Book excerpt: Which vegetables should you plant in your garden? The answer really comes down to maths. It doesn't matter where you garden - in an allotment, in containers, in raised beds or straw bales, or in a Square Metre Garden - deciding which vegetables to plant is perhaps the biggest factor in whether or not your garden succeeds. While success means many things to many gardeners, there's no avoiding the issue of cost versus payback. Does it make sense to spend GBP3 and use up almost a metre of garden space to grow one cabbage when you can buy a beautiful one at the farmers market for GBP1? Author Mel Bartholomew has been a gardener and engineer for many years and he has learned this: Even in the garden, maths is your friend. In Square Metre Gardening: High-Value Vegetables, Bartholomew describes how to apply basic maths (and a little economics) to any vegetable garden and get some objective answers about which vegetables give you the best return on investment. In this latest book in the Square Metre Gardening family, Bartholomew ranks the vegetables that are most common for home-growing and concludes which ones give you the most value for your investment. He looks at many factors and makes hundreds of calculations, and the answers all become clear. And in the process he finds some surprises (tomato lovers will be pleased, but if you grow potatoes, you're in for a shock). In the end, though, there are so many things to think about when you're choosing plants - whether or not they are edible - but the truth is, you'd be a bit foolish not to think about ROI. With Bartholomew's new book, you can do it without ever taking out a calculator. You'll find the information incredibly valuable when it's time to plan your own vegetable garden. Plus, you'll find plenty of great tips along the way for maximizing the value you get from each and every crop you plant.