Dear Ken, John, and all, Ken is generally right, we don't know what makes some plants hardy to cold weather and others tender. At least in many cases. It isn't true in all cases. The physiology of a bulb or any plant changes when it switches from active growth to a resting phase. Bulbs that have to survive cold weather are thought to convert much of their stored starch to sugars (glucose, fructose, sucrose) with the onset of cooler temperatures or shorter days. Starch is insoluble and does not act as an anti-freeze. Soluble sugars like glucose, fructose, sucrose, and perhaps glycerol are effective anti-freeze agents. It makes good sense. Plants that can prepare for winter in an orderly way, can survive the cold. Plants caught unprepared by unseasonable freezes are often killed. Tender plants can not always prepare for cold weather, even when the progression to winter weather is normal, as we all know. The fascinating ones are those that "ought" not be able to survive (so far as we know) but that then do, at least in some microclimates. There are reports describing some of the changes that have been found in some types of bulbs when they prepare for cold weather. See "The Physiology of Flower Bulbs," by August De Hertogh and Marcel Le Nard, Elsevier Science Publishers, Amsterdam (1993), for instance. When plants go back into active growth, the sugars are either used up or reconverted to starch. A perfectly hardy plant like a dormant daylily can be killed when in active growth by a couple days of sub-freezing temperatures. One winter, I had numerous trays of young daylily seedlings growing in the greenhouse in January. We had a power outage, the temperatures went well below freezing inside the greenhouse for several hours, and every single daylily seedling died. Plant hormones that lead a plant to dormancy or to prepare itself to survive freezing temperatures include abscisic acid and ethylene. Plant hormones that waken plants from dormancy to active growth include the gibberellins and auxins. Abscisic acid and gibberellins are natural antagonists in regulating the physiology of plants. Abscisic acid prepares the plant for stress; gibberellins prepare the plant to grow. Regards, Jim Shields in central Indiana, where any sensible plants are far below ground and fast asleep right now. ************************************************* Jim Shields USDA Zone 5 Shields Gardens, Ltd. P.O. Box 92 WWW: http://www.shieldsgardens.com/ Westfield, Indiana 46074, USA Tel. ++1-317-867-3344 or toll-free 1-866-449-3344 in USA