ASK THE EXPERTS
What are the ideal parts per million (ppm) for stevia?
Richard Gittings
Dr. Lynette Morgan
Dear Richard,
Unfortunately, there is little technical or research information on growing stevia
hydroponically because it is not a commercial soilless crop; thus, we have no
background of research from which we can draw such technical details. However,
given that Stevia is a succulent herb, it can probably be grown at similar ppm
levels to other hydroponic herbs. However, I would recommend that anyone
growing it should carry out some trials to see which ppm level suits the plant.
Generally, plants are grown on a more dilute solution from the seedling stage to
when they’re planted out into a hydroponic system. Around 400 to 600 ppm in
this stage and 750 to 840 ppm in the grow-out phase should be fine. Also, use the
lower end of that range under hot conditions and the higher end in winter to
maintain the quality of the foliage.
Kind Regards,
Dr. Lynette Morgan
What does it mean when the plant's leaves have dots and brown
stains on them?
Messod Ifrah
Matt LeBannister
22
Maximum Yield USA | September 2012
There could be a number of causes
and these are the most likely:
First, insect damage can leave spots on
the leaves. Buy a sticky card, and leave
it for a couple days to see if any insects
get stuck.
Secondly, it could be a potassium deficiency. Are the leaves curling, and are
these curling leaves older? If so, flush the
growing medium with lots of water and
add more potassium, and start checking
pH more often.
Third, it could be a disease called bacteria spot. Is there a yellow ring around the
brown spot? If so, destroy the badly infected
plants and sterilize your tools to prevent reoccurrence.
Finally, it could be caused by foliar feeding plants when the light is too hot. Be
sure to spray leaves 10 to 15 minutes before lights go off.
Hope this helps,
Matt LeBannister