What To Do If You Over Fertilize Your Plants

If you know you have acute (very serious symptoms) of over fertilization (nutrient surplus) you need to act fast to save your plant. If you are growing hydroponically, empty the reservoir and start over. You may want to flush the medium once before refilling the reservoir. Read on for soil and soilless mixtures.

First, leach the grow medium. Leaching means you basically flush or run water through the mixture. Nutrients will be carried by the water and into the tray you use to catch water over flow. You should water your plants until it runs out the bottom into the trays. You will need to empty the trays a few times, so it is a good idea to have a spare tray to put the plant in when you empty the tray. (The plant will continue to drip out water so you want to have a second tray to put the plant in to keep down on the mess).

I use tap water, but you can leach the growing medium with a professional leaching agent to leach away metals, calcium, sodium, chlorides and other compounds, which can build up in the growing media. This leaching agent will bind to the nutrients and a good one will help remove nutrients that are not water soluble. Check the HTGSupply.com website for specific products.

Second, you need to check the pH if you are using a soilless mixture. Overwatering and leaching of nutrients will affect pH. If you are using soil this won’t be such a problem. Adjust the pH to the proper range for your plant.

Third, I would then administer a beneficial product like stump tea to the soil. The microorganisms will help to bring to balance any remaining nutrients and those lacking due to leaching. You could also use a high quality vitamin B-1 product such as Superthrive (1 drop per gallon). If your plants have been in the medium for a few weeks, you should also use a ¼ strength organic fertilizer to supply some nutrients for a week or two. Once you see good grow again increase to the manufactures recommended strength fertilizer.

You also may want to reduce the light intensity for a few days. If you are using an HID or LED you may want to raise the light a bit. Most indoor growers have the lights as close as possible to the plants to maximize absorption. But if you over fertilized your plants, they are stressed so reduce the light intensity and let the plants recover. Or, if it is not a hassle use fluorescents about 1” from the plant tops for a few days. The low output but excellent light frequencies provided by fluorescents are easy on plants.
You won’t see results instantly, it will be days. But you should see new growth lacking the symptoms.
Perhaps most important, write down how this problem happened and take steps so that it does not happen again.
Good Growing,
Dr. E.R. Myers


hillbilly said...

lucky for me, jarrett and kevin at the htg supply store in PA urged me to be sure to keep the best DAILY log i can so when things go wrong, i would stand some chance of being able to ACCURATELY correct them. this single piece of advice offered to me has been the key to my actual horticultural LEARNING. for me, this post has been one of THE MOST HELPFUL writings i have seen yet. the links in the body of the text enable me to use this blog like my own personal consultant. i was reluctant to participate (as i only have 1.5 years or so of experience) in any posting in an effort to not add to the barrage of multi topic questions fired away. THIS blog is well represented by the good dr.'s statement: "This is a positive place where ideas are observations are shared to help everyone be a better grower." A LOT of the blogs i have visited and posted on seem to fall WAY short of providing (me, anyway) any REAL help at all. htg supply is 100% top shelf in all they do (in my opinion), because their claims hold true. how refreshing it is to see a business interested in ACTUALLY helping their customers. dr. meyers - thank you for your forward thinking efforts.

hillbilly said...

i keep the 400 watt hps fixtures i use 16 - 18 inches above the canopy, and i monitor the temp at the canopy with a growbright hygro-thermometer and keep the temp NO HIGHER than 80 degrees farenheit (from htg supply, of course - for the best price i can find ANYWHERE) - what distance would you recommend i raise the lights? does 20 - 22 inches sound reasonable to you, considering the inverse square law on these artificial light sources? after reading this post, i feel like i should have come to the conclusion of raising the ligts on my own - thanks again Dr. Myers!