How to get kids into the garden

Now I'm trying to encourage London schoolchildren to garden and to date more than 70 schools have signed up to the competition launched in this paper. But how do we engage them?
The Playground Potting Shed (Guardian Books, £8.99) is a new guide to starting school gardens.

Dominic Murphy has two girls and a couple of years ago he became the gardening teacher at their local Dorset school. He makes simple points which are easy to overlook. First, sort out what you're growing when. There's no point if your veg comes into perfection in the summer holidays, so beware tomatoes, however attractive they look. Stick with beets, beans, peas, potatoes, squashes.

As for kit, school tables make good garden benches and a poly tunnel is brilliant if you have the space. If not, erect a mini greenhouse which consists of a set of shelves against a wall with a 50cm-wide plastic cover (only £25). It will hold enough seedling to get a veg patch going. The River Café's Rose Gray grows salads and herbs in two mini greenhouses on her roof terrace.

Watering is the most popular garden task but kids get excited and seeds are bounced out of soil or drowned in over-watered soil. Invest in a water barrel. You get recycled ones from thetankexchange.com or recycled oak ones at www.plant stuff.com (£20-plus for a 100-litre butt).

Tiny seeds fly all over the place so don't give kids the whole packet. To cut costs and up the fun, ask students to bring containers from home — like leaky mop buckets, old tins, suitcases or even their mother's hats.

But kids need their vegetables to grow. Last week I saw the ultimate in idiot-proof gardening: ready-seeded salad rolls which will ensure your children get a reliable crop. Packed in a long carton which resembles a box of clingfilm, the rolls consist of a layer of biodegradable clear plastic, attached to biodegradable substrate.

Between the two are rows of salad seeds. The clear plastic has holes punched in to let in water (not much, as it stays there, making the salad crops light on water use). Spaced along each row of seeds are strong lettuces such as cos, which push the plastic upwards creating a mini-polytunnel effect around the other seeds. The blue of the substrate, which feeds the seeds, suppresses ultra-violet and prevents it reaching the weeds underneath. After four weeks, remove the plastic. The leaves are clean, dirt-free and chemical-free.

Seeds rolls measure four foot by 1.6 and you cut the fabric to fit whatever container you want — from a pot to a raised bed. The rolls are available from www.themasterherbalist.com and from Waitrose from May onwards. There are three varieties of lettuce: English summer salad, oriental mix and Mediterranean mix, £5 to £7 depending on the retailer.