Gardening: Made it! my own little Sissinghurst

I feel as though one of our children has won a scholarship, or a first novel has been accepted, or a painting selected by the Royal Academy. Next year our little London garden will be in the National Garden Scheme's Yellow Book, alongside such names as Sissinghurst, Great Dixter and Sandringham.

For 20 years we have pored over the National Gardens Scheme guide, using it to plan outings, never going on holidays in this country without it. For the past couple of years we have wondered whether we dared to suggest that our own garden be included. Now we have made it. And to add to the satisfaction, we didn't even have to apply: a friend persuaded us to enter a local gardening competition, our garden came second, and we were asked to consider opening it to the public.

The organisers, all, of course garden-mad and all volunteers, are always on the lookout for new gardens. Yet a third of those who offer their gardens receive a polite "thanks, but no thanks".

London organiser Penny Snell explained that there are three criteria when choosing a garden for inclusion. It must have a design, it must have "horticultural interest" and it must be well maintained.

Visitors are demanding, she said, and are quick to complain if they travel across London to see a garden and decide it is not up to scratch.

In general, to be included in the book a garden should hold the visitor's interest for 40 minutes, but this rule has to be relaxed in London, where the list includes fascinating but tiny gardens. Mrs Snell tries to group several in one area, arranging for them to open on the same day.

The garden-opening scene in London is slightly different from that of the country. The population is more mobile, so gardens are often lost to the scheme when owners move. With smaller gardens there is less scope for rearrangement; visitors are unlikely to return to see the same patio, however original. In the country, areas in big gardens are often redesigned or replanted. Visitors are happy to return each year to monitor progress. Our garden has progressed steadily until now, but is unlikely to change radically in future.

The date for opening is fixed for next June, and we are already worrying about how to describe our garden in the book. Does "plant person" (a phrase well understood by some, but baffling to others) sound too Islington? If we mention the clematis, will they be in flower? Does "country-style" make it sound like a sausage? Should we offer tea (a cup of, with a biscuit), or teas, which means homemade cakes? The organisers are firm on this point. Just as visitors know Geranium endressii from geranium "Claridge Druce", they will know a homemade cake from an M & S one.

I enjoy gardens with plants for sale, and I like potting up bits from my own garden, but will they be good enough to buy? And how to price them so that they sell, but not in the first 10 minutes?

Worst of all, will someone write to Mrs Snell complaining about the floppy old roses? I shall have to stand near them, saying firmly that they are meant to be like that.

Next year's National Garden Scheme guide will be on sale in early spring at most good bookshops, price pounds 3.50, but this year's has details of early openings in 1997 for snowdrops. The scheme raised pounds 1.3m last year for charities including the Cancer Relief Macmillan Fund, nurses' and gardeners' charities and the garden fund of the National Trust.