why pot up?

[jdlondon]

I mean, when you sow directly into the ground, surely the plants don't suffer from having all that soil and space - so why should seeds started in containers not start in its final big container?

I have space issues, in that I don't have much, so I'm trying to figure out must-haves and optionals. And you might think pots stacked together don't make much of a difference, but I'm tripping over things already and I have nightmares of tipping off the balcony so frankly, every little bit helps.

[Aberdeenplotter]

I'll give you a couple of specific examples. I grow leeks and onions for exhibition. Onions from seed and leeks from pips. If started in large pots, they sit and do nothing. However, if started in smaller pots and left until the roots are starting to fill the pots, they thrive and when potted on into slightly larger pots, really thrive again when they start to fill the larger pots with roots. Also, many plants can be planted out from small pots so it would be very wasteful in terms of compost and in terms of space to use larger pots from the start.

[SarrissUK]

It's also a way of protecting little, vulnerable seedlings from the big bad slugs and other pests. Having said that, I sow an awful lot direct into where they are to grow on the allotment for exactly the same reason as you - space! Despite having a 25 foot long kitchen, I have limited space compared to how much I want to grow up on the allotment. I tend to start veg that need warmth earlier than my outdoors can provide such as squash, cucumber, gherkins, chillies, peppers, sweetcorn... The rest have to rough it outside when I run out of space inside

[Ananke]

I've often wondered the same thing, the seeds I sow directly into the soil do really well so why would it be any different in a large pot. I dunno.

[zazen999]

We don't wash the nutrients away down the drain when planted straight in the soil.

I go with the main theory of 'grow healthy plants' and then pick my best ones to go into valuable compost. My not so best ones go in nooks and crannies and usually [but not always] produce smaller crops than the best ones.

But if you don't have space, then go for it! It's your balcony and you can do it whatever way you want.

[Potstubsdustbins]

We are trying to get the best out of every seed, in nature that doesn't need to happen. If you think of a tomato, the vine will drop all its tomato's into a given area, literally thousands of seeds. It doesn't need many of those seeds to germinate for the line to continue.

Colin

[Two_Sheds]

I mean, when you sow directly into the ground, surely the plants don't suffer from having all that soil and space - so why should seeds started in containers not start in its final big container?

In a container the unused compost can go sour, esp. if overwatered. In the ground, you have natural drainage which doesn't cause that (unless you have boggy acidic soil of course)

[jdlondon]

So it's basically of concentrating goodness in the soil for your chosen plant alone, and cost-effectiveness, reducing waste of soil unused by the little plant while it grows but which will lose its nutrients since it's getting watered just the same regardless of whether it's being used. Ok.

I think I'll have the small ones for germination and then the next step up, 3 inchers I think, and then wait until they're strong and overflowing that before transplanting to the beds.

[Collierygarden]

I realise this is an old thread now, but I was curious myself, so did a bit of research!

Apparently plants send out their roots almost horizontally to the edges of the space they're growing in first, however big the space may be. If they hit a boundary after a while (edge of a pot), this means that about three-quarters of the plant's root system is crowded on the outside edge of the container - the inside bit of the pot is hardly used.

By using a smaller pot first, then a slightly larger one, then larger etc, it forces the plant to arrange their roots almost into rings, therefore using the inside space in the pot and getting the most out of the nutrients available (and hence a better plant).

This obviously isn't a problem by planting straight into the outside ground, as there isn't usually a boundary which will cause the roots to stop and crowd round each other. If you used a massive pot, where the roots would never reach the pot edge, and aren't bothered about all the 'wasted' space, then this would be fine too.

They've done electronic imaging of plant roots on this article, which goes into more detail:

BBC Nature - 'Stunted' pot plants cannot reach full potential

[Jungle Jane]

I remember reading something about double planting things like cauliflower to disturb the taproot,to improve the root system. Same as when you pot on,you break the run of the tap root,it is interesting.
Root Development of Vegetable Crops: Chapter XXVI
"Transplanting or potting of seedlings tends to modify the natural taproot system into a more or less fibrous one, due to the injury to the taproot. The change in the root system is really very profound"