I grow blueberries in Madison, Wisconsin, and both our soil and our city supplied tap water are alkaline, with pH around 7.6. There is a lot of limestone in southern Wisconsin, both underground, and on the surface. So this is how I plant blueberry shrubs, which do best in acidic soil with pH at 4.5: Dig a hole 24 inches wide by 16 inches deep. The hole should be considerably larger than the root ball, so the roots have room to expand. Put 3/4 cup of agricultural sulfur in the bottom of the hole, and fill the hole to halfway with peat moss. Add back some dirt, and mix with the peat, until there are no lumps. I do this by hand, with a garden trowel. I'm sure it would go faster if I had something with a motor on it. Prepare the shrub for planting, and separate or rough up the roots. Often, potted shrub will be "root bound," meaning that the roots are tightly compacted within the pot, and wrapped around the perimeter in a tight ball. This knot of roots has to be cut open, or broken open, so the roots will be able to grow laterally and penetrate the soil. The shrub is immediately planted in the soil, with more dirt added as needed to fill in the hole. Add 3/4 cup of agricultural sulfur to the surface, around the shrub, and cover with 4 or 5 inches of mulch. Immediately water in the shrub, typically with about 8 gallons of water. The base of the shrub should be even with the surrounding soil surface level, as it was in the pot. Blueberry shrubs will need to be watered once or twice a week for the first 6 months, depending on rainfall. It takes two years for soil bacteria to metabolize the sulfur, and lower pH. However, the peat moss will lower soil pH enough to get the plant started. The soil pH should be tested at two or three year intervals, and more sulfur can be added as necessary, depending on the results. I do not add sulfur when the pH is below 5.

ericwi's directions were good for azaleas also. The only thing I would add, it helps to use a raised bed. The azaleas have very shallow roots, so the raised bed doesn't need to be very high, 6 to 8 inches.

Don't use either the rabbit manure or miracid (Miracle Grow Azalea Food). They are both too high in nitrogen. A much better product is HollyTone. It has organic nitrogen which doesn't damage the mycorrhiza in the soil, which is very valuable to azaleas. If you use HollyTone, only use at half the rate on the package and do not use after mid-June. The earlier the better.

Here is a link that might be useful: How to grow rhododendrons and azaleas

THx ericwi and rhodyman I'll give it a try. Hoping for good luck. Would the same method work for rhododendrons ?

Azaleas, rhododendrons, mountain laurel, cranberry, bearberry, and blueberry all belong to the plant family Ericaceae, & to my knowledge, all of them grow in acidic soil. Blueberry does best in full sun locations, while rhododendron is generally found wild growing under or near trees, where it is partially shaded. The soil requirements are similar, but the optimum habitat is different.

Not only are azaleas and rhododendrons both members of Ericaceae, azaleas are rhododendrons. Their culture is basically the same with some variation between different varieties.

There are basically 6 different groups of rhododendrons:

1) Elepidote Rhododendrons: Rhododendrons without scales, typically the larger leaved rhododendrons.

2) Lepidote Rhododendrons: Rhododendrons with scales, typically the smaller leaved rhododendrons.

3) Deciduous Azaleas: Azaleas that typically put out new leaves each spring and drop them in the fall.

4) Evergreen Azaleas: Azaleas that put out spring leaves and then summer leaves. Neither set lasts a full season.

5) Vireya Rhododendrons: Lepidote rhododendrons that are tropical and will not withstand a freeze.

6) "The Other Rhododendron Groups": The misfits: Choniastrum, Ledum and Therorhodion

Here is a link that might be useful: Differences between rhododendrons and azaleas