Yes,that will be okay with the Sulfur and your fertilizer or a little Ammonium Sulfate. Brady

Sounds like they aren't getting enough fertilizer. Try applying some every week. Just be sure it's not too concentrated and they have plenty of water. They should grow 2-3ft a yr if pushed with fertilizer.

Are there granular fertilizers for acid loving plants like blueberries? I'm not sure I will have the time to follow through on weekly feedings.
Liz

The linked below from Amazon should increase your plants growth.

Here is a link that might be useful: controlled release acid loving fertilizer

I would also try some ferrous sulfate. They are
being deprived of iron with the higher Ph. Are the
leaves yellow or pale green?

I have elemental sulfur. Is there a difference between the ferrous sulfate and the sulfur powder?

Blueberry shrubs will thrive if the soil pH is down around 4.5. There should be some vegetable fiber, or organic matter, in the soil, to feed the fungi that live in symbiosis with the blueberry roots. If these conditions are met, and if the shrubs are given enough water, they should approximately double in size every year, until they are about 5 years in the ground. Here in Madison, Wisconsin, we have naturally alkaline soil, with pH around 7.6, so I have to lower the pH around each blueberry shrub in order to keep them growing. Since the shrubs are scattered around the yard, at various locations, I do multiple pH tests every year, about 10 soil tests total. To keep the cost of testing down, I do my own pH testing, using bromocresol green indicator solution. A five dollar bottle might do 100 tests. Add in the cost of the filter paper, and the DI water, and each pH test might cost around 25 cents. I am using agricultural sulfur to lower soil pH. This is a slow method for lowering pH, and it can take two years for an application of sulfur to be completely metabolized by soil bacteria. But there are two advantages to this method: 1-sulfur, in 50 lb bags, is inexpensive, and 2-sulfur is relatively non-toxic and safe to store.

Iron sulfate has come up a couple times recently. My understanding is that the benefit of iron sulfate is not the addition of iron to the soil chemistry. The bb's still cannot use the iron if the pH remains high. The beneficial function is that it lowers pH more quickly than ammonium sulfate our elemental sulfur.

I use osmocote on my blueberries and keep them mulched with pine needles and peat moss ..

but more than that I wanted to tell you to look up Dimeo Farms if you have room for more blueberry bushes... they sell mature 3year old plants for $10 each.... they are picky with their timing... b/c they need to keep someone available to pick up the plants but I interplanted young blueberries with 3 YO mature ones so I could have some blueberries last year.

A trick you might want to try for a few days, that jolted some life previously into mine that were ailing. This may sound crazy, but brew a pot of coffee then make your mixture with 1/3 coffee and 2/3 water. Then water your blueberries with this mixture. I also add coffee grounds saved from where I work to mulch. To my understanding the coffee grounds have already been spent when the coffee was brewed, but the coffee is actually where the acidity goes. I saw this suggestion a while back and like I said it seems to throw some life into struggling blueberries. Of course as most suggest, a soil analysis and doing exactly what your blueberries need is a better way than hit or miss.