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stage_rat

Nutrient deficiency in my seedlings?

stage_rat
18 years ago

I have seedlings that are one month old and younger. I have fluorescent shop lights as well as a MH 1000-watt grow light. I realized when potting-up that the older seedlings, which have been under the incandescent, are much paler than the seedlings living under the fluorescents. The old guys are a very yellow-green, and the young ones are deep green, with purplish stems. I even have some of the leaves on the older seedlings showing green veining and yellowing, crispy edges on the older leaves.

From looking at the problem-solver I THINK this would be due to iron or magnesium deficiency, which I should be able to correct. This didn't occur last year, and I am using the same unfertilized potting mix and fertilizer (fish emulsion). Perhaps I haven't fertilized enough. The fish emulsion doesn't have any secondary or micronutrients, so I plan to add a little slow-release plant food to each plant.

I don't think I have overwatered, although I don't let the mix get completely dry, since that makes it so unabsorbent. Also, I did start to harden 2 days ago, putting the plants out in midday sun for 15 minutes. I think that might account for some crispy edges, but there are none on the younger, darker seedlings.

I'd really appreciate it if anyone can comment on whether fertilizing will solve my problem, or if it may be something else.

Thanks!

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