If you are using a peat based potting mix, it will most likely be slightly acidic.

It's prolly not necessary, but how do you feel about vinegar? What liquid fertilizer are you using?

Al

Blood meal & cottonseed meal are organic too, but will not break down to acidify the soil as fast as vinegar.

vetivert: did you mean if I use the coal ash as "ferliziser" for the rose, it can help provide the acid needed for the plant and keep it from having black spots on the leaves?

Many thanks for your advice.

Xuan

Thanks, everyone for the suggestions. Al, I use an organic fertilizer (Dr. Earth??) Anyway it had higher proportions of everything compared to other organic choices. If I go with vinegar what proportion to water would you suggest I use and how often? The container is pretty large - 24 inches across. nhardy, I do have cottonseed meal - didn't realize it was acidic. Is alfalfa too?

What is your soil? If its a peat based soil its probably acidic enough. Have you gotten the Ph tested? Is there a problem with your roses? Why would you want to mess with the Ph?

My rose was potted in Monrovia Custom (potting) soil last year. I'm sure it is balanced. The only reason I want to make it more acid is that this particular rose (Reine des Violettes) likes a more acid environment than the average rose. Many people experience foliage problems with this rose; some leaves even turn white. I haven't found this to be the case but it is not flourishing either. So I thought acidifying the soil might be good for it.

Alfalfa meal is 3-2-2. Not as acidic as some. Cottonseed meal is 6-1-1, a slow release fertilizer & adds acidity to the soil. Ground from cottonseeds which is a natural fertilizer considered by many to be the second best source of nitrogen after blood meal. Blood meal is 12-0-0.

I hope Al comes back & can suggest the ratio of water to vinegar to feed your rose now & you can always use a slow release fertilizers too.

Maybe you have these other items too: bat gauno, coffee grounds, feather meal, crab meal, soybean meal, corn gluten, fish emulsion. I'm going to use straight vinegar to kill some of the tree seedlings that came up this spring. Vinegar is a cheap killer that I love using.

One capful of white vinegar per gallon of water.

Josh

Josh,
The vinegar I buy in a large jug, is a flip top.. LOL!

so would what you are using be about a teaspoon? I think I read somewhere, to use a teaspoon.

JoJo

That would be fine! ;)
Slightly more or less vinegar won't hurt.

Josh

Thanks for the acidifying info. The small pots of ivy bought from WalMart or Lowe,s have been dying after a few weeks despite water and humidity. Measured pH and it was 7. It is known that ivy requires 6-6.5. Why do they use neutral medium. Hope the acidifying helps.