Tonight after work, I'm hurrying up the road with a massive bag of chopped-up plastic bottles. Why? Well, at the weekend, we enthusiastically planted out our tiny tomato seedlings into the allotment. They seemed quite big (until we put them into the ground), and we need the space on the shelves in front of the window for our next seedlings. So now, of course, the law of sod being what it is, after the 21 degress of the weekend, temperatures are set to plummet to just above freezing, and frost (that's the F word in our house) is a real possibility.

Our weedy* little seedlings are so tiny that I fear for their survival - even tucked inside plastic bottle mini-cloches. And I need these seedlings to flourish: the Royal Horticultural Society has challenged me to grow them, and show the resulting produce at an autumn show!

You can join in too. As part of its Grow Your Own campaign, the RHS is challenging all gardeners to grow four types of veg: Tomato 'Alicante' (my tiny toms), Beetroot 'Boltardy', Chilli 'Chenzo' and Pumpkin 'Hundredweight'. Over 10,000 people have already joined in, and you'll find loads of advice, growing tips, recipes and more on the RHS website.

Read more on growing tomatoes from seed

*weedy, paradoxically, is not an adjective that can be applied to vigorous, thrusting nettles, couch grass, chickweed, dandelions...