Tomato seedlings

[Mrhwbin]

First time grower from seed. Are these what you would call leggy? They are on a sunny windowsill.

So what size pot do I go up to next and how deep should I plant, I.e. how much stem shall I leave showing?

Thanks in advance.

Usually when potting on you would plant to the same depth as previously, but because tomatoes will produce roots from further up the stem you can plant them a bit deeper to stop leggy seedlings waggling about. They are related to the potato so that makes sense really.

Don't make a huge leap in pot size, just a size or two up. There are sound horticultural reasons why over-potting does more harm than good, but I can't remember what they are offhand.

@Mrhwbin That's a good healthy seedling. Do as yamadori says

@yamadori is it not to do with inactive (ie no roots in it) soil becoming stale and unaerated? I'm now wondering why it doesn't happen to a bag of compost, but I suppose it's because you are watering the plant, the plant is extracting water from around its roots, but the soil the roots can't get to isn't drying out before you add more water to the plant. Therefore it loses oxygen, and it's not going to be good for the huge array of tiny invertebrates and micro-organisms on which soil health depends.

I suppose then that would lead to the rule (that works in practice) of not potting into a pot too big for the plant to fill within a few weeks. You can pot a vigorous plant into a larger pot than a slow growing plant.

that's a good looking seedling.
next step should be to plant it out. either into a veg patch or a pot. tomato pots (5liter) are a good size.
plant as deep as you can, up to the first leaves.
don't forget to add support, they can get really tall!

it's still a bit cold at night though, tomatoes shouldn't get colder than 5 degrees.

@MereDintofPandiculation Yes - if the plant is in a pot which is much too big for it, all the soil at the bottom gets stale, waterlogged and airless which discourages roots from growing in it. Something like that anyway. Those that do have a tendency to rot in the winter. Either that, or a handful of roots rush straight to the bottom of the pot and go round in circles and then upwards like a wall of death, rather than filling the compost throughout the pot with numerous shorter roots, which is what you want the plant to do.