A recent reading of a paper on pH's effect on container grown nursery and ornamental material submitted for a master's degree in horticulture supports the finding that container-grown plants gain most biomass when grown in media with a pH like that listed above - much lower than you might think.

From this, it's pretty simple to extrapolate the conclusion that rain water in the pH range of 4.0 or even a little lower is not likely to present much (or any) difficulty to plants unless they are lime-loving plants.

If a hobby grower tells you he manages the pH of his container media, you can be very suspect of his veracity. Container substrate pH fluctuates wildly and is affected by a number of variables, so even checking daily with a reliable pH meter will leave the uninitiated scratching their heads over what is causing so wide a variance. How can we possibly make corrections when readings are so likely to be "all over the place"? As an illustration, my "management strategy" consists of using an acid forming fertilizer for those plants that appreciate a low pH, and a base forming fertilizer for the very few plants I own that prefer a high pH. I own neither a pH meter nor a moisture measuring tool.

Figtree - If you're still hanging here: Yes, nutrients will be washed from containers at varying rates, and substrate pH does have an effect on which will be lost first because nutrients become most soluble at (in) a particular pH (range). A review of the chart I provide in the link will give an idea of what nutrients are most soluble at different pH levels.

Al

Here is a link that might be useful: Let's go see the chart

singing a different tune huh AL?

amazing how much crap is always slung my way and then they realize, hey, he was right.

soil pH is important even in containers as it can mess up your ferts

Be sure to read the ingredients statements on typical fertilizers like Scotts brands (Miracle Gro, Osmocote, etc,), Peter's, Espoma, etc., because they generally are not made to alter pH outside of those specialty products that are formulated to aid in reducing pH (eg., Hollytone with its elemental sulfur, etc).

Ie., these commercial fertilizers are not adding carbonates as mentioned above. If you want to increase pH, you need to add it separately via hydrated lime, dolomitic lime, etc.

About a year ago, I recall listening to a radio garden show where one of the VPs of Promix was on and he described generally (without obviously revealing their trade secrets) how they formulated their mix, which included materials like lime that would pH adjust the mix to ~pH 6.5 when aqueous. That pH has been found to be a good for a broad range of plants (outside of the acid-lovers), as most of the common macro and micro nutrients are available at that pH. However, once the buffering substances are consumed and leached, the pH can go either way unless something is added back.

There are a number of cool pH/nutrient availability charts posted around the web. The below links to one from Cornell.

Here is a link that might be useful: {{gwi:35255}}

I did a PH test and my range (today) is btwn 7-7.5. According to these charts...my tomatoes should be happy and receiving most nutrients.
If we get another good down pour I'll check again...more out of curiosity than any intention to alter PH. I would be surprised to see any severe variation one way or the other.
Thanks for the info.

Let us know what you come up with, figtree. You are smart to use the pH meter after a heavy drenching, every time. As someone mentioned above, the meter is reading what's going on in the water, the dissolved minerals from fertilization, etc. Truthfully, your pH reading could fluctuate enormously from one day to the next, depending upon several factors. Testing under conditions that are as similiar as possible will help you get results that might be remotely meaningful.

I can taste those 'maters already!!