As a general rule, those who grow blueberries in pots filled with a mix referred to as a "medium" are planning to apply dilute solutions of water soluble fertilizer periodically. Is this your intent?

Brady,
Any acid mulch is good, including cedar and oak. It's true that a layer of mulch will sequester nitrogen from the soil and even the compost. Fertilize in spring at budbreak and double or triple the amount of non nitrate fertilizers in a dilute fashion up to 2' from the base. Ammonium sulfate counters the hardness if watering with hard water. Make sure to deep soak when watering as an inch of rain wont do. Even pine needles break up nicely and are awesome. Apply mulch 3-4" thick, every 2 years,expanding the mulched area.
Sounds like you're on the right track. You might want some granulated sulfur to apply before mulching. Try a different search as there is tons of previous postings on the subject. Good luck to you.
Noogy

Use the finest pine bark mulch you can find (it is usually labeled "soil conditioner" here but maybe SoilPrep there) and don't worry about it not being composted. At worst you will need to add a little bit more N for a while. The easist way to deal with this for the first year is an occasional supplementary foliar spray with Miracid or some similar high-N complete nutritional spray while the bark "composts." I have always suspected that bark while composting takes up less N (or perhaps less rapidly) than sawdust but I don't know that for a fact. The southern highbush bluberry industry in south Georgia and northern Florida uses prodigious amounts of pinebark as soil. I don't recall any mention of composting first. You might Google some university ag literature on that topic.

Thanks guys for the information.Yes ericwi,I plan on doing what it takes to help these plants.The ones without fruit have been getting the treatment that fruitnut wrote about, a tablespoon of Ammonium Sulfate diluted in approximately two gallons of water,once a week.The others were given some Cottonseed meal sprinkled around the drip line.
I'm still learning about growing these things and in some way am trying to find the ideal conditions,even though from what I've read,they thrive in some fairly poor soils.Thanks again,Brady

Blueberries will green up and grow in poor soils, if the pH is low enough. They do well in pH range 4 to 6.5, but they seem to do best when pH is between 4 and 5. Unless you live in an area with soil that is known to be on the acid side, you will have to do some pH testing sooner or later. Also, the water you are using on the shrubs might affect pH, if it is hard water, that contains calcium carbonate. You can set up the soil for success, but still have problems with chlorosis if the water raises pH. Rainwater is either neutral or acidic, so that is preferable.

The ground soil where I live in Redmond,Washington is about 6.5pH and the tap water is near 7.2pH.Just about from day one,I've added a little vinegar to make the water close to 5pH.Lately,about a cup of soil sulfur has been added to the mix.My rain water collection ability is very limited right now,although it is fairly acidic.
I'm looking into installing a drip system with the intent of injecting some vinegar or mild acid.Brady

I think its easier to grow blueberries in the Pacific Northwest, due to favorable soils. Here in south-central Wisconsin, its a different story. Our soil has pH around 7.6, and our groundwater/wellwater is about the same. So there is a learning curve involved with blueberries.

I gorow in straight pine bark fines, and feed with fish emulsion and seaweed extract. Works more than just fine. I also like to use alfalfa hay as a mulch, about 2" thick. Foliar spray with a compost tea 1X per week, when possible. Planted in 1/2 oak barrels.

In answer to your original question. Uncomposted pine bark mulch will look like freshly chopped up bark, basically brown in color. Partially composted or composted pine bark mulch will look black and have a decomposed look to it. I didn't know the difference either, but when I saw both side by side it was fairly easy to tell the difference. I usually start out with an uncomposted brown mix in my containers and after one year it turns black.

It's been a while since this thread was started.The stuff I first mentioned is still being used,so it's probably the right kind,as the Blueberry plants are doing well. Brady

Guess I should look at when a thread is started huh? :-)

I use one year old Pine bark its piled out in sun rain mixed couple times year with large front loader works good in large pot, but takes a lot watering if don't rain. I'm now trying composted Cotton Gin Trash pile out open at Gin that holes water longer both materials are black has some sand in mix.

Newbie blueberry grower here from WA and I was wondering about this question as well. Sorry to resurrect this zombie, but I thought future lurkers will find this useful.

The research I've found supported what Bradybb was seeing. The paper Fresh and Aged Pine Bark as Soil Amendments for Establishment of Highbush Blueberry mentioned "that pine bark
amendments improved plant growth and yield
due to modification of the soil physical
structure rather than soil chemistry." Though due to low moisture capacity, bark amendment should not be used in gravelly soil, but use peat moss instead.

Compared to peat moss, "there was a tendency for plants in
the bark-amended plots to have slightly greater
plant height and spread, more new canes,
and higher yields. All criteria were within
normal range." My take is that this is not statistically significant enough for any conclusions.

I agree not conclusive. I see the main point as being that the addition improved structure (code for 'drainage'.) Although being acidic in nature, it seems like the addition of bark or peat is a no brainer to improve soil chemistry for blueberries a "little" bit.

Also note that while wood mulch does take up nitrogen, as it composts it also gives back all of that nitrogen, so there is no net loss. You can always add nitrogen via organic sources like ammonium sulfate or your own free nitrogen - urea (blueberry plants love it).

Much of the nitrogen in wood chips finds it's way to the air. So a net loss.

I'm now using Conifer bark mulch as a structural helper,to give the plant's roots more breathing room and so water flows better.I can add Nitrogen very easily if needed. Brady

Could you expand on the conifer bark Brady (you mean like cypress?) I thought one of the benefits is that it gives better soil structure i.e. breathing room for the roots. The local store has chunkyish pine bark nuggets and shredded cypress mulch, I've been thinking of using the former in maybe 50/50 ratio with some potting soil when I put my sunshine blue in a 15 gallon?

"Much of the nitrogen in wood chips finds it's way to the air. So a net loss."

We are not talking about wood chips but rather pine bark nuggets - a very different kettle of fish. The pine bark is intended to be part of the potting medium, which is not at all an appropriate use of wood chips. When incorporated into the container medium, there is virtually NO volatilization of N from pine bark so no net loss. Plus any containerized plant will require routine fertilization regardless of the potting medium - that is a fact of life of ALL container growing so any N that may be lost is easily replaced.

FYI, volatilization, or loss to the atmosphere of N is pretty darn low with wood chips anyway. The high C:N ratio of this product helps to immobilize the inorganic N that would otherwise be susceptible to NH3, volatilization and to some extent, leaching. So very likely no net loss there, either.

Let's get your facts straight, Drew!!

You are once again incorrect (this is getting rather embarrassing for you), Best do your homework. People often fertilize adding large amounts of nitrogen so much for your C:N ratio. Some is always lost to volatilization. I guess I should have said some instead of much. It always is a net loss, there I am correct. So please stop making false statements, and putting words into my mouth. You are hurting many users here with your extremely bad advice.

I agree bark by itself losses little nitrogen (as it has virtually none!), but we are not talking about that. We are talking about the nitrogen added to the bark and the fact as bacteria utilize the nitrogen to breakdown the bark, not all is is returned as stated. that is incorrect. Some is lost to the air. Nobody I know disputes that except you. I have never seen a study where the breakdown of bark by adding additional nitrogen, that nitrogen is 100% retained, it is not. Chemistry 101. bacteria release the nitrogen as NH3 when they die. Well some of it, to be clear this time.

The question was is fresh bark bad to use? Well not really but you will lose some nitrogen so one should take that fact in mind and give a little extra for the composting of the bark. Using composted bark, you don't really need to worry about it. Add normal amounts of nitrogen. You should know that.