They're currently in the same cell plug flat containers. Some of the plants are a little leggy, so I thought it'd be best to go a deep. Is there any danger in going too deep (as long as you don't cover the leaves)? They'll be going in extra deep solo cups.

I sure wouldn't rush them from a cell plug flat into "extra deep solo cups". That is a very big jump in container size and a major adjustment process for young seedlings that some will not survive. Staged transplanting to containers only slightly larger is the norm so that the plants have a chance to adjust to the increased soil moisture levels.

Depending on the size of the cell or plug packs you are using and the number of plants per cell they can remain in them for at least 2 sets of true leaves usually.

Like Trev I use mostly 288s and they go from those into 6 packs, not full solo cups. Most plants are good in a 6 pack for at least 3 weeks. I'd only plant into 16 oz solo cups once they are 5-6" tall with at least 3 sets of true leaves.

If you could post a photo it would help.

Dave

Thanks for the great advice. I'll get some smaller cups and transplant to them first. These are the cells I'm currently using. On a few of the plants, the first set of true leaves are there. On mostly all of the others, you can see the first set of true leaves starting to form in the center of the cotyledon leaves. I'm sure once I get home from work tonight, mostly all will have grown their first set of true leaves. They're growing like crazy... they went from tiny specs of green on the surface of the soil to 2" almost overnight. Now that I've moved the light to within an inch or two of them, they've grown larger leaves but not so much in height.

Also, is it common for peppers to have gigantic cotyledon leaves? I have a 72 cell bay next to my tomatoes and their cotyledon leaves are 2-3 times the size of the tomato leaves.

Something doesn't sound right with the peppers... tomato and pepper cotyledons are fairly hard to distinguish and of similar size. What varieties are they?

They look like this: http://bunchfamily.ca/watching-little-things-grow/20130404tomatocotyledons/

Chinese 5 Color, Poblano, Peach Habanero, regular and purple Jalapeños, Shishito, and a few others I can't remember at the moment. Yeah, that's how my tomatoes look. It's not quite this extreme, but the peppers look more like this:

https://mountainplover.files.wordpress.com/2013/02/pepper-cotyledons-vs-leaves-lah.jpg

But you say they are 2-3 times the size of the tomatoes?

I only have 2 years experience with a small handful of varieties, but mine have been more or less the same size.

Yeah, just the cotyledons. I've given them lots of heat and attention, so maybe they're just growing quickly? I'll take a photo of both tonight.

You are growing some unusual hot pepper varieties so the folks over on the Peppers forum would likely be more helpful. It is basically an apples vs. oranges comparison.

I have only grown plain Habs, Poblanos, and regular Jalapenos and the cotyledon leaf size and shape of them does change somewhat from variety to variety just as it does with tomatoes. The odds are if you planted peppers then they are normal for that variety.

As for your tomato seedlings, you are using what are commonly called 72s (72 cells per flat) and if single seeded in each cell they can grow for several weeks in that size. If you want to do an interim transplanting before the 16 oz solo cups - great. The 8 oz. foam coffee cups are a good size. Just avoid using clear interim cups as the roots are negative phototropic.

Dave

Thanks again! Yeah, everything, including the peppers look extremely healthy. This is my first time growing from seed and out of 72 tomatoes, 68 germinated and out of 72 peppers, 66 germinated. I expected a lower ratio, so now I have lots of plants to care for.

Yes I never grew unusual hot peppers... I'd be curious if the cotyledons are really that big? Let me know how they turn out!

I cut the tops off of solo cups when I ran out of other containers :)

Might want to get a couple dozen into the smaller white foam cups. (not crazy about buying those things but the white insulation is nice for seedlings)

Especially on your first seed starting season. I plant them deep, half way in the cups and fill soil as they grow. About once a week...then into the solo cups half/or a bit more and fill again as they grow...not the same every year.

Just watch and do as i see their need.

Not sure where you are starting but don't forget some air movement like a fan running on low for most of the day. Air movement helps strengthen the stems and keeps soil diseases and molds from forming.

A bit insane when you get 90+ germination. Hard to let some go. : )

I cull 20-30 % and drop in a bucket by the garden table and they keep growing without any help!...tomatoes are tough to kill.

I've got a couple hundred now and will thin maybe...we always find room. One tray is just from last seasons favorites slathered on paper towel for the seeds, dried and stored...I'm getting 95% germination from those.

Thanks! What kind of soil do you use with the white styrofoam cups? Just a potting mix? Also, do you water from the bottom with a tray and holes in the cups or from the top?

Any growing-on potting mix just as with any container plants. V-shaped holes in the bottom edges just as with solo cups and watering from the bottom is recommended but many do top watering. You just can't use the top of the soil surface as a valid indicator for watering.

You'll find many more discussions about all of this in the How-To FAQs and the discussions over on the Growing from Seed forum here.

Dave