Dame Prue Leith: From Bake Off Queen to gardening judge

But her wealth of growing experience makes her the perfect choice as new judge in this year's B&Q Gardener of the Year competition, alongside returning judges Matt Childs, Humaira Ikram and Steve Guy, with a prize of £10,000 up for grabs.

Around a year-and-a-half ago, Leith, 82, downsized from her Cotswold country manor with the beautiful garden she had created, to a nearby modern house she designed with husband John Playfair on a two-acre plot.

The new garden - featured last year in Channel 4's Prue's Great Garden Plot - is a work in progress, she says. Here, she reflects on how she was a latecomer to gardening and shares the triumphs and disasters of her horticultural life...

How did you become interested in gardening?

"I grew up in South Africa, we had a lovely garden. I spent a lot of time outside because the weather was lovely and we didn't have a television," says Leith.

"Until I was about 40, I didn't have a lot of interest in gardening because I was busy with the children [she had a son and daughter with her late first husband, Rayne Kruger] and with my business. And the children were at the age when they were still kicking balls into the herbaceous border and had all the clobber of sandpits and climbing frame.

"When they went to school, I started to learn the difference between an oak and an ash. I was a latecomer but then I became really obsessed."

You love colour - how do you use that outdoors?

"I like the South African look. We had a lot of oak garden furniture in the old house, which we brought here - and we painted some of it bright red, while the terrace upstairs has Kingfisher blue furniture, like California, and we sunbathe up there.

"The colours of the plants are strong, not muted. If I'm looking for eryngium, I like the most beautiful deep electric blues. We also have tubs of agapanthus on the terrace."

What are you looking for in the competition gardens?

"We've four categories: the classic gardener, where we are expecting maybe hedges and herbaceous borders; the year-round gardener, where we are hoping to see winter interest from someone who's thought about colour and shape the whole year round.

"Then we've got the productive gardener, which appeals to me because it's about feeding people. We're not just expecting a veg garden. It will be interesting to see if people put some vegetables into herbaceous borders or whether they grow herbs in pots and troughs. The other category is the eccentric gardener, which will be a surprise."

What's your garden like?

"My present garden is very new because we've just taken over an old farmyard, which was used for contracting to store enormous machinery so was mostly concrete. We had half an acre of concrete to get rid of before we began.

"We had no mature trees except on the very edges, which used to be the hedgerow. The oldest thing in our new garden is the orchard, which we planted three years ago before we even had planning permission for the house. We just took a chance."

What have you planted in the orchard?

"They are all native British endangered apples, damsons, plums and pears. Last year, we had our first crop of apples and I began to understand why these apple trees had gone out of fashion and were now endangered, because so many of them are tiny and scabby - and we can't spray them because we are trying to go organic.

"The scabby apples are too small to be bothered to peel and a lot of them were sour. However, they made very good apple jelly, which I foisted on my friends in jars."

Do you have a vegetable garden?

"No, because there are only two of us, and I've had my fill of disappointments with vegetable gardens. It's lovely to be eating your own veg, but by and large with a big vegetable garden, you end up with far too many cabbages all ready at the same time. Everything happens at once.

"But we have big agricultural cattle troughs in our courtyard, which are full of plants and veg and I don't have to get on my hands and knees to weed. We are growing runner beans on wigwams and tumbling tomatoes, lots of herbs and lettuces. Last year, we managed to eat it all because we had a little of a lot of things."

Have you had many gardening disasters?

"Plenty. Who hasn't? When I first moved into my old house, it had a very mature garden when we bought it. I didn't like conifers, so I chopped down a huge fir tree and only realised afterwards that it was really strategic to have been put in that place because it acted as a focal point, a column. You often make mistakes because you rush into things."

Did you have a problem growing wildflowers?

"Yes. The thing about wildflowers is that I had thought that, like all flowers, they like really rich soil and a lot of compost. It turns out that if you're going to have soil like that, the weeds and particularly grass just love rich space. The grasses which come up before the wildflowers completely smother the space.

"When John was getting the new orchard ready, having put in masses of compost and leafmould, grit and good topsoil, I thought, wouldn't it be a good idea to have wildflowers growing in between the trees? I bought a load of wildflower seeds and tossed them under the trees and of course the grass came up and smothered them all."

What's your latest project in the garden?

"We've just planted an avenue of trees through a field which goes down to a stream, which involved planting 76 trees - oaks and rowan. Oaks grow very slowly and I'm 82, so I'm not going to see this avenue in all it's glory. I'm hoping no one will dig them up, as they are wonderful for future generations."

What plants do you use for colour?

"We have two beds, which are half grasses and half colour. One side has got a lot of orange and red in it and the other side is blue and purple. The blues include eryngium, purple sedum, blue salvias, with Michaelmas daisies and annual white and pink cosmos to fill the gaps.

"The hot red and yellow border includes grasses with euphorbias, phlomis, Anemone hupehensis, Coreopsis grandiflora, day lilies and fennel."

To enter the B&Q Gardener of the Year competition, visit diy.com/gardener-of-the-year. Entries must be submitted by noon on June 20