Tomato Seedling Problems

mikerondApril 16, 2014

I started some tomato seeds in Jiffy pellets. Everything sprouted fine and grew a few inches tall. I started them in late January because last year I started them too late, (end of march) I kept them watered and under lights, and used a weak miracle grow solution on them. The problem is over the last few weeks the leaves have become yellow or brown, and the leaves get scrawny stems. and I only have 2 or 3 plants left that look decent. and transplanted them in 3" pots. I am new to seed starting, I get the basics of it, but I have a few questions, when do you remove the seedlings from the heat mat, when do you decrease the length of time the plants spend under the lights? Does any one have experience with these self watering mats kits they sell, do they keep the plants too wet. Any tips to growing tomatos from seed will be greatly appreciated!

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seysonn(8a WA/HZ 1)


Ans: as soon as the seeds emerge/sprout

    Bookmark   April 16, 2014 at 11:42PM
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Since you use peat pellets and I use them too I'll tell you what I do. This breaks so many rules 85% of the people here wouldn't do what I do no way no how.

I germinate in peat pellets after putting the hydrated things in the microwave long enough to raise steam. They go in small trays from cheap frozen dinners that don't go nuts and warp when nuked.

The tray sits over extremely high humidity 75 degree bottom water heat. I flood the tray every single day of it's working life, draining off what doesn't get absorbed within a few seconds.

Before the true leaves even come out, the plants are in full sun. When they "look right", which is hardly big at all, they go into any sort of disposable cup I have, each with a couple of holes made with a hot pokey thingie, with any sort of dirt from a bed that looks like it's compost-y. I leave the netting around the pellet alone since rule number one two and three is never never ever mess with the roots.

That bed dirt gets nuked too. Then the whole shebang goes into the ground eventually, no bothering about bigger cup sizes and fertilizer and lamps and engineered dirt.

Make that 95%, but it works. This year I had four or five un-seedlinged pellets and zero damping off.

Did I mention the fish tank?

    Bookmark   April 17, 2014 at 12:50AM
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There could be many things at play here. You should remove the heat mat as soon as seedlings begin to emerge. I have use 1x1 cell packs with seed starting mix with great success. When the plants have 1 or 2 sets of true leaves, I pot them up to small foam cups. This is probably in week 2 or 3. By week 5 or 6, they are ready to be potted up to a 18oz SOLO cup. I keep my lights on them for 16 hours a day from first emergence to the time they go outside. The fact that your plants are almost 3 months old and are still in the peat pellets and you don't have roots busting out everywhere is your problem. My plants are 6/7 weeks old and the roots have filled the 18oz Solo cups. My guess your plants are dying due to a root issue, most likely due to over watering. If the roots are rotting or have issues, there is no way for the plant to absorb nutrients and the plants will die.

Don't feel isn't as easy as some make it sound and the majority of us(me included) struggle with the same issues. It takes a few seasons to get the hang of it.

Good Luck!

    Bookmark   April 17, 2014 at 9:40AM
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BriAnDaren Ottawa, On Zone 5

Your plants look underfed. How often do you fertilize? I fertilize every time I water.

Check out this site which belongs to Fusion_Power who posts here. It will answer just about all your questions and then some.


    Bookmark   April 17, 2014 at 10:54AM
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There's still time to save the green ones! Transplant them into slightly larger (deeper) containers using soil-less mix and don't over-water them. I wouldn't add fertilizer for the first few days as they will probably suffer some shock from being transplanted.

As for the ones with yellow leaves, I would cut them off at the base and root them. Others won't like this, but I like to root tomatoes in water so that I can see the roots form and know when they are ready to plant in soil.

Good luck and keep us posted.


    Bookmark   April 17, 2014 at 11:13AM
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I kill every plant in Jiffy pellets. I have quite a green thumb for growing in other soiless mixes LOL. Might not be your fault at all.

    Bookmark   April 17, 2014 at 4:30PM
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If you've kept the heat mat on, it's possible they're getting cooked. Definitely try to transplant the green ones like Linda said into 4" pots using a soilless mix. I haven't tried Linda's method for rooting, so can't say. But you will get the hang of it. Personally, I'm not a fan of the pellets. Good luck!

    Bookmark   April 17, 2014 at 8:42PM
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Here's my simple approach.

I also use 72-cell Jiffy pellets. Follow directions about how much water. Heat under pads, about 5-6 days after majority have germinated. Remove pad, place entire tray 2 inches below 16-hour fluorescents. The late ones will come up eventually if you keep each cell watered regularly...not soaked, but moisturized. Once most have
developed 4-6 total leaves, transplant to 100% MG potting
soil with "6 months fertilizer". Ideal room temps 60-70 F.
After 7-8 weeks, will look like heaven. Good luck !

    Bookmark   April 18, 2014 at 10:05AM
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yardenman(z7 MD)

How warm does your heating pad make the water in your trays? If it is over 75, you are cooking them. While tomato seeds germinate at 75 well, the seedling grow best at 60-something.

They don't want serious fertilizer when young. None until a couple inches, 1/2 strength after that, full when you transplant them deeper to larger 3" pots when they are 6" tall.

    Bookmark   April 19, 2014 at 1:33AM
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