Growing a bag seed just to experiment with cultivating cannabis, I'm growing indoors under 2 cfl's, 13w day and 20w soft white, with miracle grow organic potting soil. Grow area is a box with reflective foil lining and a 3 gallon pot. Plant is 6 weeks from germination. Seemed to be growing well until 2 days ago, I started getting patches of yello/brown spots on some of the upper leaves. The same day I gave the plant its first feeding and I noticed the spots the next day. I searched a few forums, some seem to say soil ph is off, some say calcium def, magnesium def, but I really have no idea. This is literally my first grow ever so any advice is helpful but I really need directions to fix my poor plant.
You'll need to have a way to test the pH of any liquids going into your plants and they'll need to be adjusted to a pH range of 6.3 to 6.7 before giving to your plants. Continued watering with water out of pH range will lock up the roots of your plants and they can't take in nutrition. You can either use the pH kits with the test strips and pH up and down, or you can order a pH tester meter/stick (if you buy one of these, be smart and buy one that is waterproof and of good quality since the very cheap ones aren't dependable) that you put in the water and it gives you a readout of what your pH levels are. What are your watering habits? Do you allow the plant to dry out almost COMPLTELY before you water again? This is a biggie since they don't like to have their roots sitting in constant moisture. If the container doesn't feel as light as it did when you first loaded it with dry soil, it's not time to water again. They like light and arid soil with good drainage and ease of root growth. If you've only had that plant for a month, it's probably not even got to the point where it needs nutes yet since nutes are meant to be started only after the plant has had a chance to use up the nutrients that came naturally in the soil. When you start a seedling out in a large container of soil, it's going to take it awhile to use up the nutrients naturally in the soil and starting them too soon only fries your plants. But keep this in mind...you judge the overall health of the plant by the new growth. If the new growth is the correct color and the leaves look normal, then your plant is healthy. I can't really tell where this discoloration actually appears on your plant. If it's on the lower growth, it's probably nothing but old leaf die off. If it's happening to the new growth, then you definitely have something going on. TWW
Wow, thank you for all the info. The discoloration in the photo is on growth about two nodes down from the newly forming leaves and is on the large leaf you see, as well as several smaller leaves in the middle, although not nearly as badly as that leaf in the pic. I transplanted into the new pot about 1.5-2 weeks ago, I germed the seeds in a dixie cup. As far as nutrients, I use oc+, crushed into water, 1 tsp to a gallon of water, but didnt have a ph kit, I couldnt find a store near me that sold one, so it is probably a ph inbalance issue, the newest leaves dont have the spots and the leaves just below that have just a few spots. Would you recommend any sort of flush or other action, or should I just lay off the nuts and balance water ph?
