Question
Hi again Darlene;
Could you give me a quick course on pH and correcting pH, for
the following plant types; cactus, succulents, crotons, and
diefenbachia.  Could you please tell me what pH each type likes
and how to correct an improper pH.
Also I have been using a diluted 20-20-20 on all types -
probablly wrong. please advise the proper fertilizer numbers and
how often.
Enough questions for now.
Thanx in advance
Peter
nice to see you back online again. U.S. thanksgiving?

Answer
Peter,

The plants you inquired about and most houseplants require a PH of around 7 which is neutral. A few plants, azaleas, Norfolk Island Pine, gardenias, anthurium, Boston ferns and African violets require a PH that is more acidic, between 5 and 6.

The 20-20-20 fertilizer should be fine as long as you are following the directions on the package for dilution or you are diluting it even more. Over fertilizing can cause yellowing leaves if that is what your problem is.

All the plants you mentioned are very sensitive to overwatering. They need to be bone dry for a few days before watering again. For those plants I would highly reccommend a moisture meter that has a probe that you can insert in the soil to find out the moisture level in the root zone. In my area they cost $10.00 -$15.00. The meter needs to read dry in the root zone before you water those plants again.

The following web article on houseplant care is excellent:

http://www.allsands.com/Gardening/indoorplantcar_wow_gn.htm

Yes, I was out of town for Thanksgiving, visiting friends near Milwaukee, WI.

If you have more questions feel free to write again. Good luck.

Darlene