Carrots Love Tomatoes, by Louis Riotte

Reviewed by Richard Robinson

Carrots Love Tomatoes was first published in 1975, coincidentally, the same year I had my first garden. I believe the campus biology department had a copy, but I only glanced at it then, and it left little impression, other than the memorable title, and that marigolds, which I didn’t grow, were good for…um…something.

The book is now 50 years old. I’ve been a casual farmer for much of that time, and a serious one for the past 15 years, without ever planting carrots with tomatoes or marigolds with anything. So when TNF’s editor asked me to review this 50^th anniversary reissue of the book, I was intrigued. What had I been missing?

Sadly, not much. The book is filled with recommendations for companion planting, mostly of the short declarative sentence variety: “Pole beans do well with corn and summer savory. They also have some pronounced dislikes, such as kohlrabi and sunflower. Beets do not grow well with them, but radishes and pole beans seem to derive mutual benefit.” The book is organized by plant and features a good index, making it easy to find recommendations for a plant you might be interested in.

But. 

Almost none of these recommendations come with an explanation for why these relationships might exist, and even fewer have reports of any experiments supporting them. As a result, there is simply no way to determine with what authority any particular pairing is offered. Does the categorical statement, “Radish and hyssop should never be sown near each other,” stem from the author’s experience? From a field trial with multiple replicates in different types of soil? From a neighbor’s complaint? The reader isn’t told, and so at least this reader will not remember this advice, nor heed it if he ever plants hyssop.

There are a small handful of welcome exceptions to this rather dreary pattern. Here is one: “A major enemy of the carrot is the carrot fly, whereas the leek suffers from the onion fly and leek moth. Yet when leek and carrot live together in companionship, the strong and strangely different smell of the partner plant repels the insects so much that they do not even attempt to lay their eggs on the neighbor plant.”

This is great stuff! While the reader will not learn much about recommended spacing, timing, or anything else to turn this persuasive theory into a better crop, it is at least enough for the intrepid farmer to do some trials and see. 

Because here’s the thing. There are undoubtedly benefits from some of the companion suggestions in this book, and probably many cases in which volatiles from one plant confuse or repel the pest of another. Root exudates are another likely mechanism of beneficial (or detrimental) effects.

Good-quality trials of specific companionships may have been done, and it would have been a service to update (or perhaps rewrite) this book to include these and other findings. Are you intrigued? I urge you to consider writing such a book. Gardeners everywhere would be in your debt.