Organic nutrient burn?

[Crowdad]

Hi all, I haven't posted in a while so it's time to ask a question: I grow with organic soil in a "just add water" setup. I've found a decent packaged mix of minerals and additives here in Canada which is made in collaboration with the folks at KISS organic in the U.S. I add that to a mix of 1/3 peat moss, 1/3 rice hulls and 1/3 compost. The only issue I'm having is a recurrence of "tip burn" and even the edges getting brown and the tips turning down,( the "claw"). When I consult the Plant Problems page of the website the most likely culprit I find is nutrient burn. I've ruled out light burn because it''s not occurring only at the top of the plants. My question is, I didn't think nutrient burn could happen in an organic, "just add water" scenario. Am I wrong about that?

[AGH]

Hello Crowdad!

I also grow organic which is the only way I've done it. And interestingly enough, you can indeed get nute burn even with organic grows. I know because I was doing an experiment and ended up doing just that this grow!

With organic grows, it's not as easy to overdo the nutrients since, as you are aware, the soil biome kind of balances out how much and how quickly nutrients are taken up by the plant. But that can only do so much, especially with nutrients like Nitrogen. So, if you've ruled out light burn, heat stress, and over/under watering, it is likely that you have some nute burn.

There are a few ways to deal with it. Many synthetic growers will tell you to flush your grow medium and get rid of some of those excess nutes which is exactly what you should do for a synthetic grow. You can do that, but then you're really saturating your soil (organic soil is like a sponge and can hold a ridiculously large quantity of water!) and possibly killing (by drowning) your soil biome which will cause way more problems than a little nute burn.

Since it looks like you're still in veg and it doesn't look like it's horrible (and as long as you've ruled out anything else) my suggestion: let the plant and soil do their thing. Since you still have the soil biome balancing how fast/how many nutrients are being taken in by the plant, it's not like what you sometimes see happening with synthetic grows where it can go really wrong really fast. Keep watering like normal (again as long as you're not over or under watering), keep an eye on the symptoms, and as long as they're not progressing you're all good. Just note that the 'burnt' parts of the leaves will not turn green again, but keep an eye on the new and upper growth to see how they're doing.

And good on you for suspecting nutrient burn! When I first saw mine, I thought it was an Mg deficiency. I did a 2% epsom salt foliar spray and (since it wasn't actually a deficiency) it didn't really get better. But it did stop progressing which was good. Then I saw the downturned claw and that stuck in the back of my mind for a few days because I had seen that in an article somewhere before. Then it hit me! I had added nitrogen 2 times instead of my normal 1 time in veg. Guess what's a giveaway for nitrogen toxicity....DOWNWARD CLAW! (Thanks GWE!!). Thankfully I was lucky enough to have those dots connect before I went on a wild goose chase trying to fix what I thought was an Mg deficiency that was actually a nitrogen toxicity.

My suggestion would be to keep good watering practices and give it a week. My guess is you'll see the burn stop progressing and all new growth will look as it should. Let the fungi and bacteria in the soil do the heavy lifting for you!

[Rwise]

You can certainly get organic soil to hot, just toss in some "green" chicken shit and you'll see it fast. I have made soil to hot several times, 1 batch was so hot nothing would grow in it tests said to use it as fertilizer and scatter it, the grass grew very well.

[Bluey]

Quite true that. And spreaders work amazingly well if moisture content is kept high...but little will grow in it