Question 1 for the Week:
Hey HIGH TIMES! Many thanks to your cultivation team for years of helpful tips. Maybe you can shed some light on a question we can’t seem to get a definitive answer on; when growing hydroponically, what is the optimal pH level for your nutrient solution? We have an 8’ x 4’ ebb-n-flow tray that recycles back to the main reservoir and we use Rockwool as our medium.
Clare & Bear, Brooklyn, New York
Answer from Nico:
Hello, Brooklyn! Good news, there is a very clear answer for you here -- your pH in any hydro system should be between 5.6 and 6.4. The grow medium you use will make a big difference in how those levels fluctuate, so make sure you get a decent pH meter and check your nutrient solution daily. Many people take for granted that they need to check their pH levels fairly often, especially in a recirculating system, but you really do. Everyday. Also, remember that the amount of uptake from plants during development will affect your pH level as well as your growroom temps and nutrient solution evaporation rate, though the latter should be very minimal.
Hi, I have four hydro-bubble jugs under a 400-watt MH. I am using Miracle Grow 24-8-16 and my plants are wilting and dying after only two weeks! My lamp is 22” from the tallest plant top and my medium is crushed rocks. Any idea what the problem is?
Jim S., Tennessee
Answer from Nico:
Jim, there may be several problems going on here. The wilting might be caused by water stress, most likely over-watering since you are running heavy hydro in those jugs. Also, nutrient lock-up from your feed solution may play a role. The use of standard Miracle Grow in a hydroponic system is really not an option. Miracle Grow is a synthetic, chemical nutrient that lends itself to salt build-ups and nutrient burn. Miracle Grow is also a very strong fertilizer and is generally known for outdoor, soil-based gardens; even then I wouldn't recommend it for cannabis cultivation (though I believe they may now make a lighter, liquid product for indoor and hydroponic systems, to be fair). However, with an N-P-K ratio (Nitrogen-Phosphorous-Potassium) of 24-8-16 this nutrient is simply too strong for a hydroponic system. A much milder nutrient solution is needed in hydro systems, especially when you have a loose medium such as lava rocks (or crushed rocks) that offer little buffering. During the first two weeks of veg, something on par with a 6-2-4 ratio is better suited for your system. You can’t go wrong with General Hydroponics (GH) or Botanicare if you are looking for ease of use and good results. I’d also recommend switching to an easier (and softer) medium in your DWC system. Rockwool is probably best if you have net pots in the buckets, but HEC (hardened-expanded clay) such as Hydroton would also work well.
Thanks for reading everyone and remember: Grow… And help the world grow, too!
Got questions? Email ‘em over to Nico at Edit.Grow@hightimes.com and be sure to put “Nico’s Nuggets” in the subject line!