What would it be like to have a blank canvas for a garden, just a patch of land with nothing in it - no design, beds or borders? Well, to presenter Monty Don, it was pure bliss.

Nearly 20 years ago Monty and his wife Sarah were among Britain's leading designers of fashion jewellery. But when the recession hit they lost everything, including their business and their homes, just managing to scrape together enough money to buy a near ruin of a house in the Herefordshire countryside.

There, Monty, who suffered from crippling bouts of depression, threw himself into creating a garden in the bare two-acre field behind the house, before TV work came his way and he was able to claw himself out of poverty.

They still live in the same house and, after much hard work, have a beautiful garden, which is detailed in their new book, The Jewel Garden.

"In many ways, a blank canvas is the easiest place to start from," says Monty. "It means that anything is possible.

"The disadvantage is that what you see in your head is a finished garden. For the first three years everyone's got to trust that you know what you are doing because you won't be able to see it. After three years, some people will say, 'Ah, that's what you mean,' and, after seven or eight years, everybody will see exactly what you saw in the beginning."

Monty takes a notebook everywhere to write down garden ideas, sketch and visualise.

When they were in their 20s, he and Sarah would take a week out every year to visit public gardens, where they gained much inspiration. So, what advice can he give people who have a blank canvas at the back of their house?

"Find the sun first of all," he says.

"Don't do anything until you know exactly where the sun falls in your garden from sunrise to sunset. That will take a full 12 months. People will be surprised at the difference between where the sun falls in winter and summer.

"Make a place that is private in the garden when you most want the sunshine. If your idea of heaven is to have your morning cup of tea, before going to work, sitting in the garden, that should become the focus. It must be where you don't feel overlooked.

"Work out what you want from the garden, rather than what the garden wants from you. If you've got small children you are going to need somewhere near the back door where they can play. If you don't really want to cut grass, don't have a lawn.

"Work out your structure. It can be simple, it doesn't have to be geometrical, and plant any hedges or fences or walls or trees, then you can fill in with plants later. Imagine the garden on a mid-winter's day. Ask yourself what it will look like then. It must look reasonable. A really good garden is pleasing even then, even if it's just the stone or brick or wood. It's like a good face - bone structure."

Gardeners can never spend too much time getting their soil right, he stresses.

"Whatever work you put into your soil will be repaid," he says. "You can't have a good garden with awful soil. It might mean digging, adding lots of compost or manure, or making raised beds for vegetables."

Monty's final piece of advice for those just starting out on their blank canvas is: don't fight nature.

"If you live by the seaside then you can grow plants that like salt but if you live on top of a mountain, don't grow plants that need a sheltered position. It's pointless because nature always wins."

n The Jewel Garden, by Monty and Sarah Don, is published by Hodder & Stoughton, price £20.