Whether they fill your borders, containers or conservatories, tender perennials are as varied as the gardens they colorfully adorn.

Ian Cooke, author of “The Plantfinder’s Guide to Tender Perennials,” says that for him it was love at first sight. “It all began at a Chelsea Flower Show some years ago,” explains the author, who has been a horticulturist for nearly three decades and presently serves as manager of the grounds at Great Britain’s Nottingham University. From “spires of penstemons” to “carpets of verbena ... never before had I seen this range of plants together. Gathered from the corners of the world, all they had in common was their intolerance of frost,” writes Cooke.

It took no sophisticated props for this “sea of colour” to stun onlookers, Cooke adds. For him, such recognition has led to a “deep passion which looks set to become a lifelong devotion.” Today he is an avid collector of tender perennials. He helped found a club of admirers, the Half-Hardy Group through the Hardy Plant Society. And he sells perennials at his nursery, Brockings Exotics.

In the 192-page “Guide to Tender Perennials,” Cooke covers a wide range of subjects relating to the care, feeding and origins of these colorful, varied plants. They can be a stunning addition to any garden, whether on their own, or planted among bulbs, shrubs and annuals, he explains.

The author admits that defining “a tender perennial” was no easy task. For the sake of the book, he calls it a plant “that will grow outside successfully in temperate climates during the summer months, but requires some winter protection,” such as a greenhouse.

He explains that the definition remains vague because there are so many variations in microclimates around the world, and among individual plant’s tolerance to cold.

In addition to explaining just “what is a tender perennial,” Cooke includes chapters on history, habitat and hardiness; using and displaying perennials; propagation and cultivation; and care, such as advice on dealing with pests and diseases. An “A-Z” listing of tender perennials comes complete with recommendations and descriptions of varieties. This section also features several full-color, double-sided pages covered in cutouts of families of tender perennials, such as Osteospermum and Pelargonium.

A section called “Planting Schemes” offers suggestions for using and displaying tender perennials, with detailed diagrams (supplemented with those marvelous photos) for devising beds of “cool colours,” “pastel planting,” or a “Victorian-style formal bed,” for example.

Altogether, this fully illustrated plant directory describes more than 250 species and cultivars, and features information on everything from garden uses to cultural tips, with vibrant color photographs on nearly every page. Near the end, Cooke reminds his readers that “by their very nature, tender perennials should not be planted out until all danger of frost is past,” then follows that up with specific seasonal tips for border preparation, summer and end-of-season care. Arundo donax ‘Variegata,’ Fuchsia cultivars and others are included in a short list of plants that are likely to do well a second season.

Finally, an appendix, “Where to See Tender Perennials,” offers places to see tender-perennial gardening at their finest. Unfortunately, for American audiences, such visits are not easily undertaken as specialty gardens ranging from the age-old Bristol Zoological Gardens to the West Country (and Royal Horticultural Society) garden of Rosemoor are located in England.

Similarly useful only to the British citizen or traveler abroad is a list of “where to buy tender perennials,” in various English locales. Near a breathtaking photograph of the large, pale salmon-colored flowers of Canna, Cooke talks briefly about overseas transport. He doesn’t encourage taking plants out of Europe, and notes that dealing with customs “can be a major problem.”

Besides his present duties as head groundskeeper and entrepreneur, Cooke has held gardening positions at the National Trust and Reading University. He is a frequent contributor to the Royal Horticulture Society’s journal, The Garden. Other books in the series by Timber include “The Pathfinder’s Guide to Ornamental Grasses,” by Roger Grounds.