I seem to be killing my lettuce seedlings!

stevey_fracJanuary 19, 2010

Hi Guys, I'm looking for some advice. I'm clearly doing something wrong.

I'm trying to grow some lettuce, for latter transplantation into a hydroponic system inside. Mostly for fun but I do plant on eating my just reward in the form of salad later.

I planted 8 seeds in rockwool starter cubes. I soaked the cubes in water for a while, with a bit of vinegar to bring down the pH a bit. 3 days later, all 8 seeds sprout and show decent growth. They were under a 400w metal halide bulb. I watered them every day with a weak nutrient solution and left them under a plastic dome for a few days, the removed the dome. They stayed pretty moist the whole time. A week later they are dead and dying. Some fell over. The leaves started to yellow. Secondary leaves never appeared. I pulled one sprout that was pretty much toast, and the root was pretty well developed, but about the last cm or so was going black.

What am I doing wrong here?



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Belgianpup(Wa/Zone 7b)

Usually, the dome is just used to prevent the growing medium from drying out and for keeping the seeds warm. As soon as the seeds sprout, remove the dome completely.

Yellow leaves in young plants are often a sign of too much moisture. Young plants falling over at the 'soil' level is often a sign of a fungal problem called 'damping off'.


    Bookmark   January 20, 2010 at 12:29AM
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If the last centimeter of root was black then it is a fungus and probably cause by overwatering. Seedlings do not need fertilizer until they get growing well and have a couple of sets of true leaves.

I agree completely with gardengal. The humidity cover is for sprouting seeds and should be removed after sprouting. Plants need good air circulation to prevent damp off.

I have never grown seed hydrophonicly so maybe you need an expert in they way to do it.

    Bookmark   January 20, 2010 at 5:47AM
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Ok. Removing the dome then!

At this point, hydroponic seed starting and regular seed starting are much the same I think. Your grow it in soil, I grow it in a soil substitutes, but I think the mechanics of germination and such are the same.

    Bookmark   January 20, 2010 at 11:06AM
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This fungus you guys talked about. Will it spread to neighboring areas?

I planted a new batch of lettuce on saturday and nothing has come up at all. Last time everything sprouted within 2 days.

    Bookmark   January 21, 2010 at 3:44PM
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Ok, I threw everything out, sterilized everything with a 1:3 solution of bleach for about 30 minutes and started over.

Here's hoping it.. like.. works this time :)

    Bookmark   January 21, 2010 at 11:28PM
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Stevey I never use the dome. I plant lettuce right on top sprinkle a tad of fine vermiculite or perlite over the seeds Spray with a fine mist and you should be good to go. You can just bottom water after that Don't go over 80 F And most lettuce needs light to germinate. Do you have air circulation around the started plants? I use a small fan, but I don't blow it right on the plants just indirect air movement. OH one more thing If you have romaine lettuce it will not need light to germinate, but still should be started below 80 F.

Curt :-)

    Bookmark   January 22, 2010 at 12:26AM
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It's salad bowl loose leaf lettuce that i'm growing. The dome is only going to stay on this time until such time as the lettuce sprouts. The tomato and pepper, basil and dill are on their own after that... I think.

From this point on, I'm only going to bottom water all the plants, having learned (i hope) my lesson after making my last batch sick.

    Bookmark   January 22, 2010 at 10:14AM
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