Posted: 13/05/2013 at 07:05
Mizzli, separate the tomato plants into different pots. I found a way to magnify the photo so I've had a closer look at them now. They're definitely going to outgrow that greenhouse so they will have to end up outside.
If the instructions told you to plant all the tomato seeds in one pot they're insane.
They're floppy and the stems are weak (and pale-looking from what I can see) for two reasons: the plants' roots competing with each other for space and nutrients in the one pot, and probably a lack of light earlier in their lives.
Here's what I'd do. For however many tom plants there are, buy pots of at least 30cm diameter. Fill them with top quality potting mix. Take the plants out of the current pot and separate the roots. You don't have to do it surgically, just try not to break too many of them.
Then use a pair of scissors to remove all the branches and foliage from the bottom to at least two-thirds of the way up the plants. Nip them off close to the stem. Effectively leave only the canopy at the top.
We don't know the variety but they sure as heck look like an indeterminate to me, meaning they could grow to 5' or more. Get some tomato stakes from your garden centre and, one per pot, push them down into the mix in the new pots until you hit the bottom.
Create deep holes in the mix adjacent to the stakes and bury the plants as deeply as you can. The canopies should be virtually sitting on top of the mix. All of the stem that is buried in the mix will turn into root structure. Pack the mix down very well around the plants and the stakes. And water.
Leave them outside during the day in a place where they will get as much sun as possible. This is the most important thing. Even if it means moving the pots around a bit during the day to maximise the sun exposure.
They're not going to fit back into the greenhouse and you can't take them back inside at night. If the overnight temps stay around 7-10C, get some garden fleece from your garden centre and double-wrap the plants in late-afternoon or early evening as the temp starts to drop. Once the overnight temps get into comfortable double figures you can do away with the fleece.
Don't overwater them. Permanently wet roots will damage a tomato plant. Let the mix dry out to a large extent before watering again. And don't overfertilise them. A feed of commercial tomato fertiliser every 10 days or so will suffice.
Sorry about the long post! Let's know how you go.