SO2 Damaged Impatiens and Begonias

[1voyager1]

It is hard to find advice on the care of these ornamentals in a sub tropical climate. So, I'll try my questions here.

Impatiens -
I have been just letting a planting of orange impatiens do what ever it wants to.
Now that it has lost all its leaves and flowers to the SO2, I'm thinking of pruning it back to let it start over.
Right back to ground level, or...?

Pretty much the same question for the Begonias.
we planted a bunch of these late last summer.
They have become very leggy with little foliage and flowers.
Now they have NO foliage or flowers thanks to the SO2.
Prune them back to the ground or ...?

[dan d]

Prune and hope

Dan D
HPP

[kalianna]

Take them down to just above the first join, leaving the join intact, usually a few inches above ground. I tested our water, overflow from catchment + rain and it was way acidic. I added about 2 T of baking soda to 25 gallons of way and that brings it back to neutral. Prune first and then water with the neutralized solution. Also test your soil but in lieu of that, make sure to water the ground around the plants too. If it continues to deteriorate try adding some dolomite to the soil. And if there's gas when it rains, try covering them if you can, Same advice for both impatiens and begonias. Please post what ultimately happens.

edited to make clearer

[1voyager1]

I added a couple of heaping cups full of bicarb to our 10k catchment water during the last heavy rain.
I add it at the top of the rainleaders and let the roof runoff wash it down into the tank.

M'Lady says she can feel it in the water.
I'll check pH with the spa kit tomorrow.
If acidity isn't too high, I'll prune them back and use it on them.

Plus, you've reminded me that I need to get more dolomite.
I used almost all I had on the citrus, bananas, avos, etc. just before the fun began.
That may have been a fortunate timing for the application.
Yeah, I'll go to Pahoa feed and grab another bag.
None of the fruit trees seem to be reacting badly.
The avos have been dropping a lot of older leaves.
But, this is the time of year for them to do so.

EDIT:
Just checked the pH of the catchment water.
It's acidity is beyond what the spa water, kit can measure.
I've added another heaping cup full of bicarb to the top of a rainleader and am running a hose into it.
That should mix it into the tank quicker, and as far as the pressure tank too.
I'll continue to let the water run and check pH every so often and add bicarb until it nears neutral.

REEDIT:
I've put 4 heaping cup of bicarb into the catchment tank through today.
A heaping cup has to be close to 1-3/4 cups.
I've put something on the order of at least 6 to 7 cups of bicarb into it.
The pH measurement reaction is taking place at a slower rate but is still too low for the kit to record, 6.8.
It is also probable that I've added the bicarb too much too quickly.
The reaction may be still ongoing.
I'm going to let it sit until tomorrow morning, then check it.

[kalianna]

It took 3 x 1 lb. boxes of baking soda to get Ph back to normal in our 12000 gal. tank.

ETA: Yes, it took overnight for the bicarb to fully react.