Tomato Seedlings

[acemaker]

Hello all. I am new here as well as a first time seeds to plant tomato grower. Last year I saved seeds and planted them. They are now three weeks old and some are doing great while others are not. I followed the instructions with lights, heating pad, etc. In the pictures attached you will see some in peat pots and some in plastic cups. The ones in plastic cups had the cheapest potting soil I could find (at Dollar Tree) and they are growing great. The ones in the peat pots are scrawny and not growing well. I water them all at the same time. The ones in the plastic cups were on the 'outskirts' of the grow light, yet they seem to be doing much better.

I am thinking I had the a) light too close to the peat pots or b) the peat post retain too much water.

Can anyone help me out here? Many thanks in advance.

[HL2601]

Are they the same varieties?
Be super careful about watering all the time. Tomatoes prefer a deep watering when close to dry rather than many mini waterings!

[acemaker]

Thanks for the information on watering. Yes, they are all the same. I saved the seeds from one tomato from the previous year.

[SeanInVa]

Does the cheap potting mix from the dollar store contain any fertilizer in it? The peat pellets don't, as far as I am aware.

What kind of lights are you using? If the lights are too much, you will likely see light burn (sun scald), but I don't see any evidence of that from the pictures.

Additionally, if the lights are too weak, plants will streeeeetch towards them.

I do agree though, based on the pictures, the plants in the peat pellets do seem rather stunted

[acemaker]

I doubt the cheap potting soil had any fertilizer in it....it was very clumpy when I got it. I was not aware that the peat pellets don't have any. That is good information to have.

For lighting I am using the set up shown in the picture. At first I kept it as close to 2" away from the plants that I could. It was recommended by one of the youtube channels. Does the sun scald make the plants slightly brownish? I do think that the smaller plants are starting to become more green today, but a way darker green than the bigger ones.

And yes, the plants on the far end of the light are stretching I think (see picture).

Again many thanks....this is my first 'seeds to plants' attempt ever.

[SeanInVa]

What kind of light bulb are you using? Is it incandescent (old school light bulb), CFL, LED? What is the rated output (60watt? 100watt? etc)

Assume they are also getting some sun (direct or indirect) during the day?

I have a feeling you do need stronger light - depending on where you live and daytime temps, you could start setting them outside for a bit. Would recommend shade for a few days at first, then gradually increase sun exposure.

It also may be worthwhile to hit them with a little fertilizer. You can likely just bottom water with it mixed in.

[acemaker]

Thanks for the information Sean. The bulbs are ones that CaliKim29 Garden & Home DIY recommended. They are Leson 1550 Lumens, daylight.

Unless I am not understanding something, I do not think the light is the problem. The ones growing best are the ones furthest from the light.

I will try both your recommendations for hardening and the liquid fertilizer.

Many thanks again!

[SeanInVa]

I still think the light is a bit underpowered. I have had abysmal results with low powered LEDs. It likely works fine for just getting them started/sprouted though.

Thinking about your setup here, you have three, perhaps four, variables.

1. Potting media and/or presence of nutrients
2. Container size
3. Light access

Unfortunately, they are all grouped together (ie: the plants in larger containers, are using the dollar store media (with or without nutrients) in cups, and are farthest from the light. So you have no idea which are the primary limiting variable(s).

You could try transplanting a couple of the stunted ones into those plastic cups, with the same media (and keep in the same spot under the light) and see if there is a difference.

The container type/size is important here. With the jiffy pellets, the roots will be effectively "air pruned". They might grow out some, but the roots in the cups will likely be much larger, relatively speaking - all other things being equal. They also get the benefit of a little insulation from the cup/media - and thus, are likely to be a little warmer.

The jiffy pellets, in my experience, are great for just getting things to sprout and/or to root cuttings. Once I've seen roots appear/poke through, I get better results by then transplanting them into something larger ("up-potting"). You could transplant into the cups, or whatever you have that allows for more root growth.

[dfollett]

Sean makes some good suggestions. I have never had good results with the peat pellets