Azaleas, Maria, don't like to have their shallow roots disturbed. This limits your options.

What I did in CA was what you may want to do: get some pine needles and put a thick layer down before you put the compost down, then cover with wood chips from the facility where you got your compost. Or compost first, then needles, then chips. Or mix needles into compost then chips. Either way. No need to purchase products.

Dan

Pine needles provide a negligable and temporary reduction in pH- check out Google. I'm much more interested in compost with a pH in the high 7's- I thought compost should be near neutral. I'd want to know why and what's in it. Lime maybe?

The end result of compost should be a neutral ph. Even if pine bark fines and pine needles were used in the making. I want to plant raspberries in containers and was thinking of using uncomposted pine bark fines.(screened mulch) I'd be interested in what any one else has to say on the matter.

frank, I agree it isn't the best solution (but it is free), but by the same token one would expect the compost will change the pH of the native soil only marginally and slowly because of the surface application only. As for the pH, that is controlled by the material and if the materials used have a high pH then the compost will have a high pH.

I will admit yesterday I didn't think this issue thru to the degree needed and now that I am, I see that WSU had the same issue with their compost, and found that Adding ammonium sulfate and sulfur at a rate of 1 lb. each per yard, to WSU compost, was successful in lowering pH and raising available nitrogen.

So for this problem, adding the bquoted ingredients should cost little if the materials are on hand, and if not I suspect the materials can be had for around $15 with much extra (maybe the OP has friends with extra lawn fert and sulfur).

Dan

Hola,

Ever hear the expression " Hellfire and Brimstone"? Elemental Sulfur is an antibiotic, so it seems counterproductive to 'amend' soil with it to change soil pH. If sulfur is lacking in the soil it should be added in the sulfate form, though, it will still have a heating effect on the soil. In the moist spring, it might jumpstart the season, but during the summer it might drive off moisture.

I wonder if vinegar would do the trick for you and your azaleas?

Terran

Mix in lots of peat moss.

Iron sulfate evenly blended at a rate of about 1 lb. per cu. yd. will decrease the pH some and provide some available nitrogen. If you go that route, be sure to sweep iron sulfate off of any concrete or hardscape before you water. If it gets wet, it stains like crazy.

I was thinking peat moss - like Swanz suggested - mix in lots of peat moss. Dan Stanley's thoughts on how WSU dealt with a similar situation make sense - Dan seems to provide lots of helpful advise on the forums here.

First, high 7's isn't all that alkaline, it's pretty close to neutral (although like Frank I'm still surprised it's that high in the first place).

Second, if your soil is already acidic enough to grow azaleas, I doubt that the pH of the compost--especially within that range, and especially when used as a mulch or top dressing--would affect the pH of the soil very much if at all.

My advice is to use it as is and not worry about it.

....and by nitrogen I mean iron (oops)
Anyway, swanz and eatsivy are right about the peat moss. A good acid loving backfill for new plantings in a slightly alkaline soil is 50/50 site soil to peat moss with 1 lb. or iron sulfuate and 1 lb. of nitroform (slow release nitrogen) per cu. yd. of backfill.

Thank you everyone, you are such a knowledgeable group!

I will follow your advice and add Iron sulfate to it since I already have it. Thank you so much.