I started these tomatoes on February 5th inside a humidity dome with a heat mat. They sprouted incredibly quickly within 3-4 days and I moved them off the heat mat and onto my shelf with grow lights.
However, they have not grown much at all since then, only a couple are growing any true leaves but they are incredibly small and most of them are not growing true leaves at all. Some of the cotyledon leaves are turning yellow and falling off.
Grow medium: coco coir, rinsed and salt free, with vermiculite and perlite
I water as needed when the soil is dry and the tray is not heavy to pick up. I bottom water and let the trays soak up water and dump out any extra. I top water with a squeeze bottle if one square is drier than the rest.
The grow lights are full spectrum LED and are placed far enough away per the manufacturer’s instructions. I have checked the PPFD with a par meter and confirmed the seedlings are receiving plenty of light.
16 hours of light on / 8 hours off
An oscillating fan blows gently on the seedlings for 16 hours.
The temperature in the room is 70-75 degrees depending on the weather outside.
I have no idea what else could be wrong and I have literally tried so hard to make sure the environment is perfect to grow and yet they are not getting bigger at all. I’m at a loss for what to do next.
I transplanted one row into larger trays to see if that made any difference and it did not. I even tried a diluted liquid fertilizer to see if they would speed up and that did not work either.
Is there something I am missing?
by TastyKick551
23 Comments
That light setup seems awfully far away from the seedlings. I’d either lower the lights or put something underneath the trays to get them closer to the light source.
Are your grow lights always that far from the seedlings? I don’t grow indoors but my understanding was that the lights should be a couple inches above the plants and you move it up as they grow. Seems like they have maybe had very little light since they sprouted. They look kind of leggy to me.
My guess would still be that they’re starving, unless you’ve been regularly feeding them with fertilizer. I’ve had this experience before with some soils, after repotting to proper nutritional soil they picked up super fast.
I’m looking at my seedlings that have remained the same for 10 days and was also getting concerned, but checked the bottom of the pot and roots are peeking out. I think they were simply working on roots. I’ll start to properly feed them now, hope they’ll get on with growing the tops.
ETA: they look a bit leggy, move them closer to light as well.
Those babies need more light, they’re stretching for it. I’m not familiar with “pro” grow lights as I use led shop lights but I can’t imagine those are so strong that they are giving enough light that far away. My lights start out just a few inches above the seedlings when they’re first germinating. If those are peppers on the side, see how the ones at the edge are leaning sideways, trying to get more light? That’s the only thing I can think of here because it sounds like you’re doing everything else right. If it was me, I would drop the lights down low and see what happens, if they’re not responding quickly I would restart a new batch with the lights down low, if they get too stunted when they’re tiny it can be really hard for them to bounce back and a month is a long time to be without any true leaves, it might be better to cut your losses.
Those trays look very small for tomatoes. Where do expect the roots to go? And why more than one per cell?
I started mine in solo cups on February 9th and had almost 100% germination. I thinned any extras and all are now 6″ tall or more, and the roots are pushing out of the cup. I’ll transplant into gallons over the next 2-3 weeks.
They’re starving. A seed usually has enough energy and nutrients to build the cotyledones, but then need light and nutrients to grow further. Rinsed coco coir + vermiculite + perlite does not provide N, K, P, etc.
I recommend to plant those seedlings in real soil and bigger pots, and only one per pot. You could also plant them a bit deeper to get rid of the leggyness. Then raise them a bit to get closer to the light and you should be fine.
Man. This is a tough one. I pride myself at being pretty good at diagnosing things (having made countless mistakes of all kinds myself over the years), and it seems like you have covered all the usual bases.
So I am going to throw out some random things to see if anything resonates.
1) There is something wrong with your soil medium. I do my starts in peat pellets. During the pandemic, I could not find my usual brand. I did find some, but those plants did terrible, and looked lot like yours. I usually do my starts in three batches a couple weeks apart. Before I did the last batch I found a box of my usual brand I had in storage and I used them. The plants popped up and did great. There was something wrong with the original peat pellets (maybe it was pH? See #2). I gently removed as much as I could and potted them up with good soil, even though they were way too small. Eventually, they recovered, but my starts were very behind.
2) Nutrient lock out. I haven’t had this happen to me, but if the pH is off the plants can’t absorb some nutrients. You are using coir, which does not have a lot of buffering capacity. It could be the pH of your starting mix is way low. You could try getting some pH up used for hydroponics and mix a very small amount in with your water for a few days. Then, try more liquid fertilizer.
