It might work OK, if your irrigation water is free of calcium and magnesium. Is there limestone in your area?

Blueberries like acidic, poor soil. You may want to try covering the pots if you find that the soil in your area isn't amenable to blueberries.

Thanks for the responses. Today I checked on my potted blueberries. The plants are in wine barrels with about 6 inches of leaves on the surface. The soil right on the surface was thawed but everything below that was frozen solid! I hit it with the end of a shovel and it felt like concrete. I hope the plants aren't dead.

I dug several holes today, each about 20 inches deep and 30 inches in diameter. I filled them with a mix of mostly small fir bark but also a bit of peat and potting soil. I will plant into these soon with some new plants and hope that they do well!!

RM

Blueberries grow best in well drained organic soils with high water tables. Soils that are too heavy can lead to root rot and can be difficult to maintain a low pH. Rather than amending the soil it might be better to build a berm of organic material and sand and plant the blueberries there. This is common in Australia where soils are often less than ideal for blueberries. If you have gutters on your home you can purchase or make a rain barrel for irrigation water. Rain water is naturally acidic and is better for watering blueberries than well water which often has dissolved calcium and magnesium. However this is only practical for a small number of blueberry bushes.

Blueberries are not difficult to grow if given the right conditions. Proper nitrogen fertilizer is also important. Urea and ammonium forms of nitrogen are best. Avoid nitrogen in the form of nitrates. Blueberries are easy to burn so it's best to fertilize on the lean side.

Not sure what your winter is like but it does sound cold. Here in michigan I try to bury any pots of perennial plants I'm trying to over winter. Roots can freeze with little damage so long as the temps are not too extreme. It's those short bursts of frigid temps that kill plants in pots. If you can move them into a garage where the nighttime temps will be much more moderate they should be fine. Just make sure the pots don't dry out too much.

Hope this helps and good luck.

I'm surprised you haven't gotten more response as this is a common question here. Lots of people grow blueberries in the west and many methods are used.

As was mentioned, you need to know the pH of your water and if it is a municipal source you should be able to find out with a couple of phone calls. You can also use a pH kit from a pet store (for aquariums). You can acidify your water with citric acid or other buffer- even vinegar.

If you're not constantly raising the pH of your soil with your water your method will work fine if drainage is good but the surrounding soil will suck water from your little islands like nobodies business. They still won't dry out as quickly as exposed pots, however.

You can also just put the pots in the soil and get similar results.

People out west have successfully grown blueberries straight in bales of peat moss with the plastic still attached. I guess this reduces the need of replacing water.

The way generally considered best for the acidification of soil is to use pelletized sulfur.

My water here has a pH of about 7 so I will keep an eye on that. I am hoping that by adding new bark to the soil surface that the low pH will be maintained over time. Thanks again for all the kind responses.

RM

Bark will not keep pH down over time and will not in itself lower the pH significantly- at least as far as the over all soil. However, I believe that keeping your plants mulched with it will sustain a thin acidic line at the soils surface where the plants can draw adequate iron.

I have heard of people maintaining healthy blueberries in soil with a pH close to 7 and I've seen healthy plants with pH in the mid 6's where they've been annually mulched but I've never seen these observations confirmed in the literature.

I usually strive to keep the pH in the mid 5's at the highest and use sulfur to do so. Peat is not a long term pH fix when used as an amendment because it breaks down and loses influence with declining bulk, I believe.

Your comments are interesting and I appreciate your thoughts. This is an experiment for me and I definitely don't have all the answers. I have some blues doing well in pots and the soil mix I am trying in the ground is the same.

I am in southeastern Washington in a huge agricultural area. More than 150 wineries in my hometown, tons of vegetables, orchards and dryland crops, fantastic soil.

Home gardners here successfully grow azaleas and rhododendrons by using a significant amount of fir bark in the mix and the topping with bark periodically.

I know of only one person in this town that is growing blueberries in the garden, the plants are thriving using a method identical to what is used to grow rhododendrons. There are a couple of large blueberry farms in the area but I believe they are using ammonium sulfate to control pH.

RM

Sulfur will get the same results over the long term as A.S..
Commercial growers don't always use an organic mulch because of the expense of application, but it's generally a well endorsed commercial production technique.

If a local gardener is doing something that works and isn't complicated, I'd just run with that as my first trial. It's bound to work for you.

Thanks harvestman, I will report back as the season progresses.

RM