Two of the biggest beginner mistakes that happen when growing marijuana for the first time are over watering and over fertilizing cannabis.
In this article, we will be going over the symptoms and cures for over fertilized marijuana plants. It’s nothing to be ashamed of, or to even throw your plants out over.
A little bit of knowledge on the subject will help prevent killing your plants with too much marijuana fertilizer.
Of course, the best way to prevent an over fertilized cannabis plant is to have a simple and easy to follow fertilizer feeding schedule like with Reefertilizer cannabis nutrients.
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When I had my first grow, I grew from seeds I found online through Seedsman. When the first set of leaves appeared, I was very excited.
The sprouts grew quickly and I wanted the best for my little marijuana plants so I decided they were old enough to start feeding fertilizer.
I made a mix of grow/veg fertilizer and fed my plants twice a week when their pots were dry. By following the instructions on the package of fertilizer, I thought I was in the clear.
My sprouts looked great after a few weeks of feeding them. Then all of the sudden, the tips went brown, leaves decayed and my beautiful young plants were now very sad looking.
It’s common for fertilizer brands to recommend larger feeding and sell more fertilizer. This was one of my pet peeves which we fixed with Reefertilizer. The dosages for Grow and Bloom are more conservative, which saves your plants and you money.
How To Save Over Fertilized Cannabis Plants Step by Step
- Flush your soil with fresh clean water. Use at least the same volume of your planter.
- Wait 15 minutes and flush with the same amount of water.
- Give your plant a week to recover.
- Start feeding cannabis nutrients again.
This method works best in soil and coco when using synthetic fertilizers like Reefertilizer Grow and Bloom. If your using slow release or organics then you may have to transplant into clean soil.
How I over fertilized my cannabis plants
The mistake I made was fertilizing my plants way too early and giving them too much fertilizer. A marijuana seed might not look like it, but contains a stockpile of energy to start the first stage of growth. One good seed, good soil, water, and a good light source is all a plant needs to get to the vegetative stage.
Seedlings in soil don’t need fertilizer immediately, their first set of leaves (cotyledons) are full of the essential nutrients for the first phase of growth. Also, the soil itself should contain nutrients that your seedling can make use of. If you’re using a soilless mix like coco coir or rockwool, they would benefit from a diluted dose of fertilizer.
RELATED: The 411 on Cannabis Seed Germination
What happened with my little gals was that the sprout grew while the soil became toxic, filled with too much fertilizer. Eventually, the soil was so hot with fertilizer my plants burnt; figuratively of course.
I was feeding them way too early, I should have waited until they were a little bigger (3-4 nodes) before giving them a proper dose of nutrients.
I was also feeding them twice a week. There was no way a plant that small could absorb that many nutrients.
A buildup of fertilizer will damage a cannabis plan and potentially kill it. Always be careful when you’re first adding marijuana fertilizer. Waiting until the plant is 5-6 inches tall or has 3-4 nodes before feeding them marijuana fertilizer. Nitrogen is the most essential nutrient for marijuana plants and the most common deficiency for cannabis. Lower fan leaves will begin to turn yellow when nitrogen levels are low or when a bad pH is blocking the plants from nutrients.
What Happens When You Over Fertilizer Weed?
When too much fertilizer is added to cannabis, the plant can become overwhelmed by the excess nutrients. This happens because a cannabis plant can only absorb and use a certain amount of food at any given time, much like a pot can hold a certain amount of water before it overflows.
Here’s what’s happening inside the plant:
Excess Salts: Over-fertilization leads to an accumulation of salts, which can draw out moisture from the plant’s root system and leaves, causing dehydration and a burned appearance on the leaves.
Nutrient Imbalance: An overabundance of certain nutrients, like nitrogen and potassium, can become harmful. Too much nitrogen causes the leaves to darken and curl downwards, a condition often referred to as “the claw”. Too much potassium can lead to brown spots and burnt edges on the leaves.
Root Stress: The roots of a cannabis plant can be damaged by high nutrient concentrations, impairing their function. This damage can inhibit water and nutrient uptake, leading to stressed plants with burned leaves.
In this state, the plant’s growth can be stunted, affecting the overall health and eventual yields. Taking action against over fertilization is key to helping your plants recover and thrive.
Flushing Over Fertilized Marijuana Plants
I felt like I had betrayed my little plant and wasn’t sure what to do now. So I went and looked for resources on saving over-fertilized marijuana.
The first thing recommended was flushing your plant. This involves giving your plants a very large amount of water.
This water will flush out the excess nutrients in the soil. You will need to a quantity of water that is equal to at least 2 to 3 times the volume of your planter. If you’re flushing a plant in a 5 gallon pot, use 10 to 15 gallons of water. Soilless potting mixes will require less water for flushing.
If the problem isn’t too severe, the plant will start looking healthy again in a day or two. The damaged leaves might not grow back but new leaves should start growing healthy and green.
My plant didn’t bounce back right away so I decided it might be in my best interest to re-pot (transplant) it into some fresh soil.
Transplanting Over Fertilized Marijuana Plants
I decided to transplant the marijuana plant to a larger pot with good clean soil. The root system was substantial and packed tightly so transplanting was easy. I used the pot itself to make the correct size hole to transplant into.
Being very careful I moved the little guy into the larger container
A few days later after watering with good clean pH balanced water, it returned to being lush and green. The underdeveloped leaves at the nodes grew new fan leaves, but a few dying leaves remained.
The plant had gone from brown and black to bright beautiful green again.
This plant has lost a lot of time from being stunted. it will take time before it starts growing at full speed again.
Over Fertilized Cannabis Plants in The Flowering Stage
It’s never good to over fertilize your plants and it’s even worse to do so in the flowering period. The toxic build up will stunt the growth of buds.
If you happen to over fertilize your plants in the flowering phase you can fix it the same way by flushing the soil.
You will want to start giving it flowering fertilizer as soon as it bounces back. A week is usually enough time in most scenarios.
Keep in mind the cannabis plant will naturally get a little brown and crispy leading up to harvest. This is completely normal as the plant is focused on the nutrient requirements of the flower only.
How To Prevent Over Fertilizing Your Cannabis
Keep track of the level of nutrients you’re feeding your plants. A grow journal can be a helpful tool for all growers.
Reefertilizer cannabis nutrients are crafted for each phase of growth. You can rest assured your plants will be getting the correct levels of essential nutrients.
Start low and slow when it comes to nutrients. If you see the signs of over fertilization, flush your plants and continue the recommended feeding schedule.
We are all beginners at some point or another and mistakes happen. As long as your trying to give your plants the best you can, they will repay you in the long run. It takes time to master the art of growing marijuana.
Looking for advice from other growers is amazingly helpful, Join us on our facebook page and connect with other cannabis growers.
If you have any ideas of what you would like me to cover or other tips about helping over fertilized marijuana plants, please leave a comment below. Happy Growing!
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Mike Drouin is the co-founder of Reefertilizer. He’s an experienced craft cannabis grower and a writer of many articles regarding the process. Mike lives on Vancouver Island and enjoys cycling and camping and will sometimes combine the two.
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