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This is a La Rosa Roma tomato that is about 4 wks along. On several of my tomato plants I have noticed a whitish hue developing on some of the leaves. These plants are grown under full spectrum lighting placed 2 inches above the height of the plants. They are watered through capillary mats. The only thing I have sprayed on the plants themselves is a diluted hydrogen peroxide solution to stave off fungal infections. I have started to feed the plants a very diluted miracle grow solution and will alternate feedings with a worm casting dilution. I can't figure if this is typical of the plant or if there is something wrong with them. It does not appear to be fungal or powdery mildew because it does not rub off.
I have also noticed on several flower plants a lightening around the edges of the leaves which seem to curl somewhat. Are they being burned by the fertilizer?
Anyone have any clues?
Hi BradshawBunch,
Let me start by saying I am no means an expert, but I can tender my own opinion if nothing else, to keep you going until the experts do show up.
First, let me ask you about your lights. Are they the heat-producing "grow light" kind, or are they full-spectrum fluorescent tubes? I haven't ever used the "grow light" kind, but I understand they produce a lot of heat, and what you're seeing looks a LOT like the sunburn damage I've gotten when leaves get too hot. I know the cooler (temperature-wise) fluorescent tubes you want to keep 2" away from the leaves, but if your bulbs produce significant heat, that's probably going to be way too close.
Second, I think your curling, burned-edged leaves might very well be from too much fertilizer. Carolyn Male, a tomato guru and our resident expert, strongly advises against fertilizing until plants go into the garden, because of the damage that can happen to new and tender roots. Other people disagree, and feed maybe once with very dilute fertilizer (MG or fish emulsion for the organically-inclined), but I think the consensus is that you don't want to do that more than once before planting out. The plants are still running on nutrients from the seed and shouldn't need much at all.
OH WAIT, I just re-read your post and realized the fertilizer question pertained to flowers, not tomatoes. Can't help you at all there, sorry...
Thanks for the response! Yes my lights are flourescent full spectrum and not considered "grow lights" per se. I don't think they give off much heat. Not much that I have noticed anyway. Besides, I'd rather move the lights a little higher than for there to be some disease process going on. I will try moving the lights higher and see if that doesn't prevent others from getting like this one. I think I have three out of about 12 that seem to have this problem. Not all are the tallest either. But we'll give it a whirl.
Yep, looks like they're scorched from the lights to me too. I moved some of my plants outside last week and left them in the bright sun too long. They got sunburned on the top leaves and look just like that.
I would say you are also offering too much feeding at this early stage, especially indoors plantings, the best time to start feeding tomatoes and flowering plants is late spring when the winter rest period has passed and the plants are coming out of there dormant season, for my tomato's, I dont start to give any food till at least one or two sets of flowers have arrived, then very weak solution, then as more flowers develop, move onto full dosage once per week.
As you are already going to lift up the lights then I would think that will help, but also as you are using a capillary mat system for watering, I would remove a few plants from the pots gently, and just check that the compost is actually getting enough water to the roots,
I use this system a lot, and you cant always rely on the compost in all pots reaching the mats, so it will be worth a check, it is easier to add extra water than try to remove it, also remember there is a certain amount of this water lost to the atmosphere with mats.
the plant in the picture also looks like it is ready for some form of support as it has keeled over a bit, so make sure the lights are not making the plants too leggy, I know some folks only run the lights for so many hours per day, so check this out also. good luck. WeeNel.
