my concern was that the coir/peat/perlite mix may be too clumpy/muddy - i was hoping the perlite would break it up some. i thought of throwing in some humus and compost. thoughts on this? The trick is a mix that is always moist, but also supports good aeration. I think that the peat/coir/perlite will probably achieve that, but not for more than a season as they will begin decomposing and breaking into smaller sizes quickly. As this occurs the water retentiveness of the mix increases, but at the expense of air holding capacity of the mix. Compost and humus would likely make the problem worse. I don't know what humus is in this sense as the stuff sold in bags isn't what I consider humus, it's often sawdust like stuff from what I have seen, but haven't looked in a few years. Compost will also break down very quickly. What many growers use is pine bark as the basis of the mix. It also breaks down, but more slowly and it starts at an appropriate pH. Filix has reported good success with his blueberries in Al's 5:1:1 mix (5 parts pine bark fines, 1 part peat, 1 part perlite). If you are concerned about the suitability of any mix you can test it in a clear cup. Fill the cup with mix, saturate it with water and then poke a hole in the cup so the water can drain. After no more water is draining, look to see if there is a water layer on the bottom. This would be the perched water table and blueberries aren't going to like it. If you just have an inch or less and you are using a reasonably tall container it's likely not going to be an issue, but if you have much more than that you are taking a risk with the shrubs. Keep in mind the organic component of any mix is going to break down over the season and the PWT will increase in height as it does. Some materials break down quickly, others more slowly. so, justa, i've read many of your responses to BB/soil pH, and i welcome the difference of opinion that you and i seem to share - i find soil pH paramount, you don't seem to, rather you attain it via watering and fertilizers. It isn't that I consider pH unimportant, but rather it's next to impossible to control without continual monitoring. As you saw from the link you posted the pH of the mixes shifted throughout the test. With a quality fertilizer intended for hydro or container use many nutrients will be chelated and available to the plant even when the pH is out of normal bounds. Unless one has testing equipment and is willing/able to respond appropriately to control pH swings (occur quickly and are short lived) and shifts (a longer term movement) it's not really worth fussing over, in my opinion. Rather, by building a mix that starts out with an appropriate pH range, and neutralizing the alkalinity of the irrigation water via vinegar or using rainwater when practical there should never be a problem. Something to keep in mind is that the plants are getting nutrients from the water and whatever nutrients are dissolved in it, not (so much) from the growing media. If the pH of the water/solution around the roots is good, then the plant is happy too ;) BTW, are you a veterinarian? Just wondering due to your handle/name/alias ;)

Linchat, You appear to be confusing two different things: The pH of the water and it's alkalinity. They are very different. The pH is whatever it is, but alkalinity is how well buffered it is at that pH. In other words if you have basic/alkaline water (above 7.0) that is pH. How much acid it takes to reduce the pH or how much acid it can neutralize determines it's alkalinity. If the alkalinity (buffering capacity of the water) is low the pH almost doesn't matter as it will end up becoming whatever the 'norm' is inside the container. The pine bark, for example, will lower the pH of water that has low buffering capacity. If the alkalinity is high then the water will shift the pH inside the container toward whatever the pH of the water is because it will neutralize the acids in the bark over time. The higher the alkalinity, the faster this occurs. You can measure the alkalinity and pH at home inexpensively, but if you are getting municipal water the easiest way is to call the agency in charge of the water and just ask them the pH and alkalinity. (I just read you have well water. Do you have a water quality report from it? It should list pH and alkalinity on it) Alkalinity is typically expressed as milligrams per liter (mg/l) of CaCO3 (calcium carbonate) even though it's unlikely all of the alkalinity is from calcium carbonate. If the number is less than 150 you have no worries. Between 150-300 you may want to consider neutralizing the carbonates and bicarbonates with vinegar. Abouve 300 and you either neutralize them or you watch your mix change in a single season to whatever the pH of the water is. The question is.... Once the mix has turned Alkaline, will it return to its acidic nature? Probably not as you are continually introducing the same water to it. To give you the shorthand version of how to deal with water high in alkalinity I will give you some tips. It does sound like your water is high in alkalinity, but I encourage you to be certain before you go through any trouble of dealing with it. Also, you will have a devil of a time doing anything about it as long as your containers are watered via drip coming off your lawn irrigation system. What you need to do is acidify the water to use up the carbonate and bicarbonates. You will need a fairly reliable means of testing pH. Reduce the water pH to 5.5 and the buffering capacity (alkalinity) will be fairly weak and fine for everything. Reduce it to 4.5 and there will be zero carbonate/bicarbonate ions left, they will be exhausted. A small amount of ordinary household vinegar (white distilled is usually cheapest and works great) will do the trick. With my own water with alkalinity above 400 4 ounces of vinegar in 4 gallons of water completely removes all the buffering capacity of the water (makes it pH 4.5). There are sources of 'accurate enough' test strips to measure this with if you don't care to purchase moderate maintenance electronic meters. I simply use these. They only measure pH down to 6.0, but it doesn't matter. They also measure alkalinity to 0. Make both squares on the strip glowing yellow and you are good to go ;)

Replying here to bjs496 regarding water acidification... Yes, I use a method adapted from Bamboo Rabbit's formula. I mix 2 liters of 33% sulphuric acid to about 4.5 gallons of rain water which I keep in a 5 gallon jerry can. About 1/4 a cup makes about 5 gallons of my local water a pH of 6; a 1/2 cup is about 4.5. I use a pH strip to calibrate and a Kelway soil tester to monitor my soil. It's pretty easy once one gets used to it, and no more dangerous than working with laundry bleach, at least once the diluted solution is made. It works wonders - keeps my pH right at 5.0 (or wherever I want it - I'll lower it slightly if anticpating rain, etc). Sulphuric acid is better for the roots than any other kind of acid, including vinegar. Care must be taken when mixing the first, concentrated solution, but it's no more dangerous than adding acid to a car battery. The acid itself cost me about $9/liter, $18 dollars to fill up my jerry can. I use about $30 a year acidifying water for my 18 blueberries (14 northern highbush, three compact southern highbush and one half-high). In my first year, my blueberries have reached 3 1/2-5' tall each, extremely healthy and vigorous. I also use rain water, but I always run out of water in-between rains due to all the blueberries I've been adding to my plantings (I plan to buy a bigger rain barrel next spring). If you can solve the water problem, growing blueberries is a cinch - if one is relying on tap water and soil sulphur, it's a pain in the arse. My blues get the 1/4 cup treatment every time I water and the 1/2 cup treatment any time we've had heavy rains and the pH has crept up. On the last batch of solution I made, I also added a cup of iron sulphate - helps keep my iron level very high, while adding it in small increments.

For one plant, buy the mix as suggested. But, peat moss doesn't have enough nitrate to bother (or help) the blueberry. So long as you are talking about the baled Sphagnum moss peat that is commonly sold in the compressed bales, not reed peat in regular bags such as fertilizer or most mulches and soils come in. That peat may or may not be OK for blueberries and it would be hard to tell without trying it. It could have too high of a pH. It also could be as high as 4-5% nitrogen, but not as nitrate.