Last weekend I was struggling to find space on our dining room floor for my tomatoes, chillies and other tender veg; days later I could not get them into the balmy air quick enough. Can it really only have been a little over a week ago that it was snowing on my plot? On Friday I spent most of the time sitting in the shade of my quince tree, trying to keep cool potting on nearly 30 tomato plants while the bees buzzed around the blossom over my head.

The tomatoes that I’d moved from home last week had had five days of getting used to being outside – at first with the mini-greenhouses closed, then by the middle of the week, as the temperatures rose, with the doors rolled up to allow air to circulate.

Before transplanting my tomatoes, I took an audit of all the plants – including the ones that have been on the plot in mini-greenhouses for about six weeks. An audit sounds a bit obsessive – but tomatoes bring out the obsessive in me. I had sown so many different varieties (around 30), and in different batches – to make up for earlier losses due to cold – that I wanted to work out which plants I will grow on my plot, and which I will sell at our allotment stall at the local fete in Nunhead, south London, later this month.

For some varieties, I had a glut: all six seeds of ‘Yellow Pear’, for example, had grown into strong, robust and healthy plants. But for others, the results were disappointing: I sowed four ‘Rosella’ seeds and only two germinated, and by Friday those two were sickly, small plants. This could be related to the age of the seed (the Yellow Pears were from a fresh packet) but also to where they had been when the cold snap hit the country (the Rosellas, along with some other varieties, were in the mini-greenhouse when it snowed – although other varieties had survived).

Over the past decade and a bit I have grown tomatoes three different ways: in pots (no smaller than 10 inches/25cm), grow-bags and in open ground, and always outdoors (I don’t have a proper greenhouse). In my experience, the grow-bags produce the worst results – smaller plants and lower yields. Last year the tomatoes in open ground did OK during early summer and produced dozens of fruit, but at the back end, after a wet August, they were hit by blight. Growing in pots does not make tomatoes blight-resistant, but you can more tightly control the conditions of a pot-grown plant than those in open ground – such as allowing for more air circulation and keeping the soil drier, which can lessen the risk of blight.

It is more expensive, but I add a fresh mix of ordinary compost and rotted manure to each 10″ pot before planting the tomato, which gives the plants the boost they need to start flowering and setting fruit. Space is a premium, as ever, so I am placing the potted tomatoes along the network of paths. One 10″ plastic pot broke apart as I was counting them, so in the end I had 29.

For my audit, I counted how many plants I had of each variety and what condition they were in – a cross for dead or dying, a 1/2 for weak and probably not worth saving, and a tick for healthy plants. Of the 71 plants, 10 had died, 18 were of poor quality, while 43 were healthy. I was disappointed to find that ‘Bloody Butcher’, the variety I was most looking forward to growing – an heirloom variety, it has gothic blood-red innards – had succumbed to the cold. Although this goes against everything that gardeners know, and I have no hope of it working out because May is too late to sow tomato seeds (particularly in the south), I nevertheless sowed some more ‘Bloody Butcher’ because I am, if you like, bloody-minded.

I picked 29 of the healthy plants for my pots – one of each variety that had survived, plus two or three of my favourites (‘Yellow Pear’, which is delicious as well as pretty, gets three of the spots). The remaining 14 will stay in their little 4″ pots until they can be sold at the fete.

I am taking part in a trial of vegetable seeds for Big Allotment Challenge winner Rob Smith, which I first blogged about back in February. Of his seeds, I am growing three tomatoes, two chillies, a courgette, French bean and a pumpkin. It is a blind trial so I don’t know the varieties. The tomatoes have produced mixed results. This may be because they were in the first batch sown in February and possibly struggled as winter went on longer than normal.

I sowed three seeds of Tomato ‘A’ in February. One of them germinated. This tiny seedling grew quite well until I moved my first batch of sowings to the playhouse. In March, temperatures went below freezing and even though they were undercover, quite a few plants died, including Tomato ‘A’. I sowed two more seeds, and only one germinated. Again, this seedling battled on but did not survive the latest cold snap at the end of April.

Rob’s Tomato ‘B’ fared only slightly better. Two seedlings nearly made it to the end of last week, when I took my audit. One was clearly defeated by cold – brown and shrivelled. The second I marked as 1/2 – not good enough to go straight in a bigger pot, but I am not giving  up on it – I put it in a slightly larger pot and if I give it some love, maybe it will pull through.

I have happier news about Tomato ‘C’. I have one healthy plant that has gone into a bigger pot. I cannot tell what variety it is as the leaves are standard tomato ones, but it will be exciting finding out what the fruit looks like.

A small diversion to mention the chillies I am trying out as part of Rob’s trial. Chilli ‘A’ and Chilli ‘B’ are doing fine and should make it through to full growth. Chilli ‘A’ is turning into an unusual-looking plant – not the traditional smooth sharply pointed leaf normally seen in chillies but a rounder edge, deeper veins and, crucially, fine hairs on the surface.

The fine hairs suggest it is part of the Capsicum pubescens species – thanks to Beryl of mudandgluts.com and Mark Willis from marksvegplot.blogspot.com for helping with identification. Mark suggested it might be ‘Rocoto’, one of the C. pubescens chillies. As with the tomatoes, the variety will show itself when it produces fruit.

Returning to the tomatoes, then: once the first yellow flowers form, they should be fed with a liquid tomato feed every 10 days – I would increase this to once a week once the fruit start to emerge. Most of the varieties are cordons, meaning they will need staking, particularly in pots. Cordon varieties (but not bush types) need side shoots removing so they can concentrate on growing fruit. After four trusses of flowers/fruiting buds have formed, pinch out the tip – this will make the plant more productive.

Tomatoes need plenty of water – especially in this hot weather. In pots, they need saucers to stop the water (and rain) draining away. Grow-bags also dry out quickly. The downside to pot-grown tomatoes is they need daily watering in hot weather, so if you are going on holiday you need to have a friendly neighbour to help out with the watering can (and return the favour when he or she goes away), or make reservoirs out of upturned plastic water bottles.

I use a 500ml plastic water bottle for each pot (start collecting now for summer). Cut the bottom off the bottle. Make tiny pin prick holes in the neck or sloping shoulders of the bottle. Turn the bottle upside down, with the lid still screwed on, and plunge the lid and neck into the pot soil until the holes are below soil level. Fill the upturned bottle with water. This will provide a slow release of hydration for a week or more. Don’t worry about over-watering – the holes will be small enough to prevent that, and the saturated soil will help keep the excess water in the bottle.