3) They got too hot and shut down. This was from last year. I do my starts in a closet in my basement that holds our gas furnace and hot water heater. We went away for the weekend, and my teenage kid was watering them for me. I keep the closet door open when I have plants going else they get too hot. My kid closed the door and it was a cold weekend so the furnace was on a lot. They were at about the same stage as yours, and the temps were probably 95⁰+ for 36 hours. They didn’t die, but they “got stuck” and basically looked like yours for a couple weeks. They recovered, eventually.
4) A few years ago, I switched to LED lights to replace florescent shop lights. Turns out the light was too intense for the newly emerged plants. I also checked the intensity and thought things were good, but the plants didn’t do well until I moved the lights back a few inches. That was all it took. Now, once the seeds germinate, I keep them in the humidity dome for a few days to help them adjust to the artificial light.
Sorry I can’t be more helpful! The good news is that in all cases where I had similar issues, my plants did recover.
This seems to be a reoccurring theme with those seed starting soils that are void of nutrients. They are based around water retention with little to no nutrient content. I’m assuming you have to have a regular fertilizing schedule in place in order to grow your seedlings.
Next time 1 seed each square
And start feeding 25% nutrient solution after they pop
That grow light isn’t great and it’s too far away. And there is more than one growing in the same pod in some cases.
they are starving as the soil mix doesn’t provide any nutrients.
Feed asap with some liquid complete fertiliser, half strength or as specified by the manufacturer.
Always add some nutrients to the mix, i use fish blood and bone or worm castings
Are you using any nutrients at all? Coir, perlite and vermiculite are inert media. Once the cotyledons start to yellow, the seedlings need low level nutrient supplementation to match the light input.
What is “plenty of light”? 250-300 ppfd?
ETA: your environment parameters sound good. Cell size is a little small. Double sowing is fine but you need to cull them early so they don’t compete for root space. Two seedlings in the same pot will literally dwarf both plants by 50% after several weeks of growth.
Lights are WAY too far away
I too use my own mix of coco coir (buffered), perlite, compost, sand, bio char, worm castings, and peat for my indoor vegetables, but start with just a good seed starting mix when they are in trays. I reccomend:
1. Download the Photone app on your phone and see how much ppfd the seedlings are getting at that distance from the light. I’m guessing you need to make adjustments.
2. On your next starts, try switching to a medium that has more nutes in it to sustain the seedlings a few weeks after germinating. Tomatoes germinate quickly, but if you grow peppers or anything else that has a longer germ time, this will help.
3. Go through and cherry pick the best out of what you have here and up pot them to a 3” pot or solo cup even though they aren’t technically ready yet, make your light and pH adjustments, and they’ll probably be fine.
I had a very similar problem two years ago. It turned out the soil I used was lacking phosphorous I think. Maybe try a diluted all purpose fertilizer. Don’t make it too strong since they are just babies. When I did that, my seedlings started growing again, so I only lost the two weeks where I didn’t realize they stopped growing.
Not close enough to the light.
Started Feb 9.
https://preview.redd.it/tbictqki9dme1.jpeg?width=3000&format=pjpg&auto=webp&s=d1d473198b5c35f2057f5f8bee7db7cbf811af7d
The light is too high up
A couple of things I always start tomatoes in a smaller cell, then separate and upon burring the stem right up to true leaves.
At this phase after I up pot I use a 2:1 fertilizer and only give half perscripted amount but to feed them a bit extra nutrients
Puzzling! It sounds like you are doing everything right!
You’re making this too difficult on yourself.
Just grab some ordinary Miracle Gro potting mix (NOT the “moisture control” version, NOT the “seed starting mix”) and use that as your seed starting mix. I’ve never had that fail. It feeds the seedlings well for at least 3 weeks, and doesn’t get too waterlogged, doesn’t dry up too quickly.
And then put your lights closer to the seedlings, or turn up the intensity. Yours are very leggy, reaching for the light.
They’re leggy, which means they’re not getting enough light. I would add the mat back underneath- those make a huge difference! Also you could add a little liquid fertilizer just to really get them going.
This happened to me two years in a row after having no problems with starting seeds years prior. Turns out it was my soil which was bad. Got new soil and have happily had no problems since.