I have a few plants around the garden that really look awful. The foliage is very yellow. These include the "Just Like Picasso" Petunia in a hanging basket, Starfighter Lily in ground for 3 years, Charles Albanel Explorer Rose. I have applied iron, added gypsum and fertilizer regularly. The problem is the PH of the soil. All of the problem plants are growing in a soil PH of 7.3 or higher. I need to get the PH lower (more acidic) to 6.5 or so (try for less than 7.0). I'm going to apply aluminum sulphate to the problem areas. I am also going to try to use rain water for the containers with petunias as much as possible since our tap water is quite alkaline.

Has anyone dealt with this and/or have some comments/suggestions.

Here's a picture of the rose, which is near a old concrete driveway. I have been told that the concrete will leech over years and will be a factor in the soil PH (alkaline or higher PH). The info in the soil tester states the the high alkaline soil inhibits the plant to uptake nutrients. Guess that would be a big part with the petunia

Here's just like picasso petunia

Wow, Joanna--my Picasso petunias are growing like crazy in my garden. I can't believe how they are blooming non-stop with the goofy weather we've been having. I planted 4 plants (from 4" pots) into a 16" container, and it is awesome! Mine are growing in coconut coir, which if I remember correctly has a ph of ~6.5.

Will try to get a photo tomorrow. Even with all of the rain we've had here (last month one of the wettest on record), these plants have kept going.

Joanna...you might want to look on Anna's blogsite..aka flowergardengirl in Clemmons, NC..I think she trials for PW and had some comments about Picaso petunias on her site.

Here's a GREAT resource regarding plants, soil and pH. I have also put a quick link in the "LINKS" section of the SEEDS cubit.

http://www.plantea.com/pH.htm

Well, pine needles and peat moss and coffee grounds are said to be "on the acid side", but you might have to add a lot of them to see any difference. Gallons and gallons of vinegar, added a little at a time over months? Or Coca-Cola?

I've never read that this next idea was a good idea, but it sounds good based on high-school chemistry.
This is just speculative, approach with caution.
Add diluted acid. VASTLY diluted acid.
Don't burn your skin or eyes. Or lungs. Or plants or worms.

Probably no one advises it because it is so easy to burn yourself with concentrated acid.
Maybe it is just a terrible, dumb idea.

Nitric acid would add nitrates, but it is notoriously corrosive when concentrated.
Phosphoric acid would add phosphates - sounds good to me.
Sulphuric acid would add sulphate - perhaps too much. Does SO4 make other things less soluble?
Don't use hydrochloric acid: chloride is an unwanted ion (salinization). And the fumes stink. And bleach your nose hairs.

My first guess for diluting anything you might find at a hardware store comes from vingar being pH 2.4. If that is safe to handle, diluting the strong acids down to pH 4 MIGHT be safe to work with. That would be 10,000 to 1 - but water it in right away or see what "burns plant roots" means! And will the worms take it in stride?

There are 3,840 tsp in 5 gallons, so 10,000:1 is 0.38 tsp = 3/8 tsp = 2 milliliters in 5 gallons.
Less than 1/2 teaspoon should give you a big bucket that you still DON'T want to get in your eyes!
.
Maybe 100,000 to one would be better, to avoid burning the soil life between the time you pour and the time you water it in: around pH 5 ... but you might need many gallons.
100,000:1 would be 0.2 milliliters (between 1/32 and 1/16 tsp) in 5 gallons.
pH 5 ought to be safe to water with, don't you think?

And always "add acid to water, as you oughter" because that releases heat. If you pour a little water into a jar of acid, the heat rleeases can cause boiling, flinging hot, concentrated water right at your goggles. You are wearing goggles and gloves and a raincoat, right, when diluting acid?

Again - probably the reason no one advises this is that it is dangerous. And maybe it tneds to hurt roots because it delivers such a shock. Best to try it in just one spot, first, in the rain. If that doesn't kill anything noticable, try a larger area.

Corey

Just give your plants a cup of cold coffee once a week and the soil will become acidic enough soon. Work used coffee grounds into the soil weekly or more often if desired. Coffee is also a low nitrogen fertilizer.

My gardenia was suffering this spring. I checked the pH and it was too high. I added an Epsoma sulfur based soil acidifier. It came in a bag with a blue hydrangea on the cover. My potted gardenia has never done better! The leaves are dark shiny green and it is still flowering. I have been checking and adjusting the pH on many plants. (Thank you Santa for the pH tester).

I also read of people putting some vinegar in their water for acid loving plants. I don't know how much to use, maybe a glug of vinegar in your watering can?

I like the chart of pH requirements of vegetable plants. Does anyone know of a similar one for flowering and ornamental plants?