Some questions about my vegetables...

[snickersnack]

...I am making this up as I go along, and planting things without a huge amount of research. But it occurred to me a bit of knowledge might help a lot. So:

• carrots: how do I know when they are ready to eat? They've come through but I didn't plant that many so don't want to waste them by pulling one up only to find there's no carrot on the bottom

• potatoes: as above, really. I'm chucking more compost on every time I see leaves poking through, but what happens when I reach the top of the pot? How do I know when there are potatoes there?

• spinach: I planted 2 plants before Christmas that we bought at the farmers' market. They are thriving - can I just keep cutting leaves off them, and will they keep growing.

• tomatoes: have been given some plants by a friend. Have repotted them. Now what?

If it all comes together, we may be able to avoid veg shopping altogether for a couple of weeks, which would be great. But am worried that I haven't really gone about this with any great thought.

I have found it trial and error really keep them well watered and give tomatoes extra plant food as it makes a real difference. They will grow nicely over the next few weks and should be ready for eating july, august.
Carrots- when the leaves are about 20 cms or more and really leafy they should be big underneath just pull one and see what its like when it gets to this point.
Spinach should be good for cut and come again as you described.
DH is really the gardener so see what other more expert people say.
Have you ied growing corgettes and butternut pumpkin they are really easy and good to eat. Also spring onion.

I'm doing my first serious vegetable growing year too (although have done tomatoes and lettuce in previous years)

I can't answer your carrot question but I think you can tell that potatoes are ready when they flower. You just add compost to the top of the pot then stop and wait for them to grow tall and flower.

Tomatoes will produce little yellow flowers which then drop off and tomatoes grow there. You can start feeding them with something like tomorite at that stage i think (I'm a bit crap at remembering that bit and have varying results!)

snickersnack, just to reiterate what previous poster said - yes, stop putting compost on the spuds when you get near the top of the pots - then let them grow as much as they want. They will flower. As zisforzebra says, this means they are making little potatoes. There's a good RHS online info sheet about this:
www.rhs.org.uk/advice/profiles0506/potatoespots.asp

And tomatoes:
www.rhs.org.uk/growyourown/tomatoes.asp

Actually there's lots of excellent advice on that site so maybe just go there and have a browse!

Tomatoes - you will need to pinch out the tops of the plant when they have set around 5 trusses. This means when you have 5 separate branches with little yellow flowers on them, you snap off the top growing part of the whole plant above these branches. Otherwise your tomatoes will be small.
And all the time your plants are growing, you have to pinch the 'hair out of their armpits'...imagine that these armpits are upside down and occur where the branches come out of the main stem of the plant. Have a look, you'll see what I mean! You'll have to do this on a weekly basis.

The side shoots on the tomatoes only need to be pinched out if they're vine types (most but by no means all are). If they're bush types then you can let them branch out and make a small bush.

Spinach: Just keep harvesting leaves - the more you pick the more they grow (so long as you don't completely strip the plant) & it helps prevent them from bolting too.

Potatoes: either wait until they flower, or if you want bigger spuds wait until the leaves start to die back. They need lots of water to swell the tubers in the final stages. You can have a 'furtle' around in the soil to find the spuds & see what size they are if you're not sure if they're ready - but with mine I found they were all right at the bottom so not easy to do. Some people suggest putting the pot on its side & gently pulling the whole rootball out, looking at the potatoes and putting it all back again if you want them to grow some more (maybe removing a few larger ones).

With the carrots, you can gently push the soil away from the plant at the base of the leafy bit and if you can see a nice large carrot top then you can pull it. But if not put the soil back again - you don't want to leave the top of the carrot showing or it will turn green. I find some get large quicker than others, so you need to be selective about which you pull first.

Thanks very much - will have a look at the RHS site. And will go and harvest the spinach now.