Dear Professor Lee,
I over fertilized my plants! I flushed them with 4 gallons of water but that was 24 hours ago. I used a high-nitrogen fertilizer made for sweet corn. I used 25% fertilizer and 75% water thinking it would be fine. Sorry if I bothered you.
Hello Another Lee,
You’re no bother at all! But in terms of your plants, it may be too late. Corn is a nitrogen whore. This is why a lot of farmers prefer to use a slow release nitrogen fertilizer so they don’t have to constantly re-fertilize. Some actually contain weed killer that will kill your weed! Needless to say, agricultural fertilizers are not the best choices for growing cannabis. My favorite is a simple compost tea applied regularly.
A good water flush should be lukewarm and have a single drop of liquid dishwashing detergent added to it. The detergent will break the water tension and allow it to better penetrate the soil. The lukewarm temperature will reduce shock to the plants roots. For good measure, remove as much of the over-fertilized soil as possible before watering. After flushing, replace the soil with a well draining nutrient-free soil mix. Water the new soil to remove any air pockets and keep your fingers crossed.
I had a grow friend that tried to remedy an over fertilization by removing all the soil from the root ball and putting the bare roots in a bucket with plain water that was oxygenated with an aquarium pump. A sort of slapped together deep-water culture system, but it kind of did the trick. A few of his plants did recover and he replanted them. It was a desperate move that salvaged a few of his prized plants. Whatever you try, remember it may work or it might not – that’s the game we play.