The Transworld-published collaboration with cookery writer Judith Wills contains 680 recipes and is billed as "the cookery companion to the world's best-selling gardening books".
Hessayon has written more than 50 Expert guides over the past 53 years, but this is the first collaboration in which the co-author's name came first. He has spoken out against the use of ghost writers: "I detest the concept and it shouldn't be allowed. If you wrote half of it you should share it. They are her recipes and she gets the first name - that was fair."
He added: "I wrote as many words in writing and rewrites as when I'm writing an Expert. I don't usually try and please the publisher or the critics and I don't rewrite, but this time I had to please Judith.
"My job was to map out how I saw it. I begin with the design and writing. That's why it is so different from Titchmarsh's book, et cetera. When you're successful, you are going to get copies.
"I'd be asking what was wrong if there were not lots of books with exactly the same number of pages and of the same size. As long as I'm number one in sales then that's fine. It could be confusing for people coming into garden centres, but I'm not going to get into a tizzy. I've sold 52 million copies."
Hessayon needed a cookery writer armed with recipes for the book, out on 3 March. "I didn't want a celebrity because I'm not into tripping over their ego and them saying: 'Do you know how many books I sold when I was on TV?' It had to be someone who likes the Expert books.
"Transworld drew up a list and I chose Judith. She's not a big name but she has written books and for magazines and it worked perfectly.
"The Veg Expert does extremely well, it has sold six or seven million, and Fruit is more than a million. But I have been concerned for some time that it was only half the story. This completes the veg, herb, fruit and grow your own story."
"There are more Experts to come. The next one is written and is back with me. It will be on gardening and will be out in 2012, but I can't say what it's called. I'm 83 but I've only just begun."