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Is this the seedling phosphorus issue?

Posted by wyattdog 5 (My Page) on
Thu, Mar 29, 12 at 12:18

Do these tomato and pepper seedling have problems with phosphorus?

I have had this problem for several years now. My tomato and pepper seedlings turn a purplish color and just look as if they don't flourish while they are growing. They always perk up when I plant them outside, but I always wonder if this issue has caused developmental delays.

These were planted on March 9. I try to grow my plants organically.

This year, I used Pro-Mix Organic Mix to start the seedlings. I have them on heating cable: cable is tied to hardware wire, and aluminum sheet is placed on top (the cable cycles on and off as needed). I read in previous posts that heat might be a problem which cause them to turn purple so I have kept them on this set up without turning off the cable. I checked the temps this morning and the air temp near the seedlings was about 72 and the soil was about 72.

This year I have kept lights on 24 hours. In previous years I had been turning them off 8 hours at night so I thought I would try something different to see if that helped. Apparently it doesn't help with this problem.

I know it's about time to re-pot the seedlings. What is the best growing medium for this? Would the Pro-Mix work? Usually I use a diluted fish emulsion to fertilize when I transplant. This seems to go along with what others recommend.

I have this dream that someday I will have beautiful green healthy looking seedlings that I grow in my basement. I think I try to do what's recommended in the forums, but somewhere I'm missing the mark. So how does one correct the phosphorus issue?

Any recommendations would be appreciated. Thanks! (Sorry the pics are large - I'm still learning.)




Follow-Up Postings:

RE: Is this the seedling phosphorus issue?

Unless you raised the light for the photo, it should be much closer to the plants. The medium looks too wet, and bottom heat should be removed as soon as the seeds germinate. Fertilizing is not recommended until seedlings have their first set of true leaves.
Separate the seedlings into their own containers, plant the leggy ones as deep as you can, go easy on the watering and get that light right down on top of them.
My own experience with the phosphorus issue is that it has been transient and has corrected itself as the plants mature, unless the temps are quite cold for a long spell. I'm usually not concerned about it with seedlings. JMO

RE: Is this the seedling phosphorus issue?

Yes that is the issue and yes it will go away all on its own as the plant matures. I agree with noinwi - cut the watering, lower the light - they are leggy already - and don't worry about the purple coloring.


RE: Is this the seedling phosphorus issue?

I've also been experiencing this problem with both my tomato and pepper seedlings. My room temp is approx 75/76F but my soil temps are much lower in the mid 60's most likely due to the fact that evaporation cools the soil. As much as I would like to leave it be, I feel as though I should be doing something about it. I've read that warmer soil temps would rectify the problem and allow for more P absorption. My bhut jolokia plant is about 1.5 months old and although it's starting on it it's 3rd set of true leaves it's only 1.5inches high. The stem is deep purple and the older leaves are a bit purple with the new ones showing purple veins. I feel as though I'm stunting it and I'd like to do something. Any suggestions would be great.

Currently have it under two-54w 6400K fluorescents on a 16/8 schedule. Distance from bulbs is approx 4-5 inches. I turn on a fan every once in a while to get some circulation.

